linux-stable.git/arch/x86/kernel/cpu/amd.c, branch linux-rolling-stable

x86/CPU: Fix FPDSS on Zen1

2026-04-18T08:46:48+00:00

commit e55d98e7756135f32150b9b8f75d580d0d4b2dd3 upstream.

Zen1's hardware divider can leave, under certain circumstances, partial
results from previous operations.  Those results can be leaked by
another, attacker thread.

Fix that with a chicken bit.

Signed-off-by: Borislav Petkov (AMD) 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

x86/cpu/amd: Correct the microcode table for Zenbleed

2026-02-26T23:00:44+00:00

[ Upstream commit fb7bfa31b8e8569f154f2fe0ea6c2f03c0f087aa ]

The good revisions are tied to exact steppings, meaning it's not valid to
match on model number alone, let alone a range.

This is probably only a latent issue.  From public microcode archives, the
following CPUs exist 17-30-00, 17-60-00, 17-70-00 and would be captured by the
model ranges.  They're likely pre-production steppings, and likely didn't get
Zenbleed microcode, but it's still incorrect to compare them to a different
steppings revision.

Either way, convert the logic to use x86_match_min_microcode_rev(), which is
the preferred mechanism.

Fixes: 522b1d69219d ("x86/cpu/amd: Add a Zenbleed fix")
Signed-off-by: Andrew Cooper 
Signed-off-by: Ingo Molnar 
Cc: Borislav Petkov 
Cc: Mario Limonciello 
Cc: x86@kernel.org
Link: https://patch.msgid.link/20251126130352.880424-1-andrew.cooper3@citrix.com
Signed-off-by: Sasha Levin

Merge tag 'x86_misc_for_6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2025-12-02T22:16:42+00:00

Pull misc x86 updates from Dave Hansen:
 "The most significant are some changes to ensure that symbols exported
  for KVM are used only by KVM modules themselves, along with some
  related cleanups.

  In true x86/misc fashion, the other patch is completely unrelated and
  just enhances an existing pr_warn() to make it clear to users how they
  have tainted their kernel when something is mucking with MSRs.

  Summary:

   - Make MSR-induced taint easier for users to track down

   - Restrict KVM-specific exports to KVM itself"

* tag 'x86_misc_for_6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86: Restrict KVM-induced symbol exports to KVM modules where obvious/possible
  x86/mm: Drop unnecessary export of "ptdump_walk_pgd_level_debugfs"
  x86/mtrr: Drop unnecessary export of "mtrr_state"
  x86/bugs: Drop unnecessary export of "x86_spec_ctrl_base"
  x86/msr: Add CPU_OUT_OF_SPEC taint name to "unrecognized" pr_warn(msg)

x86/CPU/AMD: Add additional fixed RDSEED microcode revisions

2025-11-14T12:02:11+00:00

Microcode that resolves the RDSEED failure (SB-7055 [1]) has been released for
additional Zen5 models to linux-firmware [2]. Update the zen5_rdseed_microcode
array to cover these new models.

Fixes: 607b9fb2ce24 ("x86/CPU/AMD: Add RDSEED fix for Zen5")
Signed-off-by: Mario Limonciello 
Signed-off-by: Borislav Petkov (AMD) 
Cc: 
Link: https://www.amd.com/en/resources/product-security/bulletin/amd-sb-7055.html [1]
Link: https://gitlab.com/kernel-firmware/linux-firmware/-/commit/6167e5566900cf236f7a69704e8f4c441bc7212a [2]
Link: https://patch.msgid.link/20251113223608.1495655-1-mario.limonciello@amd.com

x86: Restrict KVM-induced symbol exports to KVM modules where obvious/possible

2025-11-12T23:29:38+00:00

Extend KVM's export macro framework to provide EXPORT_SYMBOL_FOR_KVM(),
and use the helper macro to export symbols for KVM throughout x86 if and
only if KVM will build one or more modules, and only for those modules.

To avoid unnecessary exports when CONFIG_KVM=m but kvm.ko will not be
built (because no vendor modules are selected), let arch code #define
EXPORT_SYMBOL_FOR_KVM to suppress/override the exports.

Note, the set of symbols to restrict to KVM was generated by manual search
and audit; any "misses" are due to human error, not some grand plan.

