There is a bug in commit 5e4b419966 ("xen: credit2: only reset
credit on reset condition"). In fact, the aim of that commit was to
make sure that we do not perform too many credit reset operations
(which are not super cheap, and in an hot-path). But the check used
to determine whether a reset is necessary was the wrong one.
In fact, knowing just that some vCPUs have been skipped, while
traversing the runqueue (in runq_candidate()), is not enough. We
need to check explicitly whether the first vCPU in the runqueue
has a negative amount of credit.
Since a trace record is changed, this patch updates xentrace format file
and xenalyze as well
This should be backported.
Signed-off-by: Dario Faggioli <dfaggioli@suse.com>
Acked-by: George Dunlap <george.dunlap@citrix.com>
master commit: dae7b62e97
master date: 2020-04-03 10:46:53 +0200
There have been report of stalls of guest vCPUs, when Credit2 was used.
It seemed like these vCPUs were not getting scheduled for very long
time, even under light load conditions (e.g., during dom0 boot).
Investigations led to the discovery that --although rarely-- it can
happen that a vCPU manages to run for very long timeslices. In Credit2,
this means that, when runtime accounting happens, the vCPU will lose a
large quantity of credits. This in turn may lead to the vCPU having less
credits than the idle vCPUs (-2^30). At this point, the scheduler will
pick the idle vCPU, instead of the ready to run vCPU, for a few
"epochs", which often times is enough for the guest kernel to think the
vCPU is not responding and crashing.
An example of this situation is shown here. In fact, we can see d0v1
sitting in the runqueue while all the CPUs are idle, as it has
-1254238270 credits, which is smaller than -2^30 = −1073741824:
(XEN) Runqueue 0:
(XEN) ncpus = 28
(XEN) cpus = 0-27
(XEN) max_weight = 256
(XEN) pick_bias = 22
(XEN) instload = 1
(XEN) aveload = 293391 (~111%)
(XEN) idlers: 00,00000000,00000000,00000000,00000000,00000000,0fffffff
(XEN) tickled: 00,00000000,00000000,00000000,00000000,00000000,00000000
(XEN) fully idle cores: 00,00000000,00000000,00000000,00000000,00000000,0fffffff
[...]
(XEN) Runqueue 0:
(XEN) CPU[00] runq=0, sibling=00,..., core=00,...
(XEN) CPU[01] runq=0, sibling=00,..., core=00,...
[...]
(XEN) CPU[26] runq=0, sibling=00,..., core=00,...
(XEN) CPU[27] runq=0, sibling=00,..., core=00,...
(XEN) RUNQ:
(XEN) 0: [0.1] flags=0 cpu=5 credit=-1254238270 [w=256] load=262144 (~100%)
We certainly don't want, under any circumstance, this to happen.
Let's, therefore, define a minimum amount of credits a vCPU can have.
During accounting, we make sure that, for however long the vCPU has
run, it will never get to have less than such minimum amount of
credits. Then, we set the credits of the idle vCPU to an even
smaller value.
NOTE: investigations have been done about _how_ it is possible for a
vCPU to execute for so much time that its credits becomes so low. While
still not completely clear, there are evidence that:
- it only happens very rarely,
- it appears to be both machine and workload specific,
- it does not look to be a Credit2 (e.g., as it happens when
running with Credit1 as well) issue, or a scheduler issue.
This patch makes Credit2 more robust to events like this, whatever
the cause is, and should hence be backported (as far as possible).
Reported-by: Glen <glenbarney@gmail.com>
Reported-by: Tomas Mozes <hydrapolic@gmail.com>
Signed-off-by: Dario Faggioli <dfaggioli@suse.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>
master commit: 36f3662f27
master date: 2020-04-03 10:45:43 +0200
cpu_request_microcode() doesn't know the buffer is at least 4 bytes long
before inspecting UCODE_MAGIC.
install_equiv_cpu_table() doesn't know the boundary of the buffer it is
interpreting as an equivalency table. This case was clearly observed at one
point in the past, given the subsequent overrun detection, but without
comprehending that the damage was already done.
Make the logic consistent with container_fast_forward() and pass size_left in
to install_equiv_cpu_table().
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 718d143200
master date: 2020-04-01 14:00:12 +0100
The involved comparison was, very likely inadvertently, converted from
>= to > when making changes unrelated to the actual family range.
Fixes: 9841eb71ea ("x86/cpuid: Drop a guests cached x86 family and model information")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Paul Durrant <paul@xen.org>
master commit: 5d515b1c29
master date: 2020-04-01 12:28:30 +0200
find_equiv_cpu_id() loops until it finds a 0 installed_cpu entry. Well formed
AMD microcode containers have this property.
Extend the checking in install_equiv_cpu_table() to reject tables which don't
have a sentinal at the end.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 1f97b6b9f1
master date: 2020-03-27 13:13:26 +0000
In the unlikley case that patch application completes, but the resutling
revision isn't expected, sig->rev doesn't get updated to match reality.
It will get adjusted the next time collect_cpu_info() gets called, but in the
meantime Xen might operate on a stale value. Nothing good will come of this.
Rewrite the logic to always update the stashed revision, before worrying about
whether the attempt was a success or failure.
