TSA affects AMD Fam19h CPUs (Zen3 and 4 microarchitectures).
Three new CPUID bits have been defined. Two (TSA_SQ_NO and TSA_L1_NO)
indicate that the system is unaffected, and must be synthesised by Xen on
unaffected parts to date.
A third new bit indicates that VERW now has a flushing side effect. Xen must
synthesise this bit on affected systems based on microcode version. As with
other VERW-based flushing features, VERW_CLEAR needs OR-ing across a resource
pool, and guests which have seen it can safely migrate in.
This is part of XSA-471 / CVE-2024-36350 / CVE-2024-36357.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 578b34adb1)
Xen 4.18 doesn't automatically generate feature names like Xen 4.19 does, and
these hunks were missed on prior security fixes.
Fixes: 8bced9a15c ("x86/spec-ctrl: Support for SRSO_U/S_NO and SRSO_MSR_FIX")
Fixes: f132c82fa6 ("x86/spec-ctrl: Synthesise ITS_NO to guests on unaffected hardware")
Fixes: dba0556612 ("x86/spec-ctrl: Support Intel's new PB-OPT")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
[For 4.17, PB-OPT wasn't backported]
(cherry picked from commit cd46db24e5)
Right now, Xen returns -ENOENT for both "the provided blob isn't correct for
this CPU", and "the blob isn't newer than what's loaded".
This in turn causes xen-ucode to exit with an error, when "nothing to do" is
more commonly a success condition.
Handle EEXIST specially and exit cleanly.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
master commit: 648db37a15
master date: 2024-05-09 18:19:49 +0100
RFDS affects Atom cores, also branded E-cores, between the Goldmont and
Gracemont microarchitectures. This includes Alder Lake and Raptor Lake hybrid
clien systems which have a mix of Gracemont and other types of cores.
Two new bits have been defined; RFDS_CLEAR to indicate VERW has more side
effets, and RFDS_NO to incidate that the system is unaffected. Plenty of
unaffected CPUs won't be getting RFDS_NO retrofitted in microcode, so we
synthesise it. Alder Lake and Raptor Lake Xeon-E's are unaffected due to
their platform configuration, and we must use the Hybrid CPUID bit to
distinguish them from their non-Xeon counterparts.
Like MD_CLEAR and FB_CLEAR, RFDS_CLEAR needs OR-ing across a resource pool, so
set it in the max policies and reflect the host setting in default.
This is part of XSA-452 / CVE-2023-28746.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit fb5b6f6744)
This is an AMD feature to reduce the IBRS handling overhead. Once enabled,
processes running at CPL=0 are automatically IBRS-protected even if
SPEC_CTRL.IBRS is not set. Furthermore, the RAS/RSB is cleared on VMEXIT.
The feature is exposed in CPUID and toggled in EFER.
Signed-off-by: Alejandro Vallejo <alejandro.vallejo@cloud.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: 8347d6bb29
master date: 2023-05-30 18:24:07 +0100
GDS_CTRL is introduced by the August 2023 microcode. GDS_NO is for current
and future processors not susceptible to GDS.
This is part of XSA-435 / CVE-2022-40982
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 9f585f59d9)
AMD have specified new CPUID bits relating to SRSO.
* SRSO_NO indicates that hardware is no longer vulnerable to SRSO.
* IBPB_BRTYPE indicates that IBPB flushes branch type information too.
* SBPB indicates support for a relaxed form of IBPB that does not flush
branch type information.
Current CPUs (Zen4 and older) are not expected to enumerate these bits.
Native software is expected to synthesise them for guests using model and
microcode revision checks.
Two are just status bits, and SBPB is trivial to support for guests by
tweaking the reserved bit calculation in guest_wrmsr() and feature
dependencies. Expose all by default to guests, so they start showing up when
Xen synthesises them.
While adding feature dependenies for IBPB, fix up an overlooked issue from
XSA-422. It's inappropriate to advertise that IBPB flushes RET predictions if
IBPB is unavailable itself.
This is part of XSA-434 / CVE-2023-20569
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 2280b0ee2a)
Seed the default visibility from the dom0 special case, which for the most
part just exposes the *_NO bits. EIBRS is the one non-*_NO bit, which is
"just" a status bit to the guest indicating a change in implemention of IBRS
which is already fully supported.
Insert a block dependency from the ARCH_CAPS CPUID bit to the entire content
of the MSR. This is because MSRs have no structure information similar to
CPUID, and used by x86_cpu_policy_clear_out_of_range_leaves(), in order to
bulk-clear inaccessable words.
