The Store_field(result, 16, arch_config) sits inside an #ifdef x86, meaning
that on other architectures the pointer is not filled in. Ocaml code then
falls over a NULL(ish) pointer (really the Val_unit used to initialise
'result') when the layout in the heap doesn't match the type system.
Rearrange alloc_domaininfo() to avoid this. Similarly to
physinfo_arch_caps(), raise an exception if the architecture code hasn't
filled in an appropriate tag. Move the setup of arch_domainconfig to be
common logic.
In order to simplify the addition of other architectures, remove the
arch_config variable (reusing tmp as it's touched exactly once), and rename
x86_arch_config to be arch_config so each architecture can fill in a suitable
one without needing more local variables.
Fixes: 9d683b5e37 ("tools/ocaml: Expose arch_config in domaininfo")
Fixes: 81838c9067 ("ocaml: fix arm build")
Reported-by: Julian Vetter <julian.vetter@vates.tech>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Teddy Astie <teddy.astie@vates.tech>
Release-Acked-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
(cherry picked from commit 365d2a5be3)
pv_map_ldt_shadow_page() takes the whole guest PTE, adds _PAGE_RW to it, then
installs it into Xen's pagetables. It has had this behaviour ever since LDT
support was added in 2003.
However, it allows the guest to control the software available bits and
cacheability. This happens to be benign right now, but is bad form.
Use only the guest frame, and construct the mapping as regular RW frame, and
notably includes NX. This is how the GDT logic already works.
Fixes: 005c272397 ("Finished virtualisation of x86 LDT")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 1cc1f4d7a0
master date: 2026-07-14 17:31:08 +0100
The APM description of the AltMovCR8 feature bit is:
"LOCK MOV CR0 means MOV CR8"
Adjust the decode logic to behave like this.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Teddy Astie <teddy.astie@vates.tech>
master commit: 7d48ef45b6
master date: 2026-07-10 19:35:49 +0100
Returning from an NMI which hits guest context needs special casing in FRED
mode just like it does in IDT mode.
Break nmi_exit_to_guest() out of handle_ist_exception(), and use it in
entry_FRED_R3() also.
Expand the comment a little, and invert the conditional jump to
compat_restore_all_guest() to avoid needing an #else clause for CONFIG_PV32.
Fixes: 87cfcbe9f0 ("x86/pv: Guest exception handling in FRED mode")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 76fc776392
master date: 2026-06-25 11:08:02 +0100
Prior to commit 9c20d3c591 ("x86/IDT: Make idt_tables[] be per_cpu(idt)"),
the global idt_tables[] was always safe to use for CPUs in any state.
However, not-yet-onlined CPUs (e.g. MADT with more entries than exist in
practice) or offlined CPUs (e.g. xen-hptool) have their per-cpu pointer
poisoned to detect incorrect uses. machine_kexec() trips over the posion when
clobbering #MC entry paths. Update the comment to discuss parked CPUs, and to
remove discussion which isn't particularly relevant to the actions at hand.
This fixes a fatal #GP (non-canonical memory reference) when trying to enter
the crash kernel.
Fixes: 9c20d3c591 ("x86/IDT: Make idt_tables[] be per_cpu(idt)")
Reported-by: Lin Liu <Lin.Liu01@citrix.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 2c9829a261
master date: 2026-06-23 19:15:51 +0100
With FRED just as with IDT, it's unsafe to run the exception handlers after
switching stack.
To remove this unsafe window, %cr4 needs clearing earlier. In turn, we may
need to switch to PCID 0 earlier too in order to be able to clear CR4.PCIDE.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 4665d17967
master date: 2026-06-23 19:15:51 +0100
After switching stack, it is not safe to run any exception handlers, because
attempts to access the cpu_info block are out-of-bounds and will generate wild
accesses.
Invalidating the IDT in the common path means there's no need to do so again
in the 32bit path, so drop compat_mode_idt entirely.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: c3974cbf20
master date: 2026-06-23 19:15:51 +0100
When FRED is active, it is not possible to hook NMIs like this.
NMI hooking in the crash path has undergone several revisions since its
introduction. Notably since commit e7f147bf4a ("x86/crash: Drop manual
hooking of exception_table[]") we use the regular nmi_callback()
infrastructure.
Instead of asserting that we don't enter do_nmi_crash() on the crashing CPU,
tolerate it and return early. It's a marginally longer codepath but behaves
the same and is compatible with FRED.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: ad9c7d86c9
master date: 2026-06-23 19:15:51 +0100
There is a 3rd path which should have gained an is_zen6_uarch() check to
exclude Zen6 from entrysign mitigations.
Fixes: bd15fdedaf ("x86/ucode: Exclude Zen6 from entrysign mitigations")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Teddy Astie <teddy.astie@vates.tech>
Acked-by: Jan Beulich <jbeulich@suse.com>
master commit: 6ba5e9c7b8
master date: 2026-06-16 18:33:39 +0100
In order to avoid serialising the testing on both boards, the runner
configuration is being adjusted.
Have the .xilinx-arm64 and .xilinx-x86_64 templates choose the board directly
using a more specific tag.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Victor Lira <victorm.lira@amd.com>
(cherry picked from commit efcb4c5e2f)
In FRED mode, the SYSCALL instruction does not modify %rcx/%r11. All current
software using SYSCALL expects the pre-FRED behaviour and spills %rcx/%r11
around the invocation, which is why FRED not doing this goes largely
unnoticed.
However, consider the following migration scenario:
* VM suspends. Hypercall, so SYSCALL, %rcx/%r11 left unmodified
* VM moves to a non-FRED system
* Xen resumes the VM with a real SYSRET instruction
Instead of resuming at the instruction following the SYSCALL instruction, the
VM is resumed at whatever dead value was in %rcx.
In FRED mode, manually adjust %rcx/%r11 when SYSCALL is used and when SYSRET
would have been used.
