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The retbleed=stuff mitigation is only applicable for Intel CPUs affected
by retbleed. If this option is selected for another vendor, print a
warning and fall back to the AUTO option.
Signed-off-by: David Kaplan <david.kaplan@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/20250418161721.1855190-10-david.kaplan@amd.com
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Restructure spectre_v1 to use select/apply functions to create
consistent vulnerability handling.
Signed-off-by: David Kaplan <david.kaplan@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/20250418161721.1855190-9-david.kaplan@amd.com
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Restructure GDS mitigation to use select/apply functions to create
consistent vulnerability handling.
Define new AUTO mitigation for GDS.
Signed-off-by: David Kaplan <david.kaplan@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/20250418161721.1855190-8-david.kaplan@amd.com
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Restructure SRBDS to use select/apply functions to create consistent
vulnerability handling.
Define new AUTO mitigation for SRBDS.
Signed-off-by: David Kaplan <david.kaplan@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/20250418161721.1855190-7-david.kaplan@amd.com
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The functionality in md_clear_update_mitigation() and
md_clear_select_mitigation() is now integrated into the select/update
functions for the MDS, TAA, MMIO, and RFDS vulnerabilities.
Signed-off-by: David Kaplan <david.kaplan@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/20250418161721.1855190-6-david.kaplan@amd.com
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Restructure RFDS mitigation to use select/update/apply functions to
create consistent vulnerability handling.
[ bp: Rename the oneline helper to what it checks. ]
Signed-off-by: David Kaplan <david.kaplan@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/20250418161721.1855190-5-david.kaplan@amd.com
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Restructure MMIO mitigation to use select/update/apply functions to
create consistent vulnerability handling.
Signed-off-by: David Kaplan <david.kaplan@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/20250418161721.1855190-4-david.kaplan@amd.com
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Restructure TAA mitigation to use select/update/apply functions to
create consistent vulnerability handling.
Signed-off-by: David Kaplan <david.kaplan@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/20250418161721.1855190-3-david.kaplan@amd.com
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Restructure MDS mitigation selection to use select/update/apply
functions to create consistent vulnerability handling.
[ bp: rename and beef up comment over VERW mitigation selected var for
maximum clarity. ]
Signed-off-by: David Kaplan <david.kaplan@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/20250418161721.1855190-2-david.kaplan@amd.com
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Merge urgent fixes for dependencies.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
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Now that posted MSI and KVM harvesting of PIR is identical, extract the
code (and posted MSI's wonderful comment) to a common helper.
No functional change intended.
Link: https://lore.kernel.org/r/20250401163447.846608-9-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Track the PIR bitmap in posted interrupt descriptor structures as an array
of unsigned longs instead of using unionized arrays for KVM (u32s) versus
IRQ management (u64s). In practice, because the non-KVM usage is (sanely)
restricted to 64-bit kernels, all existing usage of the u64 variant is
already working with unsigned longs.
Using "unsigned long" for the array will allow reworking KVM's processing
of the bitmap to read/write in 64-bit chunks on 64-bit kernels, i.e. will
allow optimizing KVM by reducing the number of atomic accesses to PIR.
Opportunstically replace the open coded literals in the posted MSIs code
with the appropriate macro. Deliberately don't use ARRAY_SIZE() in the
for-loops, even though it would be cleaner from a certain perspective, in
anticipation of decoupling the processing from the array declaration.
No functional change intended.
Link: https://lore.kernel.org/r/20250401163447.846608-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Track whether or not at least one IRQ was found in PIR during the initial
loop to load PIR chunks from memory. Doing so generates slightly better
code (arguably) for processing the for-loop of XCHGs, especially for the
case where there are no pending IRQs.
Note, while PIR can be modified between the initial load and the XCHG, it
can only _gain_ new IRQs, i.e. there is no danger of a false positive due
to the final version of pir_copy[] being empty.