Take the opportunity to make the printk() messages as consistent as possible.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Wei Liu <wl@xen.org>
master commit: d2a0a96cf7
master date: 2020-03-26 18:57:45 +0000
args.preempted is meaningless here as it doesn't signal whether the
hypercall was preempted before. Use start_extent instead which is
correct (as long as the hypercall was invoked in a "normal" way).
Signed-off-by: Igor Druzhinin <igor.druzhinin@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
master commit: 76dbabb59e
master date: 2020-03-18 12:55:54 +0100
Just like VMX'es lbr_tsx_fixup_check() the respective CPUID bit should
be consulted first.
Reported-by: Farrah Chen <farrah.chen@intel.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: 15c39c7c91
master date: 2020-02-26 17:35:48 +0100
amd_iommu_get_paging_mode() expects a count, not a "maximum possible"
value. Prior to b4f042236a dropping the reference, the use of our mis-
named "max_page" in amd_iommu_domain_init() may have lead to such a
misunderstanding. In an attempt to avoid such confusion in the future,
rename the function's parameter and - while at it - convert it to an
inline function.
Also replace a literal 4 by an expression tying it to a wider use
constant, just like amd_iommu_quarantine_init() does.
Fixes: ea38867831 ("x86 / iommu: set up a scratch page in the quarantine domain")
Fixes: b4f042236a ("AMD/IOMMU: Cease using a dynamic height for the IOMMU pagetables")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: b75b3c62fe
master date: 2020-03-16 11:24:29 +0100
This is an Intel-only, read-only MSR related to microcode loading. Expose it
in similar circumstances as the PATCHLEVEL MSR.
This should have been alongside c/s 013896cb8b "x86/msr: Fix handling of
MSR_AMD_PATCHLEVEL/MSR_IA32_UCODE_REV"
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 691265f960
master date: 2020-02-20 17:29:50 +0000
Checking just the first and last page is not sufficient (and redundant
for single-page regions). As we don't need to care about IA64 anymore,
use an x86-specific function to get this done without looping over each
individual page.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
master commit: d6573bc6e6
master date: 2020-02-18 16:21:19 +0100
The value of the counter represents the number of nanoseconds
since host boot. That means the correct frequency is always 1GHz.
This inconsistency caused time to go slower in PV shim on most
platforms.
Signed-off-by: Igor Druzhinin <igor.druzhinin@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
master commit: c52bd545de
master date: 2020-02-14 18:01:52 +0000
Similarly to S3, platform time needs to be saved on guest suspend
and restored on resume respectively. This should account for expected
jumps in PV clock counter value after resume. time_suspend/resume()
are safe to use in PVH setting as is since any existing operations
with PIT/HPET that they do would simply be ignored if PIT/HPET is
not present.
Additionally, add resume callback for Xen PV clocksource to avoid
its breakage on migration.
Signed-off-by: Igor Druzhinin <igor.druzhinin@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
master commit: a7a3ecd82e
master date: 2020-02-14 18:01:52 +0000
Just before smp_send_stop() re-enables interrupts when shutting down
for reboot or kexec, it calls __stop_this_cpu() which in turn calls
disable_local_APIC(), which puts the APIC back in to the mode Xen found
it in at boot.
If that means turning x2APIC off and going back into xAPIC mode, then
a timer interrupt occurring just after interrupts come back on will
lead to a GP# when apic_timer_interrupt() attempts to ack the IRQ
through the EOI register in x2APIC MSR 0x80b:
(XEN) Executing kexec image on cpu0
(XEN) ----[ Xen-4.14-unstable x86_64 debug=n Not tainted ]----
(XEN) CPU: 0
(XEN) RIP: e008:[<ffff82d08026c139>] apic_timer_interrupt+0x29/0x40
(XEN) RFLAGS: 0000000000010046 CONTEXT: hypervisor
(XEN) rax: 0000000000000000 rbx: 00000000000000fa rcx: 000000000000080b
...
(XEN) Xen code around <ffff82d08026c139> (apic_timer_interrupt+0x29/0x40):
(XEN) c0 b9 0b 08 00 00 89 c2 <0f> 30 31 ff e9 0e c9 fb ff 0f 1f 40 00 66 2e 0f
...
(XEN) Xen call trace:
(XEN) [<ffff82d08026c139>] R apic_timer_interrupt+0x29/0x40
(XEN) [<ffff82d080283825>] S do_IRQ+0x95/0x750
...
(XEN) [<ffff82d0802a0ad2>] S smp_send_stop+0x42/0xd0
We can't clear the global x2apic_enabled variable in disable_local_APIC()
itself because that runs on each CPU. Instead, correct it (by using
current_local_apic_mode()) in smp_send_stop() while interrupts are still
disabled immediately after calling __stop_this_cpu() for the boot CPU,
after all other CPUs have been stopped.
cf: d639bdd9bb ("x86/apic: Disable the LAPIC later in smp_send_stop()")
... which didn't quite fix it completely.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
master commit: 8b1002ab03
master date: 2020-02-14 18:01:52 +0000
The written ABI states that %es will be set up, but libxc doesn't do so. In
practice, it breaks `rep movs` inside guests before they reload %es.
The written ABI doesn't mention %ss, but libxc does set it up. Having %ds
different to %ss is obnoxous to work with, as different registers have
different implicit segments.
Modify the spec to state that %ss is set up as a flat read/write segment.
This a) matches the Multiboot 1 spec, b) matches what is set up in practice,
and c) is the more sane behaviour for guests to use.