Regarding the choice of instructions in eretu_exit_to_guest(), a branch would
be a context dependent 50/50 split (i.e. increased chance of mispredict), and
only saves one instruction. The CMOVs read the same cacheline that ERETU is
about to process, so are as close to free as we can reasonably get.
Fixes: 76193ef47d ("x86/pv: System call handling in FRED mode")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: c5a4b9125b
master date: 2026-05-28 16:19:16 +0100
libxl_nocpuid.c needs the same treatment as libxl_cpuid.c
Fixes: f6c6f2679d ("libxl: Convert libxl__object_to_json() to json-c")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Anthony PERARD <anthony.perard@vates.tech>
(cherry picked from commit ca7906501e)
Under SVM, there are two copies of guest CR2. One is v->arch.hvm.guest_cr[2]
and one is in the VMCB.
Xen doesn't intercept CR2 accesses, so this mostly goes unnoticed; hardware
loads and saves the guest CR2 in the VMCB across VMRUN/VMExit.
For HAP guests (where #PF is not intercepted, and therefore we don't typically
inject #PF either), this causes the guest CR2 value to be lost on migrate. As
migration is cooperative and not done from the #PF handler, this also goes
unnoticed by guests.
It also means that an emulated MOV-from-CR2 reads a stale value.
Reported-by: Stefano Stabellini <sstabellini@kernel.org>
Fixes: d1bd157fbc ("Big merge the HVM full-virtualisation abstractions.")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Tested-by: Stefano Stabellini <sstabellini@kernel.org>
Reviewed-by: Teddy Astie <teddy.astie@vates.tech>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 3e6bca616b
master date: 2026-05-05 11:45:00 +0100
Gitlab CI reported a crash on boot on Alder Lake hardware. The bug is years
old, making it an incredibly rare occurance:
(XEN) *** DOUBLE FAULT ***
(XEN) ----[ Xen-4.22-unstable x86_64 debug=y ubsan=y Not tainted ]----
(XEN) CPU: 0
(XEN) RIP: e008:[<ffff82d04077bbc4>] arch/x86/setup.c#reinit_bsp_stack+0xfa/0x160
(XEN) RFLAGS: 0000000000010202 CONTEXT: hypervisor
(XEN) rax: 0000000000000007 rbx: ffff83049a4b0000 rcx: 00000000000006a2
(XEN) rdx: 0000000000000000 rsi: 0000000000000000 rdi: 0000000000000000
(XEN) rbp: ffff83049a4b7f00 rsp: ffff83049a4b7ef8 r8: ffff830497e47000
(XEN) r9: 00000000ffffffff r10: 00000000900c2121 r11: 000000009a392956
(XEN) r12: ffff830497e47000 r13: ffff830497e49f40 r14: 0000000000000000
(XEN) r15: ffff82d0407dad10 cr0: 0000000080050033 cr4: 0000000000f526e0
(XEN) cr3: 0000000043c16000 cr2: fffffffffffffffc
(XEN) fsb: 0000000000000000 gsb: 0000000000000000 gss: 0000000000000000
(XEN) ds: 0000 es: 0000 fs: 0000 gs: 0000 ss: 0000 cs: e008
(XEN) Xen code around <ffff82d04077bbc4> (arch/x86/setup.c#reinit_bsp_stack+0xfa/0x160):
(XEN) 00 b9 a2 06 00 00 0f 30 <80> 3d 71 26 f1 ff 00 74 3e 48 8d 93 f8 5f 00 00
(XEN) Valid stack range: ffff83049a4b6000-ffff83049a4b8000, sp=ffff83049a4b7ef8, tss.rsp0=ffff83049a4b7fb0
(XEN) No stack overflow detected. Skipping stack trace.
(XEN)
(XEN) ****************************************
(XEN) Panic on CPU 0:
(XEN) DOUBLE FAULT -- system shutdown
(XEN) ****************************************
This is on the instruction boundary after enabling CET (writing MSR_S_CET) and
prior to establishing SSP. Despite identifying this as a critical window
where any fault was deadly (the CPU tries to push a shadow stack frame at 0,
hence the CR2 value wrapping around to the top of the address space), I
clearly forgot that this meant interrupts too, which are enabled.
Disable interrupts during the critical period.
Fixes: b60ab42db2 ("x86/shstk: Activate Supervisor Shadow Stacks")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Teddy Astie <teddy.astie@vates.tech>
master commit: acfd2631b9
master date: 2026-05-05 11:45:00 +0100
Right now, xstate_alloc_save_area() leaves both XSTATE_BV and FTW clear. This
causes a difference in behaviour between FXRSTOR and XRSTOR.
Switch to using using XSTATE's idea of initial configuration which will behave
the same even on pre-XSAVE hardware. Expand the comment to explain why.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 639de2aafa
master date: 2026-03-30 15:48:13 +0100
Hans reports that Xen no longer builds on Debian unstable/sid:
Assembler messages:
{standard input}:474: Error: unknown or missing system register name at operand 1 -- `msr TEECR32_EL1,x0'
{standard input}:480: Error: unknown or missing system register name at operand 1 -- `msr TEEHBR32_EL1,x0'
{standard input}:488: Error: unknown or missing system register name at operand 2 -- `mrs x0,TEECR32_EL1'
{standard input}:494: Error: unknown or missing system register name at operand 2 -- `mrs x0,TEEHBR32_EL1'
make[5]: *** [Rules.mk:249: arch/arm/domain.o] Error 1
This turns out to be an intentional change in binutils. ThumbEE was dropped
ahead of ARM v8 (i.e. AArch64).
Xen supports ARM v7+virt extensions so in principle we could #ifdef
CONFIG_ARM_32 to keep it working. However, there was apparently no use of
ThumbEE outside of demo code, so simply drop it.
