and use them everywhere instead of ad-hoc family/model checks. Drop an
ancient AMD errata checking facility as a result
- Fix a fragile initcall ordering in intel_epb
- Do not issue the MFENCE+LFENCE barrier for the TSC deadline and X2APIC
MSRs on AMD as it is not needed there
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Merge tag 'x86_cpu_for_v6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 cpu feature updates from Borislav Petkov:
- Add synthetic X86_FEATURE flags for the different AMD Zen generations
and use them everywhere instead of ad-hoc family/model checks. Drop
an ancient AMD errata checking facility as a result
- Fix a fragile initcall ordering in intel_epb
- Do not issue the MFENCE+LFENCE barrier for the TSC deadline and
X2APIC MSRs on AMD as it is not needed there
* tag 'x86_cpu_for_v6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/CPU/AMD: Add X86_FEATURE_ZEN1
x86/CPU/AMD: Drop now unused CPU erratum checking function
x86/CPU/AMD: Get rid of amd_erratum_1485[]
x86/CPU/AMD: Get rid of amd_erratum_400[]
x86/CPU/AMD: Get rid of amd_erratum_383[]
x86/CPU/AMD: Get rid of amd_erratum_1054[]
x86/CPU/AMD: Move the DIV0 bug detection to the Zen1 init function
x86/CPU/AMD: Move Zenbleed check to the Zen2 init function
x86/CPU/AMD: Rename init_amd_zn() to init_amd_zen_common()
x86/CPU/AMD: Call the spectral chicken in the Zen2 init function
x86/CPU/AMD: Move erratum 1076 fix into the Zen1 init function
x86/CPU/AMD: Move the Zen3 BTC_NO detection to the Zen3 init function
x86/CPU/AMD: Carve out the erratum 1386 fix
x86/CPU/AMD: Add ZenX generations flags
x86/cpu/intel_epb: Don't rely on link order
x86/barrier: Do not serialize MSR accesses on AMD
Add a synthetic feature flag specifically for first generation Zen
machines. There's need to have a generic flag for all Zen generations so
make X86_FEATURE_ZEN be that flag.
Fixes: 30fa92832f ("x86/CPU/AMD: Add ZenX generations flags")
Suggested-by: Brian Gerst <brgerst@gmail.com>
Suggested-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/dc3835e3-0731-4230-bbb9-336bbe3d042b@amd.com
Commit in Fixes added an AMD-specific microcode callback. However, it
didn't check the CPU vendor the kernel runs on explicitly.
The only reason the Zenbleed check in it didn't run on other x86 vendors
hardware was pure coincidental luck:
if (!cpu_has_amd_erratum(c, amd_zenbleed))
return;
gives true on other vendors because they don't have those families and
models.
However, with the removal of the cpu_has_amd_erratum() in
05f5f73936 ("x86/CPU/AMD: Drop now unused CPU erratum checking function")
that coincidental condition is gone, leading to the zenbleed check
getting executed on other vendors too.
Add the explicit vendor check for the whole callback as it should've
been done in the first place.
Fixes: 522b1d6921 ("x86/cpu/amd: Add a Zenbleed fix")
Cc: <stable@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20231201184226.16749-1-bp@alien8.de
Setting X86_BUG_AMD_E400 in init_amd() is early enough.
No functional changes.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Link: http://lore.kernel.org/r/20231120104152.13740-12-bp@alien8.de
Set it in init_amd_gh() unconditionally as that is the F10h init
function.
No functional changes.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Link: http://lore.kernel.org/r/20231120104152.13740-11-bp@alien8.de
Add X86_FEATURE flags for each Zen generation. They should be used from
now on instead of checking f/m/s.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lore.kernel.org/r/20231120104152.13740-2-bp@alien8.de
AMD does not have the requirement for a synchronization barrier when
acccessing a certain group of MSRs. Do not incur that unnecessary
penalty there.
There will be a CPUID bit which explicitly states that a MFENCE is not
needed. Once that bit is added to the APM, this will be extended with
it.
While at it, move to processor.h to avoid include hell. Untangling that
file properly is a matter for another day.
Some notes on the performance aspect of why this is relevant, courtesy
of Kishon VijayAbraham <Kishon.VijayAbraham@amd.com>:
On a AMD Zen4 system with 96 cores, a modified ipi-bench[1] on a VM
shows x2AVIC IPI rate is 3% to 4% lower than AVIC IPI rate. The
ipi-bench is modified so that the IPIs are sent between two vCPUs in the
same CCX. This also requires to pin the vCPU to a physical core to
prevent any latencies. This simulates the use case of pinning vCPUs to
the thread of a single CCX to avoid interrupt IPI latency.