Fixes: 68e1183411 ('libxc: introduce a xc_dom_arch for hvm-3.0-x86_32 guests')
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Wei Liu <wl@xen.org>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
x86/pvh: Adjust dom0's starting state
Fixes: b25fb1a04e "xen/pvh: Fix segment selector ABI"
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Wei Liu <wl@xen.org>
Acked-by: Jan Beulich <jbeulich@suse.com>
master commit: b25fb1a04e
master date: 2020-02-10 15:26:09 +0000
master commit: 6ee1031362
master date: 2020-02-11 11:04:26 +0000
There are hypercall handling paths (EFI ones are what this was found
with) needing to allocate buffers of a caller specified size. This is
generally fine, as our page allocator enforces an upper bound on all
allocations. However, certain extremely large sizes could, when adding
in allocator overhead, result in an apparently tiny allocation size,
which would typically result in either a successful allocation, but a
severe buffer overrun when using that memory block, or in a crash right
in the allocator code.
Reported-by: Ilja Van Sprundel <ivansprundel@ioactive.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>
master commit: cf38b4926e
master date: 2020-02-06 09:53:12 +0100
Commit 1f4eb9d27d ("EFI: fix getting EFI variable list on some
systems") switched to using the caller provided size for the copy-out
without making sure the copied buffer is properly scrubbed.
Reported-by: Ilja Van Sprundel <ivansprundel@ioactive.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>
master commit: 4783ee894f
master date: 2020-02-06 09:52:33 +0100
A malicious guest given permission to invoke XENPF_efi_runtime_call may
play with the strings underneath Xen sizing them and copying them in.
Guard against this by re-checking the copyied in data for consistency
with the initial sizing. At the same time also check that the actual
copy-in is in fact successful, and switch to the lighter weight non-
checking flavor of the function.
Reported-by: Ilja Van Sprundel <ivansprundel@ioactive.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>
master commit: ad38db5852
master date: 2020-02-06 09:51:17 +0100
The HVM context may not fill up the full buffer passed by the caller.
While we report corectly the size of the context, we will still be
copying back the full size of the buffer.
As the buffer is allocated through xmalloc(), we will be copying some
bits from the previous allocation.
Only copy back the part of the buffer used by the HVM context to prevent
any leak.
Note that per XSA-72, this is not a security issue.
Signed-off-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 41d8869003
master date: 2020-01-31 18:51:38 +0000
... and enable it after exiting S-state. Otherwise accumulated
output in serial buffer might easily trigger the watchdog if it's
still enabled after entering sync transmission mode.
The issue observed on machines which, unfortunately, generate non-0
output in CPU offline callbacks.
Signed-off-by: Igor Druzhinin <igor.druzhinin@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 5e08f5f56c
master date: 2020-01-29 15:06:10 +0100
The Intel SDM states:
"When an illegal vector value (0 to 15) is written to a LVT entry and
the delivery mode is Fixed (bits 8-11 equal 0), the APIC may signal an
illegal vector error, without regard to whether the mask bit is set or
whether an interrupt is actually seen on the input."
And that's exactly what's currently done in disconnect_bsp_APIC when
virt_wire_setup is true and LVT LINT0 is being masked. By writing only
APIC_LVT_MASKED Xen is actually setting the vector to 0 and the
delivery mode to Fixed (0), and hence it triggers an APIC error even
when the LVT entry is masked.
This would usually manifest when Xen is being shut down, as that's
where disconnect_bsp_APIC is called:
(XEN) APIC error on CPU0: 40(00)
Fix this by calling clear_local_APIC prior to setting the LVT LINT
registers which already clear LVT LINT0, and hence the troublesome
write can be avoided as the register is already cleared.
Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 782b48b7f7
master date: 2020-01-29 14:47:00 +0100
When passed a non-NULL pdev, the function does an owner check when it
finds an already existing context mapping. Bridges, however, don't get
passed through to guests, and hence their owner is always going to be
Dom0, leading to the assigment of all but one of the function of multi-
function PCI devices behind bridges to fail.
Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
master commit: a4d457fd59
master date: 2020-01-22 16:39:58 +0100
Due to AMD and Hygon being unable to selectively trap CR4 bit modifications
running 32-bit PV guest inside PV shim comes with significant performance
hit. Moreover, for SMEP in particular every time CR4.SMEP changes on context
switch to/from 32-bit PV guest, it gets trapped by L0 Xen which then
tries to perform global TLB invalidation for PV shim domain. This usually
results in eventual hang of a PV shim with at least several vCPUs.
Since the overall security risk is generally lower for shim Xen as it being
there more of a defense-in-depth mechanism, choose to disable SMEP/SMAP in
it by default on AMD and Hygon unless a user chose otherwise.
Signed-off-by: Igor Druzhinin <igor.druzhinin@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: b05ec9263e
master date: 2020-01-17 16:18:20 +0100
If ITSC is not available on CPU (e.g if running nested as PV shim)
then X86_FEATURE_NONSTOP_TSC is not advertised in certain cases, i.e.
all AMD and some old Intel processors. In which case TSC would need to
be restored on CPU from platform time by Xen upon exiting C-states.
As platform time might be behind the last TSC stamp recorded for the
current CPU, invariant of TSC stamp being always behind local TSC counter
is violated. This has an effect of get_s_time() going negative resulting
in eventual system hang or crash.