On ThumbEE capable hardware, unconditionally trap ThumbEE instructions, and
drop the context switching logic for TEE{CR,HBR}32.
Reported-by: Hans van Kranenburg <hans@knorrie.org>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>
xen/arm: Set ThumbEE as not present in PFR0
Force ThumbEE support to not available in the version of the PFR0
register value we present to guest.
Xen does not support ThumbEE and will trap all access to ThumbEE
registers so do not report it being supported if the hardware supports
it.
Fixes: 5bbe1fe413 ("ARM: Drop ThumbEE support")
Signed-off-by: Bertrand Marquis <bertrand.marquis@arm.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>
Reviewed-by: Luca Fancellu <luca.fancellu@arm.com>
Tested-by: Luca Fancellu <luca.fancellu@arm.com>
master commit: 5bbe1fe413
master date: 2025-12-05 18:06:19 +0000
master commit: 1ecb5946bd
master date: 2026-01-05 10:33:03 +0000
Family 0x1a covers both Zen5 and Zen6, but the latter is not believed to be
vulnerable to entrysign.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit bd15fdedaf)
In FRED mode, ERET is stricter than IRET about flags. Notably this means:
* The vm86 bit (bit 17) and IOPL (bits 12,13) must be clear.
* The sticky-1 reserved bit (bit 2) must be set, so dom0_construct() needs to
set X86_EFLAGS_MBS in order for a PV dom0 to start.
* All other reserved bits must be clear.
Xen has been overly lax with reserved bit handling. Adjust
arch_set_info_guest*() and hypercall_iret() which consume flags to clamp the
reserved bits for all guest types.
This is a minor ABI change, but by the same argument as commit
9f892f84c2 ("x86/domctl: Stop using XLAT_cpu_user_regs()"); the reserved
bits would get clamped like this naturally by hardware when the vCPU is run.
The handling of vm86 is also different. Guests under 32bit Xen really could
use vm86 mode, but Long Mode disallows vm86 mode and IRET simply ignores the
bit. Xen's behaviour for a PV32 guest trying to use vm86 mode under a 64bit
Xen is to arrange to deliver #GP at the target of the IRET, rather than to
fail the IRET itself.
However there's no filtering in arch_set_info_guest() itself, and it can't
arrange to queue a #GP at the target, so do the next best thing and fail the
hypercall. This is not expected to create an issue for PV guests, as the
result of such an arch_set_info_guest() previously would be to run supposedly
Real Mode code as Protected Mode code.
This allows PV guests to start when Xen is using FRED mode.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit dbd936248f)
Under FRED, entry_from_pv() handles everything, even system call instructions.
This means more of our logic is written in C now, rather than assembly.
In order to facilitate this, introduce pv_inject_callback(), which reuses
struct trap_bounce infrastructure to inject the syscall/sysenter callbacks.
This in turns requires some !PV compatibility for pv_inject_callback() and
pv_hypercall() which can both be ASSERT_UNREACHABLE().
For each of INT $N, SYSCALL and SYSENTER, FRED gives us interrupted context
which was previously lost. As the guest can't see FRED, Xen has to lose state
in the same way to maintain the prior behaviour.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 76193ef47d)
ERETU can fault for guest reasons, and like IRET needs special handling to
forward the error into the guest.
As this is largely written in C, take the opportunity to better classify the
sources of error, and in particular, not forward errors that are actually
Xen's fault into the guest, opting for a domain crash instead.
Because ERETU does not enable NMIs if it faults, a corner case exists if an
NMI was taken while in guest context, and the ERETU back out faults. Recovery
must involve an ERETS with the interrupted context's NMI flag.
See the comments for full details.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 99edc6c2a0)
Under FRED, entry_from_pv() handles everything. To start with, implement
exception handling in the same manner as entry_from_xen(), although we can
unconditionally enable interrupts after the async/fatal events.
After entry_from_pv() returns, test_all_events() needs to run to perform
exception and interrupt injection. Split entry_FRED_R3() into two and
introduce eretu_exit_to_guest() as the latter half, coming unilaterally from
restore_all_guest().
For all of this, there is a slightly complicated relationship with CONFIG_PV.
entry_FRED_R3() must exist irrespective of CONFIG_PV, because it's the
entrypoint registered with hardware. For simplicity, entry_from_pv() is
always called, but it collapses into fatal_trap() in the !PV case.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 87cfcbe9f0)
When FRED is active, hardware automatically swaps GS when changing privilege,
and the SWAPGS instruction is disallowed.
For native OSes using GS as the thread local pointer this is a massive
improvement on the pre-FRED architecture, but under Xen it makes handling PV
guests more complicated. Specifically, it means that GS_BASE and GS_SHADOW
are the opposite way around in FRED mode, as opposed to IDT mode.
This leads to the following changes:
* In load_segments(), we already load both GSes. Account for FRED in the
SWAP() condition and avoid the path with SWAGS.
* In save_segments(), we need to read GS_SHADOW rather than GS_BASE.
* In toggle_guest_mode(), we need to emulate SWAPGS.
* In {read,write}_msr() which access the live registers, GS_SHADOW and
GS_BASE need swapping.
* In do_set_segment_base(), merge the SEGBASE_GS_{USER,KERNEL} cases and
take FRED into account when choosing which base to update.
SEGBASE_GS_USER_SEL was already an LKGS invocation (decades before FRED)
so under FRED needs to be just a MOV %gs. Simply skip the SWAPGSes.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 9ea7d7f939)
With the shadow stack and exception handling adjustements in place, we can now
activate FRED when appropriate. Note that opt_fred is still disabled by
default until more development is complete.
Introduce init_fred() to set up all the MSRs relevant for FRED. FRED uses
MSR_STAR (entries from Ring3 only), and MSR_FRED_SSP_SL0 aliases MSR_PL0_SSP
when CET-SS is active. Otherwise, they're all new MSRs.