Opportunistically convert the boolean to an "unsigned long" and compute
the effective boolean result via bitwise-OR. Some compilers, e.g.
clang-14, need the extra "hint" to elide conditional branches.
Opportunistically rename the variable in anticipation of moving the PIR
accesses to a common helper that can be shared by posted MSIs and KVM.
Old:
<+74>: test %rdx,%rdx
<+77>: je 0xffffffff812bbeb0 <handle_pending_pir+144>
<pir[0]>
<+88>: mov $0x1,%dl>
<+90>: test %rsi,%rsi
<+93>: je 0xffffffff812bbe8c <handle_pending_pir+108>
<pir[1]>
<+106>: mov $0x1,%dl
<+108>: test %rcx,%rcx
<+111>: je 0xffffffff812bbe9e <handle_pending_pir+126>
<pir[2]>
<+124>: mov $0x1,%dl
<+126>: test %rax,%rax
<+129>: je 0xffffffff812bbeb9 <handle_pending_pir+153>
<pir[3]>
<+142>: jmp 0xffffffff812bbec1 <handle_pending_pir+161>
<+144>: xor %edx,%edx
<+146>: test %rsi,%rsi
<+149>: jne 0xffffffff812bbe7f <handle_pending_pir+95>
<+151>: jmp 0xffffffff812bbe8c <handle_pending_pir+108>
<+153>: test %dl,%dl
<+155>: je 0xffffffff812bbf8e <handle_pending_pir+366>
New:
<+74>: mov %rax,%r8
<+77>: or %rcx,%r8
<+80>: or %rdx,%r8
<+83>: or %rsi,%r8
<+86>: setne %bl
<+89>: je 0xffffffff812bbf88 <handle_pending_pir+360>
<+95>: test %rsi,%rsi
<+98>: je 0xffffffff812bbe8d <handle_pending_pir+109>
<pir[0]>
<+109>: test %rdx,%rdx
<+112>: je 0xffffffff812bbe9d <handle_pending_pir+125>
<pir[1]>
<+125>: test %rcx,%rcx
<+128>: je 0xffffffff812bbead <handle_pending_pir+141>
<pir[2]>
<+141>: test %rax,%rax
<+144>: je 0xffffffff812bbebd <handle_pending_pir+157>
<pir[3]>
Link: https://lore.kernel.org/r/20250401163447.846608-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Ensure the PIR is read exactly once at the start of handle_pending_pir(),
to guarantee that checking for an outstanding posted interrupt in a given
chuck doesn't reload the chunk from the "real" PIR. Functionally, a reload
is benign, but it would defeat the purpose of pre-loading into a copy.
Fixes: 1b03d82ba15e ("x86/irq: Install posted MSI notification handler")
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20250401163447.846608-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Recently _pgd_alloc() was switched from using __get_free_pages() to
pagetable_alloc_noprof(), which might return a compound page in case
the allocation order is larger than 0.
On x86 this will be the case if CONFIG_MITIGATION_PAGE_TABLE_ISOLATION
is set, even if PTI has been disabled at runtime.
When running as a Xen PV guest (this will always disable PTI), using
a compound page for a PGD will result in VM_BUG_ON_PGFLAGS being
triggered when the Xen code tries to pin the PGD.
Fix the Xen issue together with the not needed 8k allocation for a
PGD with PTI disabled by replacing PGD_ALLOCATION_ORDER with an
inline helper returning the needed order for PGD allocations.
Fixes: a9b3c355c2e6 ("asm-generic: pgalloc: provide generic __pgd_{alloc,free}")
Reported-by: Petr Vaněk <arkamar@atlas.cz>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Tested-by: Petr Vaněk <arkamar@atlas.cz>
Cc:stable@vger.kernel.org
Link: https://lore.kernel.org/all/20250422131717.25724-1-jgross%40suse.com
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upstream fixes
In particular we need this fix before applying subsequent changes:
d54d610243a4 ("x86/boot/sev: Avoid shared GHCB page for early memory acceptance")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Old microcode is bad for users and for kernel developers.