Fix this issue by updating local TSC stamp along with TSC counter write.
Signed-off-by: Igor Druzhinin <igor.druzhinin@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
master commit: bbf283f853
master date: 2020-01-17 16:11:20 +0100
FIFO event channels allow ports up to 2^17, so we need to use a wider
field in struct pirq. Move "masked" such that it may share the 8-byte
slot with struct arch_pirq on 64-bit arches, rather than leaving a
7-byte hole in all cases.
Take the opportunity and also add a comment regarding "arch" placement
within the structure.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Arm: fix build after 892b9dcebd
"IRQ: u16 is too narrow for an event channel number" introduced a use of
evetchn_port_t, but its typedef apparently surfaces indirectly here only
on x86.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: 892b9dcebd
master date: 2020-01-14 12:03:47 +0100
master commit: b4194711ff
master date: 2020-01-14 16:06:27 +0100
cpu_smpboot_free() removes the stubs for the cpu going offline, but it
isn't clearing the related percpu variables. This will result in
crashes when a stub page is released due to all related cpus gone
offline and one of those cpus going online later.
Fix that by clearing stubs.addr and stubs.mfn in order to allocate a
new stub page when needed, irrespective of whether the CPU gets parked
or removed.
Fixes: 2e6c8f182c ("x86: distinguish CPU offlining from CPU removal")
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Wei Liu <wl@xen.org>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Tested-by: Tao Xu <tao3.xu@intel.com>
master commit: 774901788c
master date: 2020-01-09 11:07:38 +0100
Some CPUs can speculate past an ERET instruction and potentially perform
speculative accesses to memory before processing the exception return.
Since the register state is often controlled by lower privilege level
at the point of an ERET, this could potentially be used as part of a
side-channel attack.
Newer CPUs may implement a new SB barrier instruction which acts
as an architected speculation barrier. For current CPUs, the sequence
DSB; ISB is known to prevent speculation.
The latter sequence is heavier than SB but it would never be executed
(this is speculation after all!).
Introduce a new macro 'sb' that could be used when a speculation barrier
is required. For now it is using dsb; isb but this could easily be
updated to cater SB in the future.
This is XSA-312.
Signed-off-by: Julien Grall <julien@xen.org>
Sometimes, on x86_64, decompression fails with the following
error:
Decompressing Linux...
Decoding failed
-- System halted
This condition is not needed for a 64bit kernel(from commit d5e7caf):
if( ... ||
(op + COPYLENGTH) > oend)
goto _output_error
macro LZ4_SECURE_COPY() tests op and does not copy any data
when op exceeds the value.
added by analogy to lz4_uncompress_unknownoutputsize(...)
Signed-off-by: Krzysztof Kolasa <kkolasa@winsoft.pl>
[Linux commit 99b7e93c95c78952724a9783de6c78def8fbfc3f]
The offending commit in our case is fcc17f96c2 ("LZ4 : fix the data
abort issue").
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: 5d90ff7954
master date: 2019-12-09 14:02:35 +0100
I clearly went too far there: While the LZ4_WILDCOPY() instances indeed
need prior guarding, LZ4_SECURECOPY() needs this only in the 32-bit case
(where it simply aliases LZ4_WILDCOPY()). "cpy" can validly point
(slightly) below "op" in these cases, due to
cpy = op + length - (STEPSIZE - 4);
where length can be as low as 0 and STEPSIZE is 8. However, instead of
removing the check via "#if !LZ4_ARCH64", refine it such that it would
also properly work in the 64-bit case, aborting decompression instead
of continuing on bogus input.
Reported-by: Mark Pryor <pryorm09@gmail.com>
Reported-by: Jeremi Piotrowski <jeremi.piotrowski@gmail.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Tested-by: Mark Pryor <pryorm09@gmail.com>
Tested-by: Jeremi Piotrowski <jeremi.piotrowski@gmail.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: 2d7572cdfa
master date: 2019-12-09 14:01:25 +0100
When PCID is not available Xen does a full tlbflush by toggling the
PGE bit in CR4. This is not necessary if PGE is not enabled, since a
flush can be performed by writing to CR3 in that case.
Change the code in do_tlb_flush to only toggle the PGE bit in CR4 if
it's already enabled, otherwise do the tlb flush by writing to CR3.
This is relevant when running virtualized, since hypervisors don't
usually trap accesses to CR3 when using hardware assisted paging, but
do trap accesses to CR4 specially on AMD hardware, which makes such
accesses much more expensive.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: b5087a31ef
master date: 2019-12-03 14:15:35 +0100
Linux commit fc5db58539b49351e76f19817ed1102bf7c712d0 says
"Some Coffee Lake platforms have a skewed HPET timer once the SoCs entered
PC10, which in consequence marks TSC as unstable because HPET is used as
watchdog clocksource for TSC."
Follow this for Xen as well. Looking at its patch context made me notice
they have a pre-existing quirk for Bay Trail as well. The comment there,
however, points at a Cherry Trail document. Looking at the datasheets of
both, there appear to be similar issues, so go beyond Linux'es coverage
and exclude both. Also key the disable on the PCI IDs of the actual
affected devices, rather than those of 00:00.0.
Apply the workarounds only when the use of HPET was not explicitly
requested on the command line and when use of (deep) C-states was not
disabled.