Also introduce init_fred_tss(). At this juncture we need a TSS set up, even
if it is mostly unused. Reinsert the BUILD_BUG_ON() checking the size of the
TSS against 0x67, this time with a more precise comment.
With init_fred() existing, load_system_tables() and legacy_syscall_init()
should only be used when setting up IDT delivery. Insert ASSERT()s to this
effect, and adjust the various init functions to make this property true.
The FRED initialisation path still needs to write to all system table
registers at least once, even if only to invalidate them. Per the
documentation, percpu_early_traps_init() is responsible for switching off the
boot GDT, which also needs doing even in FRED mode.
Finally, set CR4.FRED in traps_init()/percpu_early_traps_init().
Xen can now boot in FRED mode and run a PVH dom0. PV guests still need more
work before they can be run under FRED.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit bbfb30f649)
Under FRED, there's one entrypoint from Ring 3, and one from Ring 0.
FRED gives us a good stack (even for SYSCALL/SYSENTER), and a unified event
frame on the stack with all flags cleared, meaning that all software needs to
do is spill the GPRs with a line of PUSHes. Introduce PUSH_AND_CLEAR_GPRS for
this purpose, along with the matching POP_GPRS.
Introduce entry_FRED_R0() which to a first approximation is complete for all
event handling within Xen.
entry_FRED_R0() needs deriving from entry_FRED_R3(), so introduce a basic
Ring3 handler. There is more work required to make the return-to-guest path
work under FRED.
Also introduce entry_from_{xen,pv}() to be the C level handlers. By simply
copying regs->fred_ss.vector into regs->entry_vector, we can reuse all the
existing fault handlers.
Extend fatal_trap() to render the event type including name, when FRED is
active. This is slightly complicated, because X86_ET_OTHER must not use
vector_name() or SYSCALL and SYSENTER get rendered as #BP and #DB.
This is sufficient to handle all interrupts and exceptions encountered during
development, including plenty of Double Faults.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 0e9cc04453)
FRED doesn't use Supervisor Shadow Stack tokens. This means that:
1) memguard_guard_stack() should not write Supervisor Shadow Stack Tokens.
2) cpu_has_bug_shstk_fracture is no longer relevant when deciding whether to
enable Shadow Stacks or not.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 7634f56625)
We wish to make use of opt_fred earlier on boot, which involves moving
traps_init() earlier, but this comes with several ordering complications.
The feature word containing FRED needs collecting in early_cpu_init(), and
legacy_syscall_init() cannot be moved that early because it relies on the
stubs being allocated, yet must be called ahead of cpu_init() so the SYSCALL
linkage MSRs are set up before being cached.
Delaying legacy_syscall_init() is easy enough based on a system_state check.
Reuse bsp_traps_reinit() to cause a call to legacy_syscall_init() to occur at
the same point as previously.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 8e4775d118)
Lets just say this took an unreasonable amount of time and effort to track
down, when trying to move traps_init() earlier during boot.
When the SYSCALL linkage MSRs are not configured ahead of _svm_cpu_up() on the
BSP, context switch clobbers the later-set-up linkage with the 0's cached
here. Amongst other problems, this causes PV guest to enter at 0 in
supervisor mode on the user stack.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit c2f15b0fff)
Commit 564d261687 ("x86/ctxt-switch: Document and improve GDT handling") put
the initialisation of {,compat_}gdt_l1e into traps_init() but this wasn't a
great choice. Instead, put it in smp_prepare_cpus() which performs the BSP
preparation of variables normally set up by cpu_smpboot_alloc() for APs.
This removes an implicit dependency that prevents traps_init() moving earlier
than move_xen() in the boot sequence.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit a1e6afbf54)
Under FRED, the SWAPGS instruction is disallowed. Therefore we must use the
MSR path instead.
read_registers() is in the show_registers() path, so this change allows Xen to
render it's current state without suffering #UD (and recursing until the stack
guard page is hit).
All hardware with FRED is expected to have some kind of non-serialising access
to these registers.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 3ff1030ea7)
FRED and IDT differ by a Supervisor Token on the base of the shadow stack.
This means that switch_stack_and_jump() needs to discard one extra word when
FRED is active.
Fix a typo in the parameter name, which should be shstk_base.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
(cherry picked from commit 40fbf97177)
FRED provides %cr2 in the the stack frame, avoiding the need to read %cr2
manually.
Rename do_page_fault() to handle_PF(), and update it to take cr2, still named
addr for consistency.
Introduce a new handle_PF_IDT() which reads %cr2 and conditionally re-enables
interrupts.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 4153eb7660)
FRED provides PENDING_DBG in the the stack frame, avoiding the need to read
%dr6 manually.
Rename do_debug() to handle_DB(), and update it to take a dbg field using
positive polarity.
Introduce a new handle_DB_IDT() which reads %dr6.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit d9974d7860)
This is really a rearrangement to make adding FRED support easier.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 524f3fa35e)
Under FRED, SETSSBSY is disallowed, and we want to be setting up FRED prior to
setting up shadow stacks. As we still need Supervisor Tokens in IDT mode, we
need mode-specific logic to establish SSP.
In FRED mode, write a Restore Token, RSTORSSP it, and discard the resulting
Previous-SSP token.
No change outside of FRED mode.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 3037d8b7eb)
It turns out that using the higher level helpers adjacent like this leads to
terrible code generation. Due to -fno-strict-aliasing, the store into state
invalidates the read_cr4() address calculation (which is really cpu_info->cr4
under the hood), meaning that it can't be hoisted.
As a result we get "locate the top of stack block, get cr4, and see if
FSGSBASE is set" repeated 3 times, and an unreasonable number of basic blocks.
Hoist the calculation manually, which results in two basic blocks.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 42a0709f37)
... and rdmsr() while here.