For users, it exposes them to known fixed security and/or functional
issues. These obviously rarely result in instant dumpster fires in
every environment. But it is as important to keep your microcode up
to date as it is to keep your kernel up to date.
Old microcode also makes kernels harder to debug. A developer looking
at an oops need to consider kernel bugs, known CPU issues and unknown
CPU issues as possible causes. If they know the microcode is up to
date, they can mostly eliminate known CPU issues as the cause.
Make it easier to tell if CPU microcode is out of date. Add a list
of released microcode. If the loaded microcode is older than the
release, tell users in a place that folks can find it:
/sys/devices/system/cpu/vulnerabilities/old_microcode
Tell kernel kernel developers about it with the existing taint
flag:
TAINT_CPU_OUT_OF_SPEC
== Discussion ==
When a user reports a potential kernel issue, it is very common
to ask them to reproduce the issue on mainline. Running mainline,
they will (independently from the distro) acquire a more up-to-date
microcode version list. If their microcode is old, they will
get a warning about the taint and kernel developers can take that
into consideration when debugging.
Just like any other entry in "vulnerabilities/", users are free to
make their own assessment of their exposure.
== Microcode Revision Discussion ==
The microcode versions in the table were generated from the Intel
microcode git repo:
8ac9378a8487 ("microcode-20241112 Release")
which as of this writing lags behind the latest microcode-20250211.
It can be argued that the versions that the kernel picks to call "old"
should be a revision or two old. Which specific version is picked is
less important to me than picking *a* version and enforcing it.
This repository contains only microcode versions that Intel has deemed
to be OS-loadable. It is quite possible that the BIOS has loaded a
newer microcode than the latest in this repo. If this happens, the
system is considered to have new microcode, not old.
Specifically, the sysfs file and taint flag answer the question:
Is the CPU running on the latest OS-loadable microcode,
or something even later that the BIOS loaded?
In other words, Intel never publishes an authoritative list of CPUs
and latest microcode revisions. Until it does, this is the best that
Linux can do.
Also note that the "intel-ucode-defs.h" file is simple, ugly and
has lots of magic numbers. That's on purpose and should allow a
single file to be shared across lots of stable kernel regardless of if
they have the new "VFM" infrastructure or not. It was generated with
a dumb script.
== FAQ ==
Q: Does this tell me if my system is secure or insecure?
A: No. It only tells you if your microcode was old when the
system booted.
Q: Should the kernel warn if the microcode list itself is too old?
A: No. New kernels will get new microcode lists, both mainline
and stable. The only way to have an old list is to be running
an old kernel in which case you have bigger problems.
Q: Is this for security or functional issues?
A: Both.
Q: If a given microcode update only has functional problems but
no security issues, will it be considered old?
A: Yes. All microcode image versions within a microcode release
are treated identically. Intel appears to make security
updates without disclosing them in the release notes. Thus,
all updates are considered to be security-relevant.
Q: Who runs old microcode?
A: Anybody with an old distro. This happens all the time inside
of Intel where there are lots of weird systems in labs that
might not be getting regular distro updates and might also
be running rather exotic microcode images.
Q: If I update my microcode after booting will it stop saying
"Vulnerable"?
A: No. Just like all the other vulnerabilies, you need to
reboot before the kernel will reassess your vulnerability.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: "Ahmed S. Darwish" <darwi@linutronix.de>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/all/20250421195659.CF426C07%40davehans-spike.ostc.intel.com
(cherry picked from commit 9127865b15eb0a1bd05ad7efe29489c44394bdc1)
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Avoid a conflict in <asm/cpufeatures.h> by merging pending x86/cpu changes.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Dave Hansen reports the following crash on a 32-bit system with
CONFIG_HIGHMEM=y and CONFIG_X86_PAE=y:
> 0xf75fe000 is the mem_map[] entry for the first page >4GB. It
> obviously wasn't allocated, thus the oops.