The overall CPUID bit is still max-only, so all of MSR_ARCH_CAPS is hidden in
the default policies.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit ce8c930851)
Bits through 24 are already defined, meaning that we're not far off needing
the second word. Put both in right away.
As both halves are present now, the arch_caps field is full width. Adjust the
unit test, which notices.
The bool bitfield names in the arch_caps union are unused, and somewhat out of
date. They'll shortly be automatically generated.
Add CPUID and MSR prefixes to the ./xen-cpuid verbose output, now that there
are a mix of the two.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit d9fe459ffa)
Featuresets are supposed to be disappearing when the CPU policy infrastructure
is complete, but that has taken longer than expected, and isn't going to be
complete imminently either.
In the meantime, Xen does have proper default/max featuresets, and xen-cpuid
can even get them via the XEN_SYSCTL_cpu_policy_* interface, but only knows
now to render them nicely via the featureset interface.
Differences between default and max are a frequent source of errors,
frequently too in secret leading up to an embargo, so extend the featureset
sysctl to allow xen-cpuid to render them all nicely.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Christian Lindig <christian.lindig@cloud.com>
(cherry picked from commit 433d012c6c)
struct fsinfo is the vestigial remnant of an older internal design which
didn't survive very long.
Simplify things by inlining get_featureset() and having a single memory
allocation that gets reused. This in turn changes featuresets[] to be a
simple list of names, so rename it to fs_names[].
No functional change.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit ec3474e1dd)
This was an oversight when adding the Xen parts.
Fixes: cea9ae0622 ("x86/spec-ctrl: Enumeration for new Intel BHI controls")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 9276e832ae
master date: 2023-03-13 11:26:26 +0000
Refer to Intel SDM Rev 70 (Dec 2022), Vol3 17.2.3 "Supervisor Shadow Stack
Token".
Architecturally, an event delivery which starts in CPL<3 and switches shadow
stack will first validate the Supervisor Shadow Stack Token (setting the busy
bit), then pushes CS/LIP/SSP. One example of this is an NMI interrupting Xen.
Some CPUs suffer from an issue called fracturing, whereby a fault/vmexit/etc
between setting the busy bit and completing the event injection renders the
action non-restartable, because when it comes time to restart, the busy bit is
found to be already set.
This is far more easily encountered under virt, yet it is not the fault of the
hypervisor, nor the fault of the guest kernel. The fault lies somewhere
between the architectural specification, and the uarch behaviour.
Intel have allocated CPUID.7[1].ecx[18] CET_SSS to enumerate that supervisor
shadow stacks are safe to use. Because of how Xen lays out its shadow stacks,
fracturing is not expected to be a problem on native.
Detect this case on boot and default to not using shstk if virtualised.
Specifying `cet=shstk` on the command line will override this heuristic and
enable shadow stacks irrespective.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 01e7477d1b
master date: 2023-02-09 18:26:17 +0000
We don't actually need ecx yet, but adding it in now will reduce the amount to
which leaf 7 is out of order in a featureset.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: b4a23bf629
master date: 2023-02-09 18:26:17 +0000
The IBPB_RET bit indicates that the CPU's implementation of MSR_PRED_CMD.IBPB
does flush the RSB/RAS too.
This is part of XSA-422 / CVE-2022-23824.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
BTC_NO indicates that hardware is not succeptable to Branch Type Confusion.
Zen3 CPUs don't suffer BTC.
This is part of XSA-407.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Expose the MCDT_NO CPUID flag to guests if available. The bit signals
that the CPU does not exhibit MCDT behavior, and as such can be
exposed without requiring any additional work.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
The Feb 2022 microcode from Intel retrofits AMD's MSR_SPEC_CTRL.PSFD interface
to Sunny Cove (IceLake) and later cores.
Update the MSR_SPEC_CTRL emulation, and expose it to guests.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
While in principle it would be nice to keep leaf 7 in order, that would
involve having an extra 5 words of zeros in a featureset.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
As of SDM revision 076 there is a CPUID bit for this functionality. Use
it to amend the existing model-based logic.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Do this before adding any more stuff to xg_cpuid_x86.c.
The placement in xenctrl.h is wrong, as they are implemented by the
xenguest library. Note that xg_cpuid_x86.c needs to include
xg_private.h, and in turn also fix xg_private.h to include
xc_bitops.h. The bitops definition of BITS_PER_LONG needs to be
changed to not be an expression, so that xxhash.h can use it in a
preprocessor if directive.