Signed-off-by: Sean Christopherson 
Signed-off-by: Dave Hansen 
Acked-by: Kai Huang 
Tested-by: Kai Huang 
Link: https://patch.msgid.link/20251112173944.1380633-5-seanjc%40google.com

x86/CPU/AMD: Add missing terminator for zen5_rdseed_microcode

2025-11-04T16:16:14+00:00

Running x86_match_min_microcode_rev() on a Zen5 CPU trips up KASAN for an out
of bounds access.

Fixes: 607b9fb2ce248 ("x86/CPU/AMD: Add RDSEED fix for Zen5")
Signed-off-by: Mario Limonciello 
Signed-off-by: Borislav Petkov (AMD) 
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20251104161007.269885-1-mario.limonciello@amd.com

x86/CPU/AMD: Extend Zen6 model range

2025-10-30T10:33:55+00:00

Add some more Zen6 models.

Signed-off-by: Borislav Petkov (AMD) 
Signed-off-by: Ingo Molnar 
Link: https://patch.msgid.link/20251029123056.19987-1-bp@kernel.org

x86/CPU/AMD: Add RDSEED fix for Zen5

2025-10-28T11:37:49+00:00

There's an issue with RDSEED's 16-bit and 32-bit register output
variants on Zen5 which return a random value of 0 "at a rate inconsistent
with randomness while incorrectly signaling success (CF=1)". Search the
web for AMD-SB-7055 for more detail.

Add a fix glue which checks microcode revisions.

  [ bp: Add microcode revisions checking, rewrite. ]

Cc: stable@vger.kernel.org
Signed-off-by: Gregory Price 
Signed-off-by: Borislav Petkov (AMD) 
Link: https://lore.kernel.org/r/20251018024010.4112396-1-gourry@gourry.net

x86/CPU/AMD: Prevent reset reasons from being retained across reboot

2025-10-15T19:38:06+00:00

The S5_RESET_STATUS register is parsed on boot and printed to kmsg.
However, this could sometimes be misleading and lead to users wasting a
lot of time on meaningless debugging for two reasons:

* Some bits are never cleared by hardware. It's the software's
responsibility to clear them as per the Processor Programming Reference
(see [1]).

* Some rare hardware-initiated platform resets do not update the
register at all.

In both cases, a previous reboot could leave its trace in the register,
resulting in users seeing unrelated reboot reasons while debugging random
reboots afterward.

Write the read value back to the register in order to clear all reason bits
since they are write-1-to-clear while the others must be preserved.

  [1]: https://bugzilla.kernel.org/show_bug.cgi?id=206537#attach_303991

  [ bp: Massage commit message. ]

Fixes: ab8131028710 ("x86/CPU/AMD: Print the reason for the last reset")
Signed-off-by: Rong Zhang 
Signed-off-by: Borislav Petkov (AMD) 
Reviewed-by: Mario Limonciello (AMD) 
Reviewed-by: Yazen Ghannam 
Cc: 
Link: https://lore.kernel.org/all/20250913144245.23237-1-i@rong.moe/

Merge tag 'x86_tdx_for_6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2025-10-04T17:01:30+00:00

Pull x86 TDX updates from Dave Hansen:
 "The biggest change here is making TDX and kexec play nicely together.

  Before this, the memory encryption hardware (which doesn't respect
  cache coherency) could write back old cachelines on top of data in the
  new kernel, so kexec and TDX were made mutually exclusive. This
  removes the limitation.

  There is also some work to tighten up a hardware bug workaround and
  some MAINTAINERS updates.

   - Make TDX and kexec work together

    - Skip TDX bug workaround when the bug is not present

    - Update maintainers entries"

* tag 'x86_tdx_for_6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/virt/tdx: Use precalculated TDVPR page physical address
  KVM/TDX: Explicitly do WBINVD when no more TDX SEAMCALLs
  x86/virt/tdx: Update the kexec section in the TDX documentation
  x86/virt/tdx: Remove the !KEXEC_CORE dependency
  x86/kexec: Disable kexec/kdump on platforms with TDX partial write erratum
  x86/virt/tdx: Mark memory cache state incoherent when making SEAMCALL
  x86/sme: Use percpu boolean to control WBINVD during kexec
  x86/kexec: Consolidate relocate_kernel() function parameters
  x86/tdx: Skip clearing reclaimed pages unless X86_BUG_TDX_PW_MCE is present
  x86/tdx: Tidy reset_pamt functions
  x86/tdx: Eliminate duplicate code in tdx_clear_page()
  MAINTAINERS: Add KVM mail list to the TDX entry
  MAINTAINERS: Add Rick Edgecombe as a TDX reviewer
  MAINTAINERS: Update the file list in the TDX entry.