BUG: unable to handle page fault for address: f75fe000
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
*pdpt = 0000000002da2001 *pde = 000000000300c067 *pte = 0000000000000000
Oops: Oops: 0002 [#1] SMP NOPTI
CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 6.15.0-rc1-00288-ge618ee89561b-dirty #311 PREEMPT(undef)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
EIP: __free_pages_core+0x3c/0x74
...
Call Trace:
memblock_free_pages+0x11/0x2c
memblock_free_all+0x2ce/0x3a0
mm_core_init+0xf5/0x320
start_kernel+0x296/0x79c
i386_start_kernel+0xad/0xb0
startup_32_smp+0x151/0x154
The mem_map[] is allocated up to the end of ZONE_HIGHMEM which is defined
by max_pfn.
The bug was introduced by this recent commit:
6faea3422e3b ("arch, mm: streamline HIGHMEM freeing")
Previously, freeing of high memory was also clamped to the end of
ZONE_HIGHMEM but after this change, memblock_free_all() tries to
free memory above the of ZONE_HIGHMEM as well and that causes
access to mem_map[] entries beyond the end of the memory map.
To fix this, discard the memory after max_pfn from memblock on
32-bit systems so that core MM would be aware only of actually
usable memory.
Fixes: 6faea3422e3b ("arch, mm: streamline HIGHMEM freeing")
Reported-by: Dave Hansen <dave.hansen@intel.com>
Tested-by: Arnd Bergmann <arnd@kernel.org>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Shevchenko <andy@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Davide Ciminaghi <ciminaghi@gnudd.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: kvm@vger.kernel.org
Link: https://lore.kernel.org/r/20250413080858.743221-1-rppt@kernel.org # discussion and submission
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull misc x86 fixes from Ingo Molnar:
- Fix hypercall detection on Xen guests
- Extend the AMD microcode loader SHA check to Zen5, to block loading
of any unreleased standalone Zen5 microcode patches
- Add new Intel CPU model number for Bartlett Lake
- Fix the workaround for AMD erratum 1054
- Fix buggy early memory acceptance between SEV-SNP guests and the EFI
stub
* tag 'x86-urgent-2025-04-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/boot/sev: Avoid shared GHCB page for early memory acceptance
x86/cpu/amd: Fix workaround for erratum 1054
x86/cpu: Add CPU model number for Bartlett Lake CPUs with Raptor Cove cores
x86/microcode/AMD: Extend the SHA check to Zen5, block loading of any unreleased standalone Zen5 microcode patches
x86/xen: Fix __xen_hypercall_setfunc()
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Erratum 1054 affects AMD Zen processors that are a part of Family 17h
Models 00-2Fh and the workaround is to not set HWCR[IRPerfEn]. However,
when X86_FEATURE_ZEN1 was introduced, the condition to detect unaffected
processors was incorrectly changed in a way that the IRPerfEn bit gets
set only for unaffected Zen 1 processors.
Ensure that HWCR[IRPerfEn] is set for all unaffected processors. This
includes a subset of Zen 1 (Family 17h Models 30h and above) and all
later processors. Also clear X86_FEATURE_IRPERF on affected processors
so that the IRPerfCount register is not used by other entities like the
MSR PMU driver.
Fixes: 232afb557835 ("x86/CPU/AMD: Add X86_FEATURE_ZEN1")
Signed-off-by: Sandipan Das <sandipan.das@amd.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/caa057a9d6f8ad579e2f1abaa71efbd5bd4eaf6d.1744956467.git.sandipan.das@amd.com
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Rename rep_nop() function to what it really does.
No functional change intended.
Suggested-by: David Laight <david.laight.linux@gmail.com>
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Link: https://lore.kernel.org/r/20250418080805.83679-1-ubizjak@gmail.com
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Current minimum required version of binutils is 2.25,
which supports PAUSE instruction mnemonic.
Replace "REP; NOP" with this proper mnemonic.
