stuartl/linux-stable
1
0
Fork 0
mirror of https://kernel.googlesource.com/pub/scm/linux/kernel/git/stable/linux-stable.git synced 2025-09-13 11:07:46 +10:00
Code Issues Releases Wiki Activity

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

Browse Source 
commit fcf8239ad6 upstream.

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

Handle that gracefully.

Fixes: 94838d230a ("x86/microcode/AMD: Use the family,model,stepping encoded in the patch ID")
Reported-by: Vítek Vávra <vit.vavra.kh@gmail.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Borislav Petkov (AMD) 2025-08-20 11:58:57 +02:00 committed by Greg Kroah-Hartman
parent f49161646e
commit c84ba4cdf4
1 changed files with 20 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
arch/x86/kernel/cpu/microcode/amd.c
View File

@ -161,8 +161,28 @@ static int cmp_id(const void *key, const void *elem)
return 1;
}
static u32 cpuid_to_ucode_rev(unsigned int val)
{
union zen_patch_rev p = {};
union cpuid_1_eax c;
c.full = val;
p.stepping = c.stepping;
p.model = c.model;
p.ext_model = c.ext_model;
p.ext_fam = c.ext_fam;
return p.ucode_rev;
}
static bool need_sha_check(u32 cur_rev)
{
if (!cur_rev) {
cur_rev = cpuid_to_ucode_rev(bsp_cpuid_1_eax);
pr_info_once("No current revision, generating the lowest one: 0x%x\n", cur_rev);
}
switch (cur_rev >> 8) {
case 0x80012: return cur_rev <= 0x800126f; break;
case 0x80082: return cur_rev <= 0x800820f; break;
@ -744,8 +764,6 @@ static struct ucode_patch *cache_find_patch(struct ucode_cpu_info *uci, u16 equi
n.equiv_cpu = equiv_cpu;
n.patch_id = uci->cpu_sig.rev;
WARN_ON_ONCE(!n.patch_id);
list_for_each_entry(p, &microcode_cache, plist)
if (patch_cpus_equivalent(p, &n, false))
return p;