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| author | Borislav Petkov <borislav.petkov@amd.com> | 2012-06-20 14:17:51 (GMT) |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2012-08-22 23:15:41 (GMT) |
| commit | 685ca6d797af9d41164dd64dd60145d4946fc152 (patch) | |
| tree | b6a867ea37b5f9c03c3819570243ccb34c97ef62 /arch/x86/kernel | |
| parent | e7e632f5ba240fbc313c49ed6559681ea57534e9 (diff) | |
| download | linux-fsl-qoriq-685ca6d797af9d41164dd64dd60145d4946fc152.tar.xz | |
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: Borislav Petkov <borislav.petkov@amd.com>
Link: http://lkml.kernel.org/r/1344361461-10076-8-git-send-email-bp@amd64.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/kernel')
| -rw-r--r-- | arch/x86/kernel/microcode_amd.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/arch/x86/kernel/microcode_amd.c b/arch/x86/kernel/microcode_amd.c index 9421338..8fdf7d9 100644 --- a/arch/x86/kernel/microcode_amd.c +++ b/arch/x86/kernel/microcode_amd.c @@ -202,11 +202,18 @@ static int apply_microcode_amd(int cpu) if (mc_amd == NULL) 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); - /* 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) { pr_err("CPU%d: update failed for patch_level=0x%08x\n", cpu, mc_amd->hdr.patch_id); |