lkml.org 
[lkml]   [2012]   [Aug]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH v0 07/12] x86, microcode, AMD: Check before applying a patch
    Date
    From: Borislav Petkov <borislav.petkov@amd.com>

    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>
    ---
    arch/x86/kernel/microcode_amd.c | 13 ++++++++++---
    1 file changed, 10 insertions(+), 3 deletions(-)

    diff --git a/arch/x86/kernel/microcode_amd.c b/arch/x86/kernel/microcode_amd.c
    index 94213387a3d1..8fdf7d99b804 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);
    --
    1.7.11.rc1


    \
     
     \ /
      Last update: 2012-08-07 21:43    [W:0.030 / U:33.020 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site