No functional change intended.
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Link: https://lore.kernel.org/r/20250418080805.83679-2-ubizjak@gmail.com
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Minimum version of binutils required to compile the kernel is 2.25.
This version correctly handles the "rep" prefixes, so it is possible
to remove the semicolon, which was used to support ancient versions
of GNU as.
Due to the semicolon, the compiler considers "rep; insn" (or its
alternate "rep\n\tinsn" form) as two separate instructions. Removing
the semicolon makes asm length calculations more accurate, consequently
making scheduling and inlining decisions of the compiler more accurate.
Removing the semicolon also enables assembler checks involving "rep"
prefixes. Trying to assemble e.g. "rep addl %eax, %ebx" results in:
Error: invalid instruction `add' after `rep'
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavel Machek <pavel@kernel.org>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lore.kernel.org/r/20250418071437.4144391-2-ubizjak@gmail.com
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Add support to emulate all NOP instructions as the original uprobe
instruction.
This change speeds up uprobe on top of all NOP instructions and is a
preparation for usdt probe optimization, that will be done on top of
NOP5 instructions.
With this change the usdt probe on top of NOP5s won't take the performance
hit compared to usdt probe on top of standard NOP instructions.
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Hao Luo <haoluo@google.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20250414083647.1234007-1-jolsa@kernel.org
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The static key mmio_stale_data_clear controls the KVM-only mitigation for MMIO
Stale Data vulnerability. Rename it to reflect its purpose.
No functional change.
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250416-mmio-rename-v2-1-ad1f5488767c@linux.intel.com
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The original function name came from an overly compressed form of
'fpstate_regs' by commit:
e61d6310a0f8 ("x86/fpu: Reset permission and fpstate on exec()")
However, the term 'fpregs' typically refers to physical FPU registers. In
contrast, this function copies the init values to fpu->fpstate->regs, not
hardware registers.
Rename the function to better reflect what it actually does.
No functional change.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20250416021720.12305-11-chang.seok.bae@intel.com
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The variable was previously referenced in KVM code but the last usage was
removed by:
ea4d6938d4c0 ("x86/fpu: Replace KVMs home brewed FPU copy from user")
Remove its export symbol.
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20250416021720.12305-10-chang.seok.bae@intel.com
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The signal delivery logic was modified to always set the PKRU bit in
xregs_state->header->xfeatures by this commit:
ae6012d72fa6 ("x86/pkeys: Ensure updated PKRU value is XRSTOR'd")
However, the change derives the bitmask value using XGETBV(1), rather
than simply updating the buffer that already holds the value. Thus, this
approach induces an unnecessary dependency on XGETBV1 for PKRU handling.
Eliminate the dependency by using the established helper function.
Subsequently, remove the now-unused 'mask' argument.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Aruna Ramakrishna <aruna.ramakrishna@oracle.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tony W Wang-oc <TonyWWang-oc@zhaoxin.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20250416021720.12305-9-chang.seok.bae@intel.com
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Currently, saving register states in the signal frame, the legacy feature
bits are always set in xregs_state->header->xfeatures. This code sequence
can be generalized for reuse in similar cases.
Refactor the logic to ensure a consistent approach across similar usages.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20250416021720.12305-8-chang.seok.bae@intel.com
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Not all paths that lead to fpu__init_disable_system_xstate() currently
emit a message indicating that XSAVE has been disabled. Move the print
statement into the function to ensure the message in all cases.
Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250416021720.12305-7-chang.seok.bae@intel.com
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With securing APX against conflicting MPX, it is now ready to be enabled.
Include APX in the enabled xfeature set.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Sohil Mehta <sohil.mehta@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20250416021720.12305-5-chang.seok.bae@intel.com
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XSTATE components are architecturally independent. There is no rule
requiring their offsets in the non-compacted format to be strictly
ascending or mutually non-overlapping. However, in practice, such
overlaps have not occurred -- until now.