In order to avoid run-to-run variance (for both x2AVIC and AVIC), the
below configurations are done:
1) Disable Power States in BIOS (to prevent the system from going to
lower power state)
2) Run the system at fixed frequency 2500MHz (to prevent the system
from increasing the frequency when the load is more)
With the above configuration:
*) Performance measured using ipi-bench for AVIC:
Average Latency: 1124.98ns [Time to send IPI from one vCPU to another vCPU]
Cumulative throughput: 42.6759M/s [Total number of IPIs sent in a second from
48 vCPUs simultaneously]
*) Performance measured using ipi-bench for x2AVIC:
Average Latency: 1172.42ns [Time to send IPI from one vCPU to another vCPU]
Cumulative throughput: 40.9432M/s [Total number of IPIs sent in a second from
48 vCPUs simultaneously]
From above, x2AVIC latency is ~4% more than AVIC. However, the expectation is
x2AVIC performance to be better or equivalent to AVIC. Upon analyzing
the perf captures, it is observed significant time is spent in
weak_wrmsr_fence() invoked by x2apic_send_IPI().
With the fix to skip weak_wrmsr_fence()
*) Performance measured using ipi-bench for x2AVIC:
Average Latency: 1117.44ns [Time to send IPI from one vCPU to another vCPU]
Cumulative throughput: 42.9608M/s [Total number of IPIs sent in a second from
48 vCPUs simultaneously]
Comparing the performance of x2AVIC with and without the fix, it can be seen
the performance improves by ~4%.
Performance captured using an unmodified ipi-bench using the 'mesh-ipi' option
with and without weak_wrmsr_fence() on a Zen4 system also showed significant
performance improvement without weak_wrmsr_fence(). The 'mesh-ipi' option ignores
CCX or CCD and just picks random vCPU.
Average throughput (10 iterations) with weak_wrmsr_fence(),
Cumulative throughput: 4933374 IPI/s
Average throughput (10 iterations) without weak_wrmsr_fence(),
Cumulative throughput: 6355156 IPI/s
[1] https://github.com/bytedance/kvm-utils/tree/master/microbenchmark/ipi-bench
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230622095212.20940-1-bp@alien8.de
- Limit the hardcoded topology quirk for Hygon CPUs to those which have a
model ID less than 4. The newer models have the topology CPUID leaf 0xB
correctly implemented and are not affected.
- Make SMT control more robust against enumeration failures
SMT control was added to allow controlling SMT at boottime or
runtime. The primary purpose was to provide a simple mechanism to
disable SMT in the light of speculation attack vectors.
It turned out that the code is sensible to enumeration failures and
worked only by chance for XEN/PV. XEN/PV has no real APIC enumeration
which means the primary thread mask is not set up correctly. By chance
a XEN/PV boot ends up with smp_num_siblings == 2, which makes the
hotplug control stay at its default value "enabled". So the mask is
never evaluated.
The ongoing rework of the topology evaluation caused XEN/PV to end up
with smp_num_siblings == 1, which sets the SMT control to "not
supported" and the empty primary thread mask causes the hotplug core to
deny the bringup of the APS.
Make the decision logic more robust and take 'not supported' and 'not
implemented' into account for the decision whether a CPU should be
booted or not.
- Fake primary thread mask for XEN/PV
Pretend that all XEN/PV vCPUs are primary threads, which makes the
usage of the primary thread mask valid on XEN/PV. That is consistent
with because all of the topology information on XEN/PV is fake or even
non-existent.
- Encapsulate topology information in cpuinfo_x86
Move the randomly scattered topology data into a separate data
structure for readability and as a preparatory step for the topology
evaluation overhaul.
- Consolidate APIC ID data type to u32
It's fixed width hardware data and not randomly u16, int, unsigned long
or whatever developers decided to use.
- Cure the abuse of cpuinfo for persisting logical IDs.
Per CPU cpuinfo is used to persist the logical package and die
IDs. That's really not the right place simply because cpuinfo is
subject to be reinitialized when a CPU goes through an offline/online
cycle.
Use separate per CPU data for the persisting to enable the further
topology management rework. It will be removed once the new topology
management is in place.