Most of these accesses are in fastpaths and do not need serialising behaviour,
but the write side is serialising on all Intel hardware as well as older AMD
hardware.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 6b448a92a3)
Right now they're inline in {read,write}_gs_shadow(), but we're going to need
to use these elsewhere to support FRED.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 9900679fa9)
Mirroring the cleanup to rdmsr(), do the same to wrmsr(). It now has the same
API as wrmsrl(), but we'll want to drop that wrapper in due course.
It's telling that almost all remaining users pass in 0. Most are converted
directly to WRMSRNS, but a few are not.
MSR_VIRT_SPEC_CTRL is unconditionally intercepted and is orders of magnitude
more expensive than just serialising. In disable_lapic_nmi_watchdog(), the P4
case won't run on hardware which has anything more than plain WRMSR.
For CTR_WRITE() in op_model_athlon.c there is a logical change in behaviour,
but it's fixing a bug. Peformance counters typically get written to -(count)
as they generate an interrupt on overflow. The performance counters even in
the K8 were 48 bits wide, and this wrmsr() not being a wrmsrl() appears to
have been an oversight in commit b5103d692a ("x86 oprofile: use
rdmsrl/wrmsrl") which converted all other users, and appears to be the last
time there was an attempt to unify the MSR APIs.
No practical change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 389347a75f)
We want a consistent MSR API, and these want to be named rdmsr() and wrmsr(),
but not with their current APIs. The current rdmsr() flavours writing to
their parameters by name makes code that reads like invalid C, and is
unergonomic to use in lots of cases.
Change the API, and update the callers all in one go. Where appropriate,
update the write side to wrmsrns() as per the recommendation.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit ba342df56a)
Multiple downstream distros have tried passing discrete CPIO archives and
tripped over this not working. It turns out to be easy to support, so do so.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Tested-by: Teddy Astie <teddy.astie@vates.tech>
[jb: doc change dropped as inapplicable to the older form]
master commit: 878a9cfa45
master date: 2026-03-03 15:15:53 +0000
For INT $N instructions (besides $0x80 for which there is a dedicated fast
path), handling is mostly fault-based because of DPL0 gates in the IDT. This
means that when the guest kernel allows the instruction too, Xen must
increment %rip to the end of the instruction before passing a trap to the
guest kernel.
When an INT $N instruction has a prefix, it's longer than two bytes, and Xen
will deliver the "trap" with %rip pointing into the middle of the instruction.
Introduce a new pv_emulate_sw_interrupt() which uses x86_insn_length() to
determine the instruction length, rather than assuming two.
This is a change in behaviour for PV guests, but the prior behaviour cannot
reasonably be said to be intentional.
This change does not affect the INT $0x80 fastpath. Prefixed INT $N
instructions occur almost exclusively in test code or exploits, and INT $0x80
appears to be the only user-usable interrupt gate in contemporary PV guests.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: a934a600c4
master date: 2026-03-03 15:15:53 +0000
Alpine Linux, when using --enable-systemd to get the init files, fails with:
tools/include/xen-sd-notify.h:69:3: error: call to undeclared library
function 'memcpy' with type 'void *(void *, const void *, unsigned long)';
ISO C99 and later do not support implicit function declarations
[-Wimplicit-function-declaration]
69 | memcpy(socket_addr.sun.sun_path, socket_path, path_length);
| ^
This will be down to using musl rather than glibc. Include the appropriate
header.
Fixes: 78510f3a15 ("tools: Import stand-alone sd_notify() implementation from systemd")
Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Acked-by: Anthony PERARD <anthony.perard@vates.tech>
(cherry picked from commit 8efff5a69a)
As amd_init_de_cfg() states, it's only safe for there to be one location
writing to DE_CFG. This happens to be a latent bug rather than a real one
because Fam12h CPUs aren't SMT-capable. Nevertheless, group it together with
the other DE_CFG modifications.
This removes a printk() which is not noteworthy, and skips the adjustment
entirely under virt, where the attempted write wouldn't have stuck anyway.
Fixes: d0c75dc4c0 ("x86/amd: Fix race editing DE_CFG")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
master commit: f49bbd301b
master date: 2026-01-27 13:59:12 +0000
XENMEM_claim_pages can be issued on a domain in the later stages of
domain_kill(). In that case, the claimed memory is leaked, as there's no way
to subsequently release the claim.
Claims are intended for use during domain construction; to reserve sufficient
RAM to construct the domain fully. There's no legitimate reason to be calling
it on a dying domain.
Fixes: 65c9792df6 ("mmu: Introduce XENMEM_claim_pages (subop of memory ops)")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 2379ca04fe
master date: 2025-12-17 17:35:24 +0000
We have two different functions explaining that DE_CFG is Core-scoped and that
writes are racy but happen to be safe. This is only true when there's one of
them.
Introduce amd_init_de_cfg() to be the singular function which writes to
DE_CFG, modelled after the logic we already have for BP_CFG.
While reworking amd_check_zenbleed() into a simple predicate used by
amd_init_de_cfg(), fix the microcode table. The 'good_rev' was specific to an
individual stepping and not valid to be matched by model, let alone a range.
The only CPUs incorrectly matched that I can locate appear to be
pre-production, and probably didn't get Zenbleed microcode.
Rework amd_init_lfence() to be amd_init_lfence_dispatch() with only the
purpose of configuring X86_FEATURE_LFENCE_DISPATCH in the case that it needs
synthesising. Run it on the BSP only and use setup_force_cpu_cap() to prevent
the bit disappearing on a subseuqent CPUID rescan.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: d0c75dc4c0
master date: 2025-12-01 16:20:41 +0000
This was potentially helpful when the chickenbit was the only mitigation and
microcode had not been released, but that was two years ago.
Zenbleed microcode has been avaialble since December 2023, and the subsequent
Entrysign signature vulnerability means that firmware updates block OS-loading
and more OS-loadable microcode will be produced for Zen2.
i.e. the Zenbleed fix is not going to appear at runtime these days.
