Hello,
Below commit was ported to 6.12, but I would like to request porting to the 6.6 longterm branch we are currently using:
commit c809b0d0e52d01c30066367b2952c4c4186b1047 Author: Borislav Petkov (AMD) bp@alien8.de Date: 2024-11-19 12:21:33 +0100
x86/microcode/AMD: Flush patch buffer mapping after application [...]
The patch itself is small, but the consequence of not patching is large on affected systems (tens of seconds to minutes, of boot delay). See original discussion [1] for details.
The patch in master relies on a variable 'bsp_cpuid_1_eax' introduced in commit 94838d230a6c ("x86/microcode/AMD: Use the family,model,stepping encoded in the patch ID"), but porting that entire commit seems excessive, especially because there are several 'Fixes' commits for that one (e.g. 5343558a868e, d1744a4c975b, 1d81d85d1a19).
I think the simplest prerequisite change is (for Borislav Petkov to confirm):
diff --git a/arch/x86/kernel/cpu/microcode/amd.c b/arch/x86/kernel/cpu/microcode/amd.c index bbd1dc38ea03..555fa76bd1f3 100644 --- a/arch/x86/kernel/cpu/microcode/amd.c +++ b/arch/x86/kernel/cpu/microcode/amd.c @@ -96,6 +97,8 @@ struct cont_desc {
static u32 ucode_new_rev;
+static u32 bsp_cpuid_1_eax __ro_after_init; + /* * Microcode patch container file is prepended to the initrd in cpio * format. See Documentation/arch/x86/microcode.rst @@ -551,6 +566,7 @@ static void apply_ucode_from_containers(unsigned int cpuid_1_eax)
void load_ucode_amd_early(unsigned int cpuid_1_eax) { + bsp_cpuid_1_eax = cpuid_1_eax; return apply_ucode_from_containers(cpuid_1_eax); }
Thanks, Thomas
[1] https://lore.kernel.org/lkml/ZyulbYuvrkshfsd2@antipodes/T/