- Provide a debug interface for inspecting topology information
Useful in general and extremly helpful for validating the topology
management rework in terms of correctness or "bug" compatibility.
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Merge tag 'x86-core-2023-10-29-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 core updates from Thomas Gleixner:
- Limit the hardcoded topology quirk for Hygon CPUs to those which have
a model ID less than 4.
The newer models have the topology CPUID leaf 0xB correctly
implemented and are not affected.
- Make SMT control more robust against enumeration failures
SMT control was added to allow controlling SMT at boottime or
runtime. The primary purpose was to provide a simple mechanism to
disable SMT in the light of speculation attack vectors.
It turned out that the code is sensible to enumeration failures and
worked only by chance for XEN/PV. XEN/PV has no real APIC enumeration
which means the primary thread mask is not set up correctly. By
chance a XEN/PV boot ends up with smp_num_siblings == 2, which makes
the hotplug control stay at its default value "enabled". So the mask
is never evaluated.
The ongoing rework of the topology evaluation caused XEN/PV to end up
with smp_num_siblings == 1, which sets the SMT control to "not
supported" and the empty primary thread mask causes the hotplug core
to deny the bringup of the APS.
Make the decision logic more robust and take 'not supported' and 'not
implemented' into account for the decision whether a CPU should be
booted or not.
- Fake primary thread mask for XEN/PV
Pretend that all XEN/PV vCPUs are primary threads, which makes the
usage of the primary thread mask valid on XEN/PV. That is consistent
with because all of the topology information on XEN/PV is fake or
even non-existent.
- Encapsulate topology information in cpuinfo_x86
Move the randomly scattered topology data into a separate data
structure for readability and as a preparatory step for the topology
evaluation overhaul.
- Consolidate APIC ID data type to u32
It's fixed width hardware data and not randomly u16, int, unsigned
long or whatever developers decided to use.
- Cure the abuse of cpuinfo for persisting logical IDs.
Per CPU cpuinfo is used to persist the logical package and die IDs.
That's really not the right place simply because cpuinfo is subject
to be reinitialized when a CPU goes through an offline/online cycle.
Use separate per CPU data for the persisting to enable the further
topology management rework. It will be removed once the new topology
management is in place.
- Provide a debug interface for inspecting topology information
Useful in general and extremly helpful for validating the topology
management rework in terms of correctness or "bug" compatibility.
* tag 'x86-core-2023-10-29-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits)
x86/apic, x86/hyperv: Use u32 in hv_snp_boot_ap() too
x86/cpu: Provide debug interface
x86/cpu/topology: Cure the abuse of cpuinfo for persisting logical ids
x86/apic: Use u32 for wakeup_secondary_cpu[_64]()
x86/apic: Use u32 for [gs]et_apic_id()
x86/apic: Use u32 for phys_pkg_id()
x86/apic: Use u32 for cpu_present_to_apicid()
x86/apic: Use u32 for check_apicid_used()
x86/apic: Use u32 for APIC IDs in global data
x86/apic: Use BAD_APICID consistently
x86/cpu: Move cpu_l[l2]c_id into topology info
x86/cpu: Move logical package and die IDs into topology info
x86/cpu: Remove pointless evaluation of x86_coreid_bits
x86/cpu: Move cu_id into topology info
x86/cpu: Move cpu_core_id into topology info
hwmon: (fam15h_power) Use topology_core_id()
scsi: lpfc: Use topology_core_id()
x86/cpu: Move cpu_die_id into topology info
x86/cpu: Move phys_proc_id into topology info
x86/cpu: Encapsulate topology information in cpuinfo_x86
...
virtualization support is disabled in the BIOS on AMD and Hygon
platforms
- A minor cleanup
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Merge tag 'x86_cpu_for_6.7_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 cpuid updates from Borislav Petkov:
- Make sure the "svm" feature flag is cleared from /proc/cpuinfo when
virtualization support is disabled in the BIOS on AMD and Hygon
platforms
- A minor cleanup
* tag 'x86_cpu_for_6.7_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/cpu/amd: Remove redundant 'break' statement
x86/cpu: Clear SVM feature if disabled by BIOS
Fix erratum #1485 on Zen4 parts where running with STIBP disabled can
cause an #UD exception. The performance impact of the fix is negligible.