No practical change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
master commit: 5cd1ac1575
master date: 2025-11-27 18:22:20 +0000
The xen-ucode utility is sensitive to the overall error as -EEXIST is a
special case for success, but the real error can get clobbered with -EBUSY.
This can be demonstrated most easily by force loading an old microcode, which
should yield -EIO but yields -EBUSY:
# xen-ucode /lib/firmware/amd-ucode/microcode_amd_fam17h.bin --force
Failed to update microcode. (err: Device or resource busy)
(XEN) 256 cores are to update their microcode
(XEN) microcode: CPU0 update rev 0x830107d to 0x830107c failed, result 0x830107d
(XEN) Late loading aborted: CPU0 failed to update ucode: -5
wait_for_state() returns false on encountering LOADING_EXIT. Right now, this
is always transformed into -EBUSY and passed back to callers.
However, control_thread_fn() can move directly to this state in the case of an
early error; it is not an error condition for APs, but the latest write into
stopmachine_data.fn_result wins, causing the real error, -EIO, to get
clobbered with -EBUSY.
Drop all the -EBUSY's, and treat hitting LOADING_EXIT as a success case. This
causes only a single error to be returned through stop_machine_run(), and
preserves the -EIO
# xen-ucode /lib/firmware/amd-ucode/microcode_amd_fam17h.bin --force
Failed to update microcode. (err: Input/output error)
(XEN) 256 cores are to update their microcode
(XEN) microcode: CPU0 update rev 0x830107d to 0x830107c failed, result 0x830107d
(XEN) Late loading aborted: CPU0 failed to update ucode: -5
Fixes: 5ed12565aa ("microcode: rendezvous CPUs in NMI handler and load ucode")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: a405bf42ed
master date: 2025-11-24 15:17:39 +0000
The latest oxenstored from Xapi-project fails to start up:
launch-xenstore[1201]: Starting /usr/sbin/oxenstored...
launch-xenstore[1222]: Fatal error: exception
Dynlink.Error (Dynlink.Cannot_open_dll "Dynlink.Error (Dynlink.Cannot_open_dll
\"Failure(\\\"/usr/libexec/xen//ocaml/xsd_glue/xenctrl_plugin/domain_getinfo_v1.cmxs:
undefined symbol: xc_domain_getinfo_single\\\")\")")
This is because domain_getinfo_v1.cmxs isn't dynamically linked correctly.
Fill in the correct variable, and remove the xen prefix from xenctrl.
Reported-by: Edwin Török <edwin.torok@citrix.com>
Suggested-by: Edwin Török <edwin.torok@citrix.com>
Fixes: a6576011a4 ("ocaml/libs: Implement a dynamically-loaded plugin for Xenctrl.domain_getinfo")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Christian Lindig <christian.lindig@cloud.com>
Release-Acked-By: Oleksii Kurochko <oleksii.kurochko@gmail.com>
When Entrysign has been mitigated in firwmare, it is believed to be safe to
rely on the CPU patchloader again. This avoids us needing to maintain the
digest table for all new microcode indefinitely.
Relax the digest check when firmware looks to be up to date, and leave behind
a clear message when not.
When the Zen6 (also Fam1ah processors) model numbers are known, they'll want
excluding from the range.
This is best-effort only. If a malicious microcode has been loaded prior to
Xen running, then all bets are off.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Release-Acked-By: Oleksii Kurochko <oleksii.kurochko@gmail.com>
After initial publication, the SB-7033 / CVE-2024-36347 bulletin was updated
to list Zen5 CPUs as vulnerable. Use Fam1ah as an upper bound, and adjust the
command line documentation.
When the Zen6 (also Fam1ah processors) model numbers are known, they'll want
excluding from the range.
Fixes: 630e8875ab ("x86/ucode: Perform extra SHA2 checks on AMD Fam17h/19h microcode")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Release-Acked-By: Oleksii Kurochko <oleksii.kurochko@gmail.com>
For Zen3-5 microcode blobs signed with the updated signature scheme, the
checksum field has been reused to be a min_revision field, referring to the
microcode revision which fixed Entrysign (SB-7033, CVE-2024-36347).
Cross-check this when trying to load microcode, but allow --force to override
it. If the signature scheme is genuinely different, a #GP will occur.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Release-Acked-By: Oleksii Kurochko <oleksii.kurochko@gmail.com>
EIO is not the only error that ucode_ops.apply_microcode() can produce.
EINVAL, EEXISTS and ENXIO can be generated too, each of which mean that Xen is
unhappy in some way with the proposed blob.
Some of these can be bypassed with --force, which will cause the parallel load
to be attempted.
Fixes: 5ed12565aa ("microcode: rendezvous CPUs in NMI handler and load ucode")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Release-Acked-By: Oleksii Kurochko <oleksii.kurochko@gmail.com>
With the exception of the custom IBT job, copy all Debian 12 jobs making
Debian 13 versions, then trim the Debian 12 ranconfig jobs.
Update the test jobs using Debian 12 to use 13.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Denis Mukhin <dmukhin@ford.com>
Reviewed-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
Marek noticed that some builds were failing with:
+ cd dist/install
+ find
+ cpio -R 0:0 -o -H newc
./automation/scripts/build: line 111: cpio: command not found
+ gzip
but succeeding overall, and producing a zero length xen-tools.cpio.gz as an
artefact.
In fact, it's all of:
archlinux:current
debian:12-x86_32
fedora:41
opensuse:tumbleweed
ubuntu (all versions)
Add cpio into all of these containers, including opensuse leap for good
measure, and use pipefail in the build script.
