linux.git/arch/x86/kernel/cpu/microcode/amd.c, branch v6.17

x86/microcode/AMD: Handle the case of no BIOS microcode

2025-08-27T08:24:10+00:00

Machines can be shipped without any microcode in the BIOS. Which means,
the microcode patch revision is 0.

Handle that gracefully.

Fixes: 94838d230a6c ("x86/microcode/AMD: Use the family,model,stepping encoded in the patch ID")
Reported-by: Vítek Vávra 
Signed-off-by: Borislav Petkov (AMD) 
Cc:

Merge branch 'x86/msr' into x86/core, to resolve conflicts

2025-05-13T08:42:06+00:00

 Conflicts:
	arch/x86/boot/startup/sme.c
	arch/x86/coco/sev/core.c
	arch/x86/kernel/fpu/core.c
	arch/x86/kernel/fpu/xstate.c

 Semantic conflict:
	arch/x86/include/asm/sev-internal.h

Signed-off-by: Ingo Molnar

Merge branch 'x86/microcode' into x86/core, to merge dependent commits

2025-05-13T08:37:52+00:00

Prepare to resolve conflicts with an upstream series of fixes that conflict
with pending x86 changes:

  6f5bf947bab0 Merge tag 'its-for-linus-20250509' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Signed-off-by: Ingo Molnar

x86/microcode: Consolidate the loader enablement checking

2025-05-05T08:51:00+00:00

Consolidate the whole logic which determines whether the microcode loader
should be enabled or not into a single function and call it everywhere.

Well, almost everywhere - not in mk_early_pgtbl_32() because there the kernel
is running without paging enabled and checking dis_ucode_ldr et al would
require physical addresses and uglification of the code.

But since this is 32-bit, the easier thing to do is to simply map the initrd
unconditionally especially since that mapping is getting removed later anyway
by zap_early_initrd_mapping() and avoid the uglification.

In doing so, address the issue of old 486er machines without CPUID
support, not booting current kernels.

  [ mingo: Fix no previous prototype for ‘microcode_loader_disabled’ [-Wmissing-prototypes] ]

Fixes: 4c585af7180c1 ("x86/boot/32: Temporarily map initrd for microcode loading")
Signed-off-by: Borislav Petkov (AMD) 
Signed-off-by: Ingo Molnar 
Signed-off-by: Borislav Petkov (AMD) 
Cc: 
Link: https://lore.kernel.org/r/CANpbe9Wm3z8fy9HbgS8cuhoj0TREYEEkBipDuhgkWFvqX0UoVQ@mail.gmail.com

Merge tag 'v6.15-rc4' into x86/msr, to pick up fixes and resolve conflicts

2025-05-02T07:43:44+00:00

Signed-off-by: Ingo Molnar

x86/microcode/AMD: Use sha256() instead of init/update/final

2025-04-28T19:03:58+00:00

Just call sha256() instead of doing the init/update/final sequence.

No functional changes.

Signed-off-by: Eric Biggers 
Signed-off-by: Borislav Petkov (AMD) 
Link: https://lore.kernel.org/20250428183006.782501-1-ebiggers@kernel.org

x86/microcode/AMD: Extend the SHA check to Zen5, block loading of any unreleased standalone Zen5 microcode patches

2025-04-12T19:09:42+00:00

All Zen5 machines out there should get BIOS updates which update to the
correct microcode patches addressing the microcode signature issue.
However, silly people carve out random microcode blobs from BIOS
packages and think are doing other people a service this way...

Block loading of any unreleased standalone Zen5 microcode patches.

Signed-off-by: Borislav Petkov (AMD) 
Signed-off-by: Ingo Molnar 
Cc: 
Cc: Andrew Cooper 
Cc: Boris Ostrovsky 
Cc: Linus Torvalds 
Cc: Maciej S. Szmigiero 
Cc: Nikolay Borisov 
Cc: Tom Lendacky 
Link: https://lore.kernel.org/r/20250410114222.32523-1-bp@kernel.org

x86/msr: Rename 'native_wrmsrl()' to 'native_wrmsrq()'

2025-04-10T09:59:28+00:00

Suggested-by: "H. Peter Anvin" 
Signed-off-by: Ingo Molnar 
Acked-by: Peter Zijlstra (Intel) 
Cc: Juergen Gross 
Cc: Dave Hansen 
Cc: Xin Li 
Cc: Linus Torvalds

x86/microcode/AMD: Clean the cache if update did not load microcode

2025-04-07T12:46:56+00:00

If microcode did not get loaded there is no reason to keep it in the cache.
Moreover, if loading failed it will not be possible to load an earlier version
of microcode since the failed revision will always be selected from the cache
on the next reload attempt.

Since the failed revisions is not easily available at this point just clean the
whole cache. It will be rebuilt later if needed.

Signed-off-by: Boris Ostrovsky 
Signed-off-by: Borislav Petkov (AMD) 
Link: https://lore.kernel.org/r/20250327230503.1850368-3-boris.ostrovsky@oracle.com

x86/microcode/AMD: Fix __apply_microcode_amd()'s return value

2025-03-28T11:49:02+00:00

When verify_sha256_digest() fails, __apply_microcode_amd() should propagate
the failure by returning false (and not -1 which is promoted to true).

Fixes: 50cef76d5cb0 ("x86/microcode/AMD: Load only SHA256-checksummed patches")
Signed-off-by: Boris Ostrovsky 
Signed-off-by: Borislav Petkov (AMD) 
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250327230503.1850368-2-boris.ostrovsky@oracle.com