APX is introduced as xstate component 19, following AMX. In the
non-compacted XSAVE format, its offset overlaps with the space previously
occupied by the now-deprecated MPX feature:
45fc24e89b7c ("x86/mpx: remove MPX from arch/x86")
To prevent conflicts, the kernel must ensure the CPU never expose both
features at the same time. If so, it indicates unreliable hardware. In
such cases, XSAVE should be disabled entirely as a precautionary measure.
Add a sanity check to detect this condition and disable XSAVE if an
invalid hardware configuration is identified.
Note: MPX state components remain enabled on legacy systems solely for
KVM guest support.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Sohil Mehta <sohil.mehta@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20250416021720.12305-4-chang.seok.bae@intel.com
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Advanced Performance Extensions (APX) is associated with a new state
component number 19. To support saving and restoring of the corresponding
registers via the XSAVE mechanism, introduce the component definition
along with the necessary sanity checks.
Define the new component number, state name, and those register data
type. Then, extend the size checker to validate the register data type
and explicitly list the APX feature flag as a dependency for the new
component in xsave_cpuid_features[].
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Sohil Mehta <sohil.mehta@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20250416021720.12305-3-chang.seok.bae@intel.com
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Intel Advanced Performance Extensions (APX) introduce a new set of
general-purpose registers, managed as an extended state component via the
xstate management facility.
Before enabling this new xstate, define a feature flag to clarify the
dependency in xsave_cpuid_features[]. APX is enumerated under CPUID level
7 with EDX=1. Since this CPUID leaf is not yet allocated, place the flag
in a scattered feature word.
While this feature is intended only for userspace, exposing it via
/proc/cpuinfo is unnecessary. Instead, the existing arch_prctl(2)
mechanism with the ARCH_GET_XCOMP_SUPP option can be used to query the
feature availability.
Finally, clarify that APX depends on XSAVE.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Sohil Mehta <sohil.mehta@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20250416021720.12305-2-chang.seok.bae@intel.com
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Conflicts:
tools/arch/x86/include/asm/cpufeatures.h
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Shorten X86_FEATURE_AMD_HETEROGENEOUS_CORES to X86_FEATURE_AMD_HTR_CORES
to make the last column aligned consistently in the whole file.
No functional changes.
Suggested-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Xin Li (Intel) <xin@zytor.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250415175410.2944032-4-xin@zytor.com
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Shorten X86_FEATURE_CLEAR_BHB_LOOP_ON_VMEXIT to
X86_FEATURE_CLEAR_BHB_VMEXIT to make the last column aligned
consistently in the whole file.
There's no need to explain in the name what the mitigation does.
No functional changes.
Suggested-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Xin Li (Intel) <xin@zytor.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250415175410.2944032-3-xin@zytor.com
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Whack this thing because:
- the "unknown" handling is done only for this vuln and not for the
others
- it doesn't do anything besides reporting things differently. It
doesn't apply any mitigations - it is simply causing unnecessary
complications to the code which don't bring anything besides
maintenance overhead to what is already a very nasty spaghetti pile
- all the currently unaffected CPUs can also be in "unknown" status so
there's no need for special handling here
so get rid of it.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: David Kaplan <david.kaplan@amd.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Link: https://lore.kernel.org/r/20250414150951.5345-1-bp@kernel.org
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Collect AMD specific platform header files in <asm/amd/*.h>.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mario Limonciello <superm1@kernel.org>
Link: https://lore.kernel.org/r/20250413084144.3746608-7-mingo@kernel.org
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Collect AMD specific platform header files in <asm/amd/*.h>.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mario Limonciello <superm1@kernel.org>
Link: https://lore.kernel.org/r/20250413084144.3746608-4-mingo@kernel.org
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Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Chang S. Bae <chang.seok.bae@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/Z_ejggklB5-IWB5W@gmail.com
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A few uses of 'fps' snuck in, which is rather confusing
(to me) as it suggests frames-per-second. ;-)
Rename them to the canonical 'fpstate' name.