Adjust a few types in touched or nearby code at the same time.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: d5294a302c
master date: 2019-12-03 14:14:44 +0100
Two almost simultaneous mapping requests need to make sure that at the
completion of the earlier one IOMMU mappings (established explicitly
here in the PV case) have been put in place. Forever since the splitting
of the grant table lock a violation of this has been possible (using
simplified pin counts, as it doesn't matter whether we talk about read
or write mappings here):
initial state: act->pin = 0
vCPU A: progress the operation past the dropping of the locks after the
act->pin updates (act->pin = 1, old_pin = 0, act_pin = 1)
vCPU B: progress the operation past the dropping of the locks after the
act->pin updates (act->pin = 2, old_pin = 1, act_pin = 2)
vCPU B: (re-)acquire both gt locks, mapkind() returns 0, but both
iommu_legacy_map() invocations get skipped due to non-zero
old_pin
vCPU B: return to caller without IOMMU mapping
vCPU A: (re-)acquire both gt locks, mapkind() returns 0,
iommu_legacy_map() gets invoked
With the locks dropped intermediately, whether to invoke
iommu_legacy_map() must depend on only the return value of mapkind()
and of course the kind of mapping request being processed, just like
is already the case in unmap_common().
Also fix the style of the adjacent comment, and correct a nearby one
still referring to a prior name of what is now mapkind().
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: 921f1f4226
master date: 2019-12-03 14:13:40 +0100
During test, we found a crash on Xen with below trace.
(XEN) Xen call trace:
(XEN) [<ffff82d0802a065a>] R psr.c#l3_cdp_write_msr+0x1e/0x22
(XEN) [<ffff82d0802a0858>] F psr.c#do_write_psr_msrs+0x6d/0x109
(XEN) [<ffff82d08023e000>] F smp_call_function_interrupt+0x5a/0xac
(XEN) [<ffff82d0802a2b89>] F call_function_interrupt+0x20/0x34
(XEN) [<ffff82d080282c64>] F do_IRQ+0x175/0x6ae
(XEN) [<ffff82d08038b8ba>] F common_interrupt+0x10a/0x120
(XEN) [<ffff82d0802ec616>] F cpu_idle.c#acpi_idle_do_entry+0x9d/0xb1
(XEN) [<ffff82d0802ecc01>] F cpu_idle.c#acpi_processor_idle+0x41d/0x626
(XEN) [<ffff82d08027353b>] F domain.c#idle_loop+0xa5/0xa7
(XEN)
(XEN)
(XEN) ****************************************
(XEN) Panic on CPU 20:
(XEN) GENERAL PROTECTION FAULT
(XEN) [error_code=0000]
(XEN) ****************************************
The bug happens when CDP and MBA co-exist and MBA COS_MAX is bigger
than CDP COS_MAX. E.g. MBA has 8 COS registers but CDP only have 6.
When setting MBA throttling value for the 7th guest, the value array
would be:
+------------------+------------------+--------------+
| Data default val | Code default val | MBA throttle |
+------------------+------------------+--------------+
Then, COS id 7 will be selected for writting the values. We should
avoid writting CDP data/code valules to COS id 7 MSR because it
exceeds the CDP COS_MAX.
Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: 42c8cdc039
master date: 2019-12-02 15:15:18 +0000
This patch introduces a new iommu_op to facilitate a per-implementation
quarantine set up, and then further code for x86 implementations
(amd and vtd) to set up a read-only scratch page to serve as the source
for DMA reads whilst a device is assigned to dom_io. DMA writes will
continue to fault as before.
The reason for doing this is that some hardware may continue to re-try
DMA (despite FLR) in the event of an error, or even BME being cleared, and
will fail to deal with DMA read faults gracefully. Having a scratch page
mapped will allow pending DMA reads to complete and thus such buggy
hardware will eventually be quiesced.
NOTE: These modifications are restricted to x86 implementations only as
the buggy h/w I am aware of is only used with Xen in an x86
environment. ARM may require similar code but, since I am not
aware of the need, this patch does not modify any ARM implementation.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: ea38867831
master date: 2019-11-29 18:27:54 +0000
A guest will setup a shared page with the hypervisor for each vCPU via
XENPMU_init. The page will then get mapped in the hypervisor and only
released when XENPMU_finish is called.
This means that if the guest fails to invoke XENPMU_finish, e.g if it is
destroyed rather than cleanly shut down, the page will stay mapped in the
hypervisor. One of the consequences is the domain can never be fully
destroyed as a page reference is still held.
As Xen should never rely on the guest to correctly clean-up any
allocation in the hypervisor, we should also unmap such pages during the
domain destruction if there are any left.
We can re-use the same logic as in pvpmu_finish(). To avoid
duplication, move the logic in a new function that can also be called
from vpmu_destroy().
NOTE: - The call to vpmu_destroy() must also be moved from
arch_vcpu_destroy() into domain_relinquish_resources() such that
the reference on the mapped page does not prevent domain_destroy()
(which calls arch_vcpu_destroy()) from being called.
- Whilst it appears that vpmu_arch_destroy() is idempotent it is
by no means obvious. Hence make sure the VPMU_CONTEXT_ALLOCATED
flag is cleared at the end of vpmu_arch_destroy().
- This is not an XSA because vPMU is not security supported (see
XSA-163).