Fixes: 4611ae6fb8 ("CI: save toolstack artifact as cpio.gz")
Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Denis Mukhin <dmukhin@ford.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
Randconfig with GCC-14 (Debian Trixie) found:
In file included from arch/x86/x86_emulate/x86_emulate.c:11,
from arch/x86/x86_emulate.c:27:
arch/x86/x86_emulate/x86_emulate.c: In function 'x86_emulate':
arch/x86/x86_emulate/private.h:482:8: error: Too many conditions (found 826); giving up coverage [-Werror=coverage-too-many-conditions]
482 | ({ if ( (p) ) { \
| ^
arch/x86/x86_emulate/x86_emulate.c:1283:5: note: in expansion of macro 'generate_exception_if'
1283 | generate_exception_if((mode_vif() &&
| ^~~~~~~~~~~~~~~~~~~~~
which is a consequence of having a new enough compiler to allow
CONFIG_CONDITION_COVERAGE in to the mix.
In the short term make warning non-fatal, but this will need fixing
properly in due course.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
The OVMF package in Debian Trixie has _4M suffixes on the files. Have
scripts/include/xtf-x86-64-efi check for this before falling back to no
suffix.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Denis Mukhin <dmukhin@ford.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
cpio needs to be in Tools (general) now that it's used by the general build
script. Merge the rest of the test phase jobs into one group, to avoid being
overly fine-grain.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Denis Mukhin <dmukhin@ford.com>
Reviewed-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
Everything works fine with Debian 13. Provide two new build jobs (for a total
of 6), and update the test jobs.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Denis Mukhin <dmukhin@ford.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
Everything works fine with Debian 13. Provide two new build jobs, and update
both the randconfig the test jobs.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
We have a mix of root and non-root containers, and are trying to become
rootless. This can cause the local CPIO fragements to end up being user:user
in the test environment.
Nothing seems to go wrong so far, but it's a trap waiting to happen.
Make everything consistently root for the initrds, irrespective of the
rootness of the container the test is running in.
No practical change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Denis Mukhin <dmukhin@ford.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
... instead of having them split across multiple.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Drop unused or stale lines.
* While it's necessary to have .git and .hg in each others ignore files if
using multiple SCMs (as we did for a while), they should not be in their
own. The mercurial files were dropped in commit ba5bae659d ("Drop
remains of prior SCMs") (2023).
* The ignore for LibVNCServer* was added by commit a090ca495e ("VNC pasword
authentication support for the paravirt framebuffer server.") (2006) but
without justification or any obvious reason.
* The ignore for tools/misc/lowmemd was added in commit c812282081 ("Low
mem virq incremental adjustments") (2012), but xen-lowmemd (from the same
author) already existed and was ignored properly.
* tools/libs/guest/xc_* were added in commit af6c78d9dc ("tools: move
libxenctrl below tools/libs") for bisectibility, but should have been
dropped in the following change, commit e3dd624e48 ("tools/libxc: move
libxenguest to tools/libs/guest").
* tools/debugger/xenitp/ was dropped in commit e567964a54 ("tools: drop
ia64 support") (2012).
* tools/debugger/gdb/ was dropped in commit
baa1aae9cf ("tools/debugger/gdb: Remove gdb") (2010).
* tools/misc/cpuperf/ was dropped in commit ae95fdf65a ("[TOOLS] Remove the
'cpuperf' misc tool.") (2006).
* tools/misc/xc_shadow was dropped in commit 7133144e3a ("Remove xc_shadow
tool") (2007).
* tools/misc/xen_cpuperf was dropped in commit 60eba9b0d2 ("Delete some
unused tools") (2004).
* tools/misc/xen-tmem-list-parse was dropped in commit c588c002cc ("tools:
remove tmem code and commands") (2018).
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
One aspect of the old ffs() infrastructure was the use of TZCNT without a
CPUID check. Given no obvious justification, I dropped it during the cleanup.
It turns out there is a good reason, on all but the most recent AMD CPUs.
Reinstate the use of "blind" TZCNT when safe to do so. This happens to be
preferentially in loops where a repeated saving of 5-6 uops becomes far more
relevant than a one-off scenario. Leave an explanation of why.
It is not safe to perform this transformation for BSR and LZCNT, because they
count from opposite ends of the input operand. Furthermore, this incorrect
transform was not caught by the selftests.
Extend the selftests with test_for_each_set_bit_reverse() as that exercises
the "x known non-zero" optimsiation path in x86's helpers. Adjust the
existing test_for_each_set_bit() to intentionally use an asymmetric input bit
pattern, otherwise "counting from the wrong end" bugs continue to slip by.
No functional change.
Fixes: 989e5f08d3 ("x86/bitops: Improve arch_ffs() in the general case")
Fixes: 5ed26fc076 ("xen/bitops: Implement ffsl() in common logic")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
It is not obvious at first glance, but this is dead logic.
On Intel, xAPIC (which is what modern_apic() is really checking for) predates
64bit support, while the Family 0xf check on AMD is the K8 processor.
Simply drop the logic, rather than trying to adjust vendor/family logic.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
This is a port of Linux commit 517234446c1a ("x86/apic: Get rid of
get_physical_broadcast()") to Xen. Thomas Gleixner notes:
There is no point for this function. The only case where this is used is
when there is no XAPIC available, which means the broadcast address is 0xF.
In Linux, users of get_physical_broadcast() have already been hidden behind
CONFIG_X86_32 suggesting we can drop all of this, but that's a task for some
other time.
In Xen as with Linux, setup_ioapic_ids_from_mpc() and io_apic_get_unique_id()
only apply to pre-xAPIC cases, so can use a broadcast ID of 0xf. The only
other user is __print_IO_APIC() for diagnostics, which can simply drop the
check.
No functional change.