Reported-by: René Rebe <rene@exactcode.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: René Rebe <rene@exactcode.de>
Cc: <stable@kernel.org>
Link: https://lore.kernel.org/r/D99589F4-BC5D-430B-87B2-72C20370CF57@exactcode.com
The topology IDs which identify the LLC and L2 domains clearly belong to
the per CPU topology information.
Move them into cpuinfo_x86::cpuinfo_topo and get rid of the extra per CPU
data and the related exports.
This also paves the way to do proper topology evaluation during early boot
because it removes the only per CPU dependency for that.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230814085112.803864641@linutronix.de
Rename it to core_id and stick it to the other ID fields.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230814085112.566519388@linutronix.de
Rename it to pkg_id which is the terminology used in the kernel.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230814085112.329006989@linutronix.de
The topology related information is randomly scattered across cpuinfo_x86.
Create a new structure cpuinfo_topo and move in a first step initial_apicid
and apicid into it.
Aside of being better readable this is in preparation for replacing the
horribly fragile CPU topology evaluation code further down the road.
Consolidate APIC ID fields to u32 as that represents the hardware type.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230814085112.269787744@linutronix.de
When SVM is disabled by BIOS, one cannot use KVM but the
SVM feature is still shown in the output of /proc/cpuinfo.
On Intel machines, VMX is cleared by init_ia32_feat_ctl(),
so do the same on AMD and Hygon processors.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230921114940.957141-1-pbonzini@redhat.com
To support live migration, the hypervisor sets the "lowest common
denominator" of features. Probing the microcode isn't allowed because
any detected features might go away after a migration.
As Andy Cooper states:
"Linux must not probe microcode when virtualised. What it may see
instantaneously on boot (owing to MSR_PRED_CMD being fully passed
through) is not accurate for the lifetime of the VM."
Rely on the hypervisor to set the needed IBPB_BRTYPE and SBPB bits.
Fixes: 1b5277c0ea ("x86/srso: Add SRSO_NO support")
Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/3938a7209606c045a3f50305d201d840e8c834c7.1693889988.git.jpoimboe@kernel.org
Booting with mitigations=off incorrectly prevents the
X86_FEATURE_{IBPB_BRTYPE,SBPB} CPUID bits from getting set.
Also, future CPUs without X86_BUG_SRSO might still have IBPB with branch
type prediction flushing, in which case SBPB should be used instead of
IBPB. The current code doesn't allow for that.
Also, cpu_has_ibpb_brtype_microcode() has some surprising side effects
and the setting of these feature bits really doesn't belong in the
mitigation code anyway. Move it to earlier.
Fixes: fb3bd914b3 ("x86/srso: Add a Speculative RAS Overflow mitigation")
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/869a1709abfe13b673bdd10c2f4332ca253a40bc.1693889988.git.jpoimboe@kernel.org
coalescing lots of silly duplicates.
* Use static_calls() instead of indirect calls for apic->foo()
* Tons of cleanups an crap removal along the way
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Merge tag 'x86_apic_for_6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 apic updates from Dave Hansen:
"This includes a very thorough rework of the 'struct apic' handlers.
Quite a variety of them popped up over the years, especially in the
32-bit days when odd apics were much more in vogue.
The end result speaks for itself, which is a removal of a ton of code
and static calls to replace indirect calls.
If there's any breakage here, it's likely to be around the 32-bit
museum pieces that get light to no testing these days.
Summary:
- Rework apic callbacks, getting rid of unnecessary ones and
coalescing lots of silly duplicates.
- Use static_calls() instead of indirect calls for apic->foo()
- Tons of cleanups an crap removal along the way"
* tag 'x86_apic_for_6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (64 commits)
x86/apic: Turn on static calls
x86/apic: Provide static call infrastructure for APIC callbacks
x86/apic: Wrap IPI calls into helper functions
x86/apic: Mark all hotpath APIC callback wrappers __always_inline
x86/xen/apic: Mark apic __ro_after_init
x86/apic: Convert other overrides to apic_update_callback()
x86/apic: Replace acpi_wake_cpu_handler_update() and apic_set_eoi_cb()
x86/apic: Provide apic_update_callback()
x86/xen/apic: Use standard apic driver mechanism for Xen PV
x86/apic: Provide common init infrastructure
x86/apic: Wrap apic->native_eoi() into a helper
x86/apic: Nuke ack_APIC_irq()
x86/apic: Remove pointless arguments from [native_]eoi_write()
x86/apic/noop: Tidy up the code
x86/apic: Remove pointless NULL initializations
x86/apic: Sanitize APIC ID range validation
x86/apic: Prepare x2APIC for using apic::max_apic_id
x86/apic: Simplify X2APIC ID validation
x86/apic: Add max_apic_id member
x86/apic: Wrap APIC ID validation into an inline
...