Signed-off-by: Julien Grall <jgrall@amazon.com>
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: be18e39d2f
master date: 2019-11-29 18:23:24 +0000
The TASK_SWITCH vmexit has fault semantics, and doesn't provide any NRIPs
assistance with instruction length. As a result, any instruction-induced task
switch has the outgoing task's %eip pointing at the instruction switch caused
the switch, rather than after it.
This causes callers of task gates to livelock (repeatedly execute the call/jmp
to enter the task), and any restartable task to become a nop after its first
use (the (re)entry state points at the iret used to exit the task).
32bit Windows in particular is known to use task gates for NMI handling, and
to use NMI IPIs.
In the task switch handler, distinguish instruction-induced from
interrupt/exception-induced task switches, and decode the instruction under
%rip to calculate its length.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 1d758bc6d1
master date: 2019-11-28 17:14:38 +0000
ICEBP isn't handled well by SVM.
The VMexit state for a #DB-vectored TASK_SWITCH has %rip pointing to the
appropriate instruction boundary (fault or trap, as appropriate), except for
an ICEBP-induced #DB TASK_SWITCH, where %rip points at the ICEBP instruction
rather than after it. As ICEBP isn't distinguished in the vectoring event
type, the state is ambiguous.
To add to the confusion, an ICEBP which occurs due to Introspection
intercepting the instruction, or from x86_emulate() will have %rip updated as
a consequence of partial emulation required to inject an ICEBP event in the
first place.
We could in principle spot the non-injected case in the TASK_SWITCH handler,
but this still results in complexity if the ICEBP instruction also has an
Instruction Breakpoint active on it (which genuinely has fault semantics).
Unconditionally intercept ICEBP. This does have NRIPs support as it is an
instruction intercept, which allows us to move %rip forwards appropriately
before the TASK_SWITCH intercept is hit. This makes #DB-vectored switches
have consistent behaviour however the ICEBP #DB came about, and avoids special
cases in the TASK_SWITCH intercept.
This in turn allows for the removal of the conditional
hvm_set_icebp_interception() logic used by the monitor subsystem, as ICEBP's
will now always be submitted for monitoring checks.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Alexandru Isaila <aisaila@bitdefender.com>
Reviewed-by: Petre Pircalabu <ppircalabu@bitdefender.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
master commit: e2585f8c2e
master date: 2019-11-28 17:14:38 +0000
The VT-x task switch handler adds inst_len to %rip before calling
hvm_task_switch(), which is problematic in two ways:
1) Early faults (i.e. ones delivered in the context of the old task) get
delivered with trap semantics, and break restartibility.
2) The addition isn't truncated to 32 bits. In the corner case of a task
switch instruction crossing the 4G->0 boundary taking an early fault (with
trap semantics), a VMEntry failure will occur due to %rip being out of
range.
Instead, pass the instruction length into hvm_task_switch() and write it into
the outgoing TSS only, leaving %rip in its original location.
For now, pass 0 on the SVM side. This highlights a separate preexisting bug
which will be addressed in the following patch.
While adjusting call sites, drop the unnecessary uint16_t cast.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
master commit: 943c74bc0e
master date: 2019-11-28 17:14:38 +0000
When using posted interrupts on Intel hardware it's possible that the
vCPU resumes execution with a stale local APIC IRR register because
depending on the interrupts to be injected vlapic_has_pending_irq
might not be called, and thus PIR won't be synced into IRR.
Fix this by making sure PIR is always synced to IRR in
hvm_vcpu_has_pending_irq regardless of what interrupts are pending.
Reported-by: Joe Jin <joe.jin@oracle.com>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Tested-by: Joe Jin <joe.jin@oracle.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
master commit: 56348df32b
master date: 2019-11-28 11:58:25 +0100
This hypercall can take a long time to finish because it attempts to
grab the `hostp2m' lock up to 1024 times. The accumulated wait for the
lock can take several seconds.
This can easily happen with a guest with 32 vcpus and plenty of RAM,
during localhost migration.
While the patch doesn't fix the problem with the lock contention and
the fact that the `hostp2m' lock is currently global (and not on a
single page), it is still an improvement to the hypercall. It will in
particular, down the road, allow dropping the arbitrary limit of 1024
entries per request.
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
master commit: 48599114d3
master date: 2019-11-26 14:16:09 +0100
Clang-3.5 from Debian Jessie fails with:
smpboot.c:829:29: error: statement expression not allowed at file scope
BUILD_BUG_ON(sizeof(this_cpu(tss_page)) != PAGE_SIZE);
^
/local/xen.git/xen/include/asm/percpu.h:14:7: note: expanded from macro
'this_cpu'
(*RELOC_HIDE(&per_cpu__##var, get_cpu_info()->per_cpu_offset))
^
/local/xen.git/xen/include/xen/compiler.h:98:3: note: expanded from macro
'RELOC_HIDE'
({ unsigned long __ptr; \
^
/local/xen.git/xen/include/xen/lib.h:26:53: note: expanded from macro
'BUILD_BUG_ON'
#define BUILD_BUG_ON(cond) ((void)BUILD_BUG_ON_ZERO(cond))
^
/local/xen.git/xen/include/xen/lib.h:25:57: note: expanded from macro
'BUILD_BUG_ON_ZERO'
#define BUILD_BUG_ON_ZERO(cond) sizeof(struct { int:-!!(cond); })
^
1 error generated.