As a result also modify xen-cpuid to include xenguest.h.
Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Anthony PERARD <anthony.perard@citrix.com>
The 64-bit form forces %ecx to 0 while the 32-bit one so far didn't - it
only ended up that way when "pv_context" is zero. While presently no
leaf queried by callers has separate subleaves, let's avoid chancing it.
While there
- replace references to operands by number,
- relax constraints where possible,
- limit PUSH/POP to just the registers not also used as input,
all where applicable also for the 64-bit variant.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
The first thing XEN_SYSCTL_physinfo does is zero op->u.physinfo.
Do not copy-in. It's pointless, and most callers don't initialise their
xc_physinfo_t buffer to begin with. Remove the redundant zeroing from the
remaining callers.
Spotted by Coverity.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Wei Chen <Wei.Chen@arm.com>
Acked-by: Anthony PERARD <anthony.perard@citrix.com>
There's no point producing a long chain of zeroes when the previously
calculated total value was zero. To guard against mistakenly skipping
non-zero individual fields, widen "sum" to "unsigned long long".
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Anthony PERARD <anthony.perard@citrix.com>
This table must not have got updated in quite a while; tmem_op for
example has managed to not only appear since then, but also disappear
again (adding a name for it nevertheless, to make more obvious that
something strange is going on if the slot would ever have a non-zero
value).
Also resolve arch_0 and arch_1 to more meaningful names on x86.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Add missing "xen-detect" rule. It only works without it because we
still have make's built-ins rules and variables, but fix this to not
have to rely on them.
Rename $(TARGETS_BUILD) to $(TARGETS).
Remove the unused "build" target.
Also, they are no more "build-only" targets, remove the extra code.
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
This avoid the need to create the symbolic link "include/asm".
Whenever a comment refer to an "asm" headers, this patch avoid
spelling the arch when not needed to avoid some code churn.
One unrelated change is to sort entries in MAINTAINERS for "INTEL(R)
VT FOR X86 (VT-X)"
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Paul Durrant <paul@xen.org>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Julien Grall <jgrall@amazon.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
TSXLDTRK lives in CPUID leaf 7[0].edx, not 7[0].ecx.
Bit 16 in ecx is LA57.
Fixes: a6d1b55847 ("x86emul: support X{SUS,RES}LDTRK")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Xen already collects CPUID.0x80000007.edx by default, meaning that we can
refer to per-cpu data directly. This also avoids the need IPI the onlining
CPU to identify whether Core Performance Boost is available.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
There is a step change in speculation protections between the Zen1 and Zen2
microarchitectures.
Zen1 and older have no special support. Control bits in non-architectural
MSRs are used to make lfence be dispatch-serialising (Spectre v1), and to
disable Memory Disambiguation (Speculative Store Bypass). IBPB was
retrofitted in a microcode update, and software methods are required for
Spectre v2 protections.
Because the bit controlling Memory Disambiguation is model specific,
hypervisors are expected to expose a MSR_VIRT_SPEC_CTRL interface which
abstracts the model specific details.
Zen2 and later implement the MSR_SPEC_CTRL interface in hardware, and
virtualise the interface for HVM guests to use. A number of hint bits are
specified too to help guide OS software to the most efficient mitigation
strategy.
Zen3 introduced a new feature, Predictive Store Forwarding, along with a
control to disable it in sensitive code.
Add CPUID and VMCB details for all the new functionality.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
AMD Zen3 adds the NullSelectorClearsBase bit to indicate that loading
a NULL segment selector zeroes the base and limit fields, as well as
just attributes.
Expose bit to all guests.
Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Jane Malalane <jane.malalane@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
mce-test has a test suite, but it depends on xend, needs to run in-tree, and
requires manual setup of at least one guest, and manual parameters to pass
into cases. Drop the test infrasturcture.
Move the one useful remaining item, xen-mceinj, into misc/, fixing some minor
style issues as it goes.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
The June 2021 microcode is formally de-featuring TSX on the older Skylake
client CPUs. The workaround from the March 2019 microcode is being dropped,
and replaced with additions to MSR_TSX_FORCE_ABORT to hide the HLE/RTM CPUID
bits.
With this microcode in place, TSX is disabled by default on these CPUs.
Backwards compatibility is provided in the same way as for TAA - RTM force
aborts, rather than suffering #UD, and the CPUID bits can be hidden to recover
performance.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
literal strings are not meant to be modified. So we should use const
char * rather than char * when we we to store a pointer to them.