No change in functionality.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Chang S. Bae <chang.seok.bae@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250409211127.3544993-9-mingo@kernel.org
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PF_KTHREAD tasks
init_task's FPU state initialization was a bit of a hack:
__x86_init_fpu_begin = .;
. = __x86_init_fpu_begin + 128*PAGE_SIZE;
__x86_init_fpu_end = .;
But the init task isn't supposed to be using the FPU context
in any case, so remove the hack and add in some debug warnings.
As Linus noted in the discussion, the init task (and other
PF_KTHREAD tasks) *can* use the FPU via kernel_fpu_begin()/_end(),
but they don't need the context area because their FPU use is not
preemptible or reentrant, and they don't return to user-space.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Chang S. Bae <chang.seok.bae@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Uros Bizjak <ubizjak@gmail.com>
Link: https://lore.kernel.org/r/20250409211127.3544993-8-mingo@kernel.org
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PF_KTHREAD|PF_USER_WORKER tasks during exit
fpu__drop() and arch_release_task_struct() calls x86_task_fpu()
unconditionally, while the FPU context area will not be present
if it's the init task, and should not be in use when it's some
other type of kthread.
Return early for PF_KTHREAD or PF_USER_WORKER tasks. The debug
warning in x86_task_fpu() will catch any kthreads attempting to
use the FPU save area.
Fixed-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250409211127.3544993-7-mingo@kernel.org
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This encapsulates the fpu__drop() functionality better, and it
will also enable other changes that want to check a task for
PF_KTHREAD before calling x86_task_fpu().
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Chang S. Bae <chang.seok.bae@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250409211127.3544993-6-mingo@kernel.org
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As suggested by Oleg, remove the thread::fpu pointer, as we can
calculate it via x86_task_fpu() at compile-time.
This improves code generation a bit:
kepler:~/tip> size vmlinux.before vmlinux.after
text data bss dec hex filename
26475405 10435342 1740804 38651551 24dc69f vmlinux.before
26475339 10959630 1216516 38651485 24dc65d vmlinux.after
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Chang S. Bae <chang.seok.bae@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Uros Bizjak <ubizjak@gmail.com>
Link: https://lore.kernel.org/r/20250409211127.3544993-5-mingo@kernel.org
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Turn thread.fpu into a pointer. Since most FPU code internals work by passing
around the FPU pointer already, the code generation impact is small.
This allows us to remove the old kludge of task_struct being variable size:
struct task_struct {
...
/*
* New fields for task_struct should be added above here, so that
* they are included in the randomized portion of task_struct.
*/
randomized_struct_fields_end
/* CPU-specific state of this task: */
struct thread_struct thread;
/*
* WARNING: on x86, 'thread_struct' contains a variable-sized
* structure. It *MUST* be at the end of 'task_struct'.
*
* Do not put anything below here!
*/
};
... which creates a number of problems, such as requiring thread_struct to be
the last member of the struct - not allowing it to be struct-randomized, etc.
But the primary motivation is to allow the decoupling of task_struct from
hardware details (<asm/processor.h> in particular), and to eventually allow
the per-task infrastructure:
DECLARE_PER_TASK(type, name);
...
per_task(current, name) = val;
... which requires task_struct to be a constant size struct.
The fpu_thread_struct_whitelist() quirk to hardened usercopy can be removed,
now that the FPU structure is not embedded in the task struct anymore, which
reduces text footprint a bit.
Fixed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Chang S. Bae <chang.seok.bae@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250409211127.3544993-4-mingo@kernel.org
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This will make the removal of the task_struct::thread.fpu array
easier.
No change in functionality - code generated before and after this
commit is identical on x86-defconfig:
kepler:~/tip> diff -up vmlinux.before.asm vmlinux.after.asm
kepler:~/tip>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Chang S. Bae <chang.seok.bae@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20250409211127.3544993-3-mingo@kernel.org
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