/local/xen.git/xen/Rules.mk:202: recipe for target 'smpboot.o' failed
This is obviously a compiler bug because the BUILD_BUG_ON() is not at file
scope. However, it can be worked around by using a local variable.
Spotted by Gitlab CI.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Wei Liu <wl@xen.org>
master commit: 1722da6c0c
master date: 2019-08-14 12:04:20 +0100
Changeset ca2eee92df ("x86, hvm: Expose host core/HT topology to HVM
guests") attempted to "fake up" a topology which would induce guest
operating systems to not treat vcpus as sibling hyperthreads. This
involved actually reporting hyperthreading as available, but giving
vcpus every other ApicId; which in turn led to doubling the ApicIds
per core by bumping the ApicIdCoreSize by one. In particular, Ryzen
3xxx series processors, and reportedly EPYC "Rome" cpus -- have an
ApicIdCoreSize of 7; the "fake" topology increases this to 8.
Unfortunately, Windows running on modern AMD hardware -- including
Ryzen 3xxx series processors, and reportedly EPYC "Rome" cpus --
doesn't seem to cope with this value being higher than 7. (Linux
guests have so far continued to cope.)
A "proper" fix is complicated and it's too late to fix it either for
4.13, or to backport to supported branches. As a short-term fix,
limit this value to 7.
This does mean that a Linux guest, booted on such a system without
this change, and then migrating to a system with this change, with
more than 64 vcpus, would see an apparent topology change. This is a
low enough risk in practice that enabling this limit unilaterally, to
allow other guests to boot without manual intervention, is worth it.
Reported-by: Steven Haigh <netwiz@crc.id.au>
Reported-by: Andreas Kinzler <hfp@posteo.de>
Signed-off-by: George Dunlap <george.dunlap@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
master commit: 8c79c129a6
master date: 2019-11-26 10:33:52 +0000
update_paging_mode() has multiple bugs:
1) Booting with iommu=debug will cause it to inform you that that it called
without the pdev_list lock held.
2) When growing by more than a single level, it leaks the newly allocated
table(s) in the case of a further error.
Furthermore, the choice of default level for a domain has issues:
1) All HVM guests grow from 2 to 3 levels during construction because of the
position of the VRAM just below the 4G boundary, so defaulting to 2 is a
waste of effort.
2) The limit for PV guests doesn't take memory hotplug into account, and
isn't dynamic at runtime like HVM guests. This means that a PV guest may
get RAM which it can't map in the IOMMU.
The dynamic height is a property unique to AMD, and adds a substantial
quantity of complexity for what is a marginal performance improvement. Remove
the complexity by removing the dynamic height.
PV guests now get 3 or 4 levels based on any hotplug regions in the host.
This only makes a difference for hardware which previously had all RAM below
the 512G boundary, and a hotplug region above.
HVM guests now get 4 levels (which will be sufficient until 256TB guests
become a thing), because we don't currently have the information to know when
3 would be safe to use.
The overhead of this extra level is not expected to be noticeable. It costs
one page (4k) per domain, and one extra IO-TLB paging structure cache entry
which is very hot and less likely to be evicted.
This is XSA-311.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
master commit: b4f042236a
master date: 2019-12-11 14:55:32 +0100
The PGT_partial bit in page->type_info holds both a type count and a
general ref count. During domain tear-down, when free_page_type()
returns -ERESTART, relinquish_memory() correctly handles the general
ref count, but fails to grab an extra type count when setting
PGT_partial. When this bit is eventually cleared, type_count underflows
and triggers the following BUG in page_alloc.c:free_domheap_pages():
BUG_ON((pg[i].u.inuse.type_info & PGT_count_mask) != 0);
As far as we can tell, this page underflow cannot be exploited any any
other way: The page can't be used as a pagetable by the dying domain
because it's dying; it can't be used as a pagetable by any other
domain since it belongs to the dying domain; and ownership can't
transfer to any other domain without hitting the BUG_ON() in
free_domheap_pages().
(steal_page() won't work on a page in this state, since it requires
PGC_allocated to be set, and PGC_allocated will already have been
cleared.)
Fix this by grabbing an extra type ref if setting PGT_partial in
relinquish_memory.
This is part of XSA-310.
Signed-off-by: George Dunlap <george.dunlap@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
master commit: 66bdc16aee
master date: 2019-12-11 14:55:08 +0100
When validating or de-validating pages (in alloc_lN_table and
free_lN_table respectively), the `partial_flags` local variable is
used to keep track of whether the "current" PTE started the entire
operation in a "may be partial" state.
One of the patches in XSA-299 addressed the fact that it is possible
for a previously-partially-validated entry to subsequently be found to
have invalid entries (indicated by returning -EINVAL); in which case
page->partial_flags needs to be set to indicate that the current PTE
may have the partial bit set (and thus _put_page_type() should be
called with PTF_partial_set).
Unfortunately, the patches in XSA-299 assumed that once
put_page_from_lNe() returned -ERESTART on a page, it was not possible
for it to return -EINTR. This turns out to be true for
alloc_lN_table() and free_lN_table, but not for _get_page_type() and
_put_page_type(): both can return -EINTR when called on pages with
PGT_partial set. In these cases, the pages PGT_partial will still be
set; failing to set partial_flags appropriately may allow an attacker
to do a privilege escalation similar to those described in XSA-299.
Fix this by always copying the local partial_flags variable into
page->partial_flags when exiting early.