Signed-off-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Wei Liu <wl@xen.org>
It is bad form in C, perhaps best demonstrated by trying to read
xc_cpu_policy_destroy(), and causes const qualification to have
less-than-obvious behaviour (the hidden pointer becomes const, not the thing
it points at).
xc_cpu_policy_set_domain() needs to drop its (now normal) const qualification,
as the policy object is modified by the serialisation operation.
This also shows up a problem with the x86_cpu_policies_are_compatible(), where
the intermediate pointers are non-const.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
With the introduction of xc_cpu_policy_get_{system,domain} and
xc_cpu_policy_serialise the current users of
xc_get_{system,domain}_cpu_policy can be switched to the new
interface.
Note that xc_get_{system,domain}_cpu_policy is removed from the public
interface and the functions are made static, since there are still
internal consumers in xg_cpuid_x86.c
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Preparatory change to introduce a new set of xc_cpu_policy_* functions
that will replace the current CPUID/MSR helpers.
No functional change intended.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
AMD Milan (Zen3) CPUs have an LFENCE Always Serialising CPUID bit in
leaf 80000021.eax. Previous AMD versions used to have a user settable
bit in DE_CFG MSR to select whether LFENCE was dispatch serialising,
which Xen always attempts to set. The forcefully always on setting is
due to the addition of SEV-SNP so that a VMM cannot break the
confidentiality of a guest.
In order to support this new CPUID bit move the LFENCE_DISPATCH
synthetic CPUID bit to map the hardware bit (leaving a hole in the
synthetic range) and either rely on the bit already being set by the
native CPUID output, or attempt to fake it in Xen by modifying the
DE_CFG MSR. This requires adding one more entry to the featureset to
support leaf 80000021.eax.
The bit is always exposed to guests by default even if the underlying
hardware doesn't support leaf 80000021. Note that Xen doesn't allow
guests to change the DE_CFG value, so once set by Xen LFENCE will always
be serialising.
Note that the access to DE_CFG by guests is left as-is: reads will
unconditionally return LFENCE_SERIALISE bit set, while writes are
silently dropped.
Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
[Always expose to guests by default]
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Like ERMS this can always be exposed to guests, but I guess once we
introduce full validation we want to make sure we don't reject incoming
policies with any of these set when in the raw/host policies they're
clear.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
While part of the original AMD64 spec, Long Mode Segment Limit was a feature
not picked up by Intel, and therefore didn't see much adoption in software.
AMD have finally dropped the feature from hardware, and allocated a CPUID bit
to indicate its absence.
Xen has never supported the feature for guests, even when running on capable
hardware, so advertise the feature's absence unilaterally.
There is nothing specifically wrong with exposing this bit to PV guests, but
the PV ABI doesn't include a working concept of MSR_EFER in the first place,
so exposing it to PV guests would be out-of-place.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
The expected behavior while using xen-vmtrace is to get a clean start, even if
the tool was used previously on the same VM.
Signed-off-by: Tamas K Lengyel <tamas@tklengyel.com>
Release-Acked-by: Ian Jackson <iwj@xenproject.org>
Reviewed-by: Ian Jackson <iwj@xenproject.org>
Add CPUID/MSR enumeration details for Processor Trace. For now, we will only
support its use inside VMX operation. Fill in the vmtrace_available boolean
to activate the newly introduced common infrastructure for allocating trace
buffers.
For now, Processor Trace is going to be operated in Single Output mode behind
the guests back. Add the MSRs to struct vcpu_msrs, and set up the buffer
limit in vmx_init_ipt() as it is fixed for the lifetime of the domain.
Context switch the most of the MSRs in and out of vCPU context, but the main
control register needs to reside in the MSR load/save lists. Explicitly pull
the msrs pointer out into a local variable, because the optimiser cannot keep
it live across the memory clobbers in the MSR accesses.
Signed-off-by: Michał Leszczyński <michal.leszczynski@cert.pl>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Release-Acked-by: Ian Jackson <iwj@xenproject.org>
memshrtool is a tool for a human to use, rather than a test. Move it into
misc/ as a more appropriate location to live. Also rename it to
xen-memshare
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Andrew Cooper
Alejandro Vallejo
Anthony PERARD
Jan Beulich
Roger Pau Monné
Jane Malalane
Tamas K Lengyel
Julien Grall
Michał Leszczyński