Initially, it was thought that doing an innocuous division in the #DE
handler would take care to prevent any leaking of old data from the
divider but by the time the fault is raised, the speculation has already
advanced too far and such data could already have been used by younger
operations.
Therefore, do the innocuous division on every exit to userspace so that
userspace doesn't see any potentially old data from integer divisions in
kernel space.
Do the same before VMRUN too, to protect host data from leaking into the
guest too.
Fixes: 77245f1c3c ("x86/CPU/AMD: Do not leak quotient data after a division by 0")
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: <stable@kernel.org>
Link: https://lore.kernel.org/r/20230811213824.10025-1-bp@alien8.de
leads to an EFI config table ending up unmapped
- Use the correct segment selector in the 32-bit version of getcpu() in
the vDSO
- Make sure vDSO and VVAR regions are placed in the 47-bit VA range even
on 5-level paging systems
- Add models 0x90-0x91 to the range of AMD Zenbleed-affected CPUs
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Merge tag 'x86_urgent_for_v6.5_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fixes from Borislav Petkov:
- Do not parse the confidential computing blob on non-AMD hardware as
it leads to an EFI config table ending up unmapped
- Use the correct segment selector in the 32-bit version of getcpu() in
the vDSO
- Make sure vDSO and VVAR regions are placed in the 47-bit VA range
even on 5-level paging systems
- Add models 0x90-0x91 to the range of AMD Zenbleed-affected CPUs
* tag 'x86_urgent_for_v6.5_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/cpu/amd: Enable Zenbleed fix for AMD Custom APU 0405
x86/mm: Fix VDSO and VVAR placement on 5-level paging machines
x86/linkage: Fix typo of BUILD_VDSO in asm/linkage.h
x86/vdso: Choose the right GDT_ENTRY_CPUNODE for 32-bit getcpu() on 64-bit kernel
x86/sev: Do not try to parse for the CC blob on non-AMD hardware
Commit
522b1d6921 ("x86/cpu/amd: Add a Zenbleed fix")
provided a fix for the Zen2 VZEROUPPER data corruption bug affecting
a range of CPU models, but the AMD Custom APU 0405 found on SteamDeck
was not listed, although it is clearly affected by the vulnerability.
Add this CPU variant to the Zenbleed erratum list, in order to
unconditionally enable the fallback fix until a proper microcode update
is available.
Fixes: 522b1d6921 ("x86/cpu/amd: Add a Zenbleed fix")
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230811203705.1699914-1-cristian.ciocaltea@collabora.com
No point in having a wrapper around read_apic_id().
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Juergen Gross <jgross@suse.com> # Xen PV (dom0 and unpriv. guest)
Under certain circumstances, an integer division by 0 which faults, can
leave stale quotient data from a previous division operation on Zen1
microarchitectures.
Do a dummy division 0/1 before returning from the #DE exception handler
in order to avoid any leaks of potentially sensitive data.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: <stable@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
vulnerability on AMD processors. In short, this is yet another issue
where userspace poisons a microarchitectural structure which can then be
used to leak privileged information through a side channel.
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Merge tag 'x86_bugs_srso' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86/srso fixes from Borislav Petkov:
"Add a mitigation for the speculative RAS (Return Address Stack)
overflow vulnerability on AMD processors.
In short, this is yet another issue where userspace poisons a
microarchitectural structure which can then be used to leak privileged
information through a side channel"
* tag 'x86_bugs_srso' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/srso: Tie SBPB bit setting to microcode patch detection
x86/srso: Add a forgotten NOENDBR annotation
x86/srso: Fix return thunks in generated code
x86/srso: Add IBPB on VMEXIT
x86/srso: Add IBPB
x86/srso: Add SRSO_NO support
x86/srso: Add IBPB_BRTYPE support
x86/srso: Add a Speculative RAS Overflow mitigation
x86/bugs: Increase the x86 bugs vector size to two u32s
The SBPB bit in MSR_IA32_PRED_CMD is supported only after a microcode
patch has been applied so set X86_FEATURE_SBPB only then. Otherwise,
guests would attempt to set that bit and #GP on the MSR write.