NB that on the "get" side, no adjustment to nr_validated_entries is
needed: whether pte[i] is partially validated or entirely
un-validated, we want nr_validated_entries = i. On the "put" side,
however, we need to adjust nr_validated_entries appropriately: if
pte[i] is entirely validated, we want nr_validated_entries = i + 1; if
pte[i] is partially validated, we want nr_validated_entries = i.
This is part of XSA-310.
Signed-off-by: George Dunlap <george.dunlap@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 4e70f4476c
master date: 2019-12-11 14:54:43 +0100
Changeset 6c4efc1eba ("x86/mm: Don't drop a type ref unless you held a
ref to begin with"), part of XSA-299, changed the calling discipline
of put_page_type() such that if put_page_type() returned -ERESTART
(indicating a partially de-validated page), subsequent calls to
put_page_type() must be called with PTF_partial_set. If called on a
partially de-validated page but without PTF_partial_set, Xen will
BUG(), because to do otherwise would risk opening up the kind of
privilege escalation bug described in XSA-299.
One place this was missed was in vcpu_destroy_pagetables().
put_page_and_type_preemptible() is called, but on -ERESTART, the
entire operation is simply restarted, causing put_page_type() to be
called on a partially de-validated page without PTF_partial_set. The
result was that if such an operation were interrupted, Xen would hit a
BUG().
Fix this by having vcpu_destroy_pagetables() consistently pass off
interrupted de-validations to put_old_page_type():
- Unconditionally clear references to the page, even if
put_page_and_type failed
- Set old_guest_table and old_guest_table_partial appropriately
While here, do some refactoring:
- Move clearing of arch.cr3 to the top of the function
- Now that clearing is unconditional, move the unmap to the same
conditional as the l4tab mapping. This also allows us to reduce
the scope of the l4tab variable.
- Avoid code duplication by looping to drop references on
guest_table_user
This is part of XSA-310.
Reported-by: Sarah Newman <srn@prgmr.com>
Signed-off-by: George Dunlap <george.dunlap@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: ececa12b2c
master date: 2019-12-11 14:54:13 +0100
"Linear pagetables" is a technique which involves either pointing a
pagetable at itself, or to another pagetable the same or higher level.
Xen has limited support for linear pagetables: A page may either point
to itself, or point to another page of the same level (i.e., L2 to L2,
L3 to L3, and so on).
XSA-240 introduced an additional restriction that limited the "depth"
of such chains by allowing pages to either *point to* other pages of
the same level, or *be pointed to* by other pages of the same level,
but not both. To implement this, we keep track of the number of
outstanding times a page points to or is pointed to another page
table, to prevent both from happening at the same time.
Unfortunately, the original commit introducing this reset this count
when resuming validation of a partially-validated pagetable, dropping
some "linear_pt_entry" counts.
On debug builds on systems where guests used this feature, this might
lead to crashes that look like this:
Assertion 'oc > 0' failed at mm.c:874
Worse, if an attacker could engineer such a situation to occur, they
might be able to make loops or other abitrary chains of linear
pagetables, leading to the denial-of-service situation outlined in
XSA-240.
This is XSA-309.
Reported-by: Manuel Bouyer <bouyer@antioche.eu.org>
Signed-off-by: George Dunlap <george.dunlap@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 7473efd12f
master date: 2019-12-11 14:10:27 +0100
See patch comment for technical details.
Concerning the timeline, this was first discovered in the aftermath of
XSA-156 which caused #DB to be intercepted unconditionally, but only in
its SingleStep + STI form which is restricted to privileged software.
After working with Intel and identifying the problematic vmentry check,
this workaround was suggested, and the patch was posted in an RFC
series. Outstanding work for that series (not breaking Introspection)
is still pending, and this fix from it (which wouldn't have been good
enough in its original form) wasn't committed.
A vmentry failure was reported to xen-devel, and debugging identified
this bug in its SingleStep + MovSS form by way of INT1, which does not
involve the use of any privileged instructions, and proving this to be a
security issue.
This is XSA-308
Reported-by: Håkon Alstadheim <hakon@alstadheim.priv.no>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Kevin Tian <kevin.tian@intel.com>
master commit: 1d3eb82598
master date: 2019-12-11 14:09:30 +0100
These functions getting used with the 2nd and 3rd arguments being equal
wasn't well defined: Arm64 reliably returns the value of the 2nd
argument in this case, while on x86 for bitmaps up to 64 bits wide the
return value was undefined (due to the undefined behavior of a shift of
a value by the number of bits it's wide) when the incoming value was 64.
On Arm32 an actual out of bounds access would happen when the
size/offset value is a multiple of 32; if this access doesn't fault, the
return value would have been sufficiently correct afaict.
Make the functions consistently tolerate the last two arguments being
equal (and in fact the 3rd argument being greater or equal to the 2nd),
in favor of finding and fixing all the use sites that violate the
original more strict assumption.
This is XSA-307.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Julien Grall <julien@xen.org>
master commit: 7442006b9f
master date: 2019-12-11 14:06:18 +0100
Dario Faggioli
Andrew Cooper
Jan Beulich
Igor Druzhinin
David Woodhouse
Julien Grall
Roger Pau Monné
Juergen Gross
Julien Grall
Krzysztof Kolasa
Yi Sun
Paul Durrant
Anthony PERARD
George Dunlap