Link: https://lore.kernel.org/r/20240212154639.057209154@linutronix.de
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Jan reports the following exception when using the cycle debugging:
Feature IBRSB, seen [IBRSB, STIBP, INTEL_PSFD, EIBRS, IPRED_CTRL, RRSBA_CTRL, RRSBA, BHI_CTRL], to_process [SSBD]
Traceback (most recent call last):
File "/local/xen.git/xen/../xen/tools/gen-cpuid.py", line 594, in <module>
sys.exit(main())
^^^^^^
File "/local/xen.git/xen/../xen/tools/gen-cpuid.py", line 588, in main
crunch_numbers(state)
File "/local/xen.git/xen/../xen/tools/gen-cpuid.py", line 366, in crunch_numbers
(state.names[feat], repl(seen), repl(to_process)))
^^^^^^^^^^^^^^^^
File "/local/xen.git/xen/../xen/tools/gen-cpuid.py", line 364, in repl
return "[" + ", ".join((state.names[x] for x in l)) + "]"
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/local/xen.git/xen/../xen/tools/gen-cpuid.py", line 364, in <genexpr>
return "[" + ", ".join((state.names[x] for x in l)) + "]"
~~~~~~~~~~~^^^
KeyError: 534
make[2]: *** [/local/xen.git/xen/include/xen/lib/x86/Makefile:9: cpuid-autogen.h] Error 1
This is caused by commit ce8c930851 ("x86/cpu-policy: MSR_ARCH_CAPS feature
names") being rather lazy and marking dependenices on unknown features.
Introduce a helper to pick the known features in a range, and use it for
ARCH_CAPS.
Additionally, remove trailing whitespace and an unnecessary line continuation
from the debug print.
Reported-by: Jan Beulich <jbeulich@suse.com>
Fixes: ce8c930851 ("x86/cpu-policy: MSR_ARCH_CAPS feature names")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
FRED and IDT differ by a Supervisor Token on the base of the shstk. This
means that the value they load into MSR_PL0_SSP differs by 8.
s3_resume() in particular has logic which is otherwise invariant of FRED mode,
and must not clobber a FRED MSR_PL0_SSP with an IDT one.
This also simplifies the AP path too.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Under FRED, SETSSBSY is disallowed, and we want to be setting up FRED prior to
setting up shadow stacks. Luckily, RSTORSSP will also work in this case.
This involves a new type of shadow stack token, the Restore Token, which is
distinguished from the Supervisor Token by pointing to the adjacent slot on
the shadow stack rather than pointing at itself.
In the short term, this logic still needs to load MSR_PL0_SSP.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
percpu_early_traps_init() will shortly be setting CR4.FRED. This requires
that cpu_info->cr4 is already set up, and that the enablement of CET doesn't
truncate X86_CR4_FRED back out because of using 32bit logic.
For __high_start(), defer re-loading XEN_MINIMAL_CR4 until after %rsp is set
up and we can store the result in the cr4 field too.
For s3_resume(), explicitly re-load XEN_MINIMAL_CR4. Later when loading all
features, use the mmu_cr4_features variable which is how the rest of Xen
performs this operation.
No functional change, yet.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
... disabled by default. There is a lot of work before FRED can be enabled by
default.
One part of FRED, the LKGS (Load Kernel GS) instruction, is enumerated
separately but expected to be mandatory as FRED disallows the SWAPGS
instruction. Normally, we'd have to check both CPUID bits, but Xen does not
use GS like most other software, and can manage without LKGS.
FRED formally removes the use of Ring1 and Ring2, meaning we cannot run 32bit
PV guests. As already done with CET, disable PV32 if using FRED, except in
shim mode where FRED is disabled by default.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
The FRED on-stack format is larger than the IDT format, but is by and large
compatible. FRED reuses space above cs and ss for extra metadata, some of
which is purely informational, and some of which causes additional effects in
ERET{U,S}.
Follow Linux's choice of naming for fred_{c,s}s structures, to make it very
clear at the point of use that it's dependent on FRED.
There is also the event data field and reserved fields, but we cannot include
these in struct cpu_user_regs without reintroducing OoB structure accesses in
the non-FRED case. See commit 6065a05adf ("x86/traps: 'Fix' safety of
read_registers() in #DF path"). for more details.
Instead, use a new struct fred_info and position it suitably in struct
cpu_info. This boundary will be loaded into MSR_FRED_RSP_SL0, and must be
64-byte aligned.
This does add 16 bytes back into struct cpu_info, undoing the saving we made
by dropping the vm86 data segment selectors.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Of note, CR4.FRED is bit 32 and cannot enabled outside of 64bit mode.
Most supported toolchains don't understand the FRED instructions yet.
Nevertheless, ERETU and ERETS are easy to wrap (they encoded as REPZ/REPNE
CLAC), while LKGS turns out not to be needed by Xen.
We will need some alternatives based on FRED, so add a synthetic
X86_FEATURE_XEN_FRED.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
There's no family check gating intel_init_ppin(), making it incorrect to use
on non Fam6 CPUs. Switch to using VFM.
Emerald Rapids is the final CPU to have PPIN but lack the the architectural
enumeration, so include it too.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
GCC 5.1 is the minimum supported toolchain version now. Drop the workaround
for the PIC hard register in earlier versions.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
... on capable toolchains.
This avoids needing to hold rc in a register across the RDMSR, and in most
cases removes direct testing and branching based on rc, as the fault label can
be rearranged to directly land on the out-of-line block.
There is a subtle difference in behaviour. The old behaviour would, on fault,
still produce 0's and write to val.
The new behaviour only writes val on success, and write_msr() is the only
place where this matters. Move temp out of switch() scope and initialise it
to 0.
While it is possible to retain the old behaviour, it's not great to do so
because the compiler cannot optimise out the dead store when it's not to a
local function variable, and Xen has a lot of msr infrastructure which passes
a val pointer through the call-tree. We have compilers with ASM_GOTO_OUTPUT
in CI, and they do notice.
Resolves: https://gitlab.com/xen-project/xen/-/work_items/217
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
... in preparation to be able to use asm goto.
Notably this mean that the value parameter must be taken by pointer rather
than by value.
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Andrew Cooper