While at it, make SMT detection more robust as some guests - depending
on how and what CPUID leafs their report - lead to cpu_smt_control
getting set to CPU_SMT_NOT_SUPPORTED but SRSO_NO should be set for any
guest incarnation where one simply cannot do SMT, for whatever reason.
Fixes: fb3bd914b3 ("x86/srso: Add a Speculative RAS Overflow mitigation")
Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reported-by: Salvatore Bonaccorso <carnil@debian.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Add a mitigation for the speculative return address stack overflow
vulnerability found on AMD processors.
The mitigation works by ensuring all RET instructions speculate to
a controlled location, similar to how speculation is controlled in the
retpoline sequence. To accomplish this, the __x86_return_thunk forces
the CPU to mispredict every function return using a 'safe return'
sequence.
To ensure the safety of this mitigation, the kernel must ensure that the
safe return sequence is itself free from attacker interference. In Zen3
and Zen4, this is accomplished by creating a BTB alias between the
untraining function srso_untrain_ret_alias() and the safe return
function srso_safe_ret_alias() which results in evicting a potentially
poisoned BTB entry and using that safe one for all function returns.
In older Zen1 and Zen2, this is accomplished using a reinterpretation
technique similar to Retbleed one: srso_untrain_ret() and
srso_safe_ret().
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Add a fix for the Zen2 VZEROUPPER data corruption bug where under
certain circumstances executing VZEROUPPER can cause register
corruption or leak data.
The optimal fix is through microcode but in the case the proper
microcode revision has not been applied, enable a fallback fix using
a chicken bit.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
- Finally use a CPUID bit for split lock detection instead of
enumerating every model
- Make sure automatic IBRS is set on AMD, even though the AP bringup
code does that now by replicating the MSR which contains the switch
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Merge tag 'x86_cpu_for_v6.4_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 cpu model updates from Borislav Petkov:
- Add Emerald Rapids to the list of Intel models supporting PPIN
- Finally use a CPUID bit for split lock detection instead of
enumerating every model
- Make sure automatic IBRS is set on AMD, even though the AP bringup
code does that now by replicating the MSR which contains the switch
* tag 'x86_cpu_for_v6.4_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/cpu: Add Xeon Emerald Rapids to list of CPUs that support PPIN
x86/split_lock: Enumerate architectural split lock disable bit
x86/CPU/AMD: Make sure EFER[AIBRSE] is set
So Intel introduced the FSRS ("Fast Short REP STOS") CPU capability bit,
because they seem to have done the (much simpler) REP STOS optimizations
separately and later than the REP MOVS one.
In contrast, when AMD introduced support for FSRM ("Fast Short REP
MOVS"), in the Zen 3 core, it appears to have improved the REP STOS case
at the same time, and since the FSRS bit was added by Intel later, it
doesn't show up on those AMD Zen 3 cores.
And now that we made use of FSRS for the "rep stos" conditional, that
made those AMD machines unnecessarily slower. The Intel situation where
"rep movs" is fast, but "rep stos" isn't, is just odd. The 'stos' case
is a lot simpler with no aliasing, no mutual alignment issues, no
complicated cases.
So this just sets FSRS automatically when FSRM is available on AMD
machines, to get back all the nice REP STOS goodness in Zen 3.
Reported-and-tested-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The AutoIBRS bit gets set only on the BSP as part of determining which
mitigation to enable on AMD. Setting on the APs relies on the
circumstance that the APs get booted through the trampoline and EFER
- the MSR which contains that bit - gets replicated on every AP from the
BSP.
However, this can change in the future and considering the security
implications of this bit not being set on every CPU, make sure it is set
by verifying EFER later in the boot process and on every AP.
Reported-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20230224185257.o3mcmloei5zqu7wa@treble
AMD Erratum 1386 is summarised as:
XSAVES Instruction May Fail to Save XMM Registers to the Provided
State Save Area
This piece of accidental chronomancy causes the %xmm registers to
occasionally reset back to an older value.
Ignore the XSAVES feature on all AMD Zen1/2 hardware. The XSAVEC
instruction (which works fine) is equivalent on affected parts.
[ bp: Typos, move it into the F17h-specific function. ]
Reported-by: Tavis Ormandy <taviso@gmail.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: <stable@kernel.org>
Link: https://lore.kernel.org/r/20230307174643.1240184-1-andrew.cooper3@citrix.com
Wenkuan Wang