[edk2-devel] [PATCH] UefiCpuPkg CpuCommonFeaturesLib: Remove CPU generation check
Laszlo Ersek
lersek at redhat.com
Thu May 16 13:06:26 UTC 2019
Hi Star,
On 05/16/19 12:33, Star Zeng wrote:
> BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=1679
>
> The checking to CpuInfo->CpuIdVersionInfoEcx.Bits.AESNI is enough,
> the checking to CPU generation could be removed, then the code
> could be reused by more platforms.
>
> Cc: Laszlo Ersek <lersek at redhat.com>
> Cc: Eric Dong <eric.dong at intel.com>
> Cc: Ruiyu Ni <ruiyu.ni at intel.com>
> Cc: Chandana Kumar <chandana.c.kumar at intel.com>
> Signed-off-by: Star Zeng <star.zeng at intel.com>
> ---
> UefiCpuPkg/Library/CpuCommonFeaturesLib/Aesni.c | 12 +++---------
> 1 file changed, 3 insertions(+), 9 deletions(-)
>
> diff --git a/UefiCpuPkg/Library/CpuCommonFeaturesLib/