Commit 685ca6d7 authored by Borislav Petkov's avatar Borislav Petkov Committed by H. Peter Anvin

x86, microcode, AMD: Check before applying a patch

Make sure we're actually applying a microcode patch to a core which
really needs it.

This brings only a very very very minor slowdown on F10:

0.032218828 sec vs 0.056010626 sec with this patch.

And small speedup on F15:

0.487089449 sec vs 0.180551162 sec (from perf output).

Also, fixup comments while at it.
Signed-off-by: default avatarBorislav Petkov <borislav.petkov@amd.com>
Link: http://lkml.kernel.org/r/1344361461-10076-8-git-send-email-bp@amd64.orgSigned-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent e7e632f5
...@@ -202,11 +202,18 @@ static int apply_microcode_amd(int cpu) ...@@ -202,11 +202,18 @@ static int apply_microcode_amd(int cpu)
if (mc_amd == NULL) if (mc_amd == NULL)
return 0; return 0;
wrmsrl(MSR_AMD64_PATCH_LOADER, (u64)(long)&mc_amd->hdr.data_code);
/* get patch id after patching */
rdmsr(MSR_AMD64_PATCH_LEVEL, rev, dummy); rdmsr(MSR_AMD64_PATCH_LEVEL, rev, dummy);
/* check current patch id and patch's id for match */ /* need to apply patch? */
if (rev >= mc_amd->hdr.patch_id) {
c->microcode = rev;
return 0;
}
wrmsrl(MSR_AMD64_PATCH_LOADER, (u64)(long)&mc_amd->hdr.data_code);
/* verify patch application was successful */
rdmsr(MSR_AMD64_PATCH_LEVEL, rev, dummy);
if (rev != mc_amd->hdr.patch_id) { if (rev != mc_amd->hdr.patch_id) {
pr_err("CPU%d: update failed for patch_level=0x%08x\n", pr_err("CPU%d: update failed for patch_level=0x%08x\n",
cpu, mc_amd->hdr.patch_id); cpu, mc_amd->hdr.patch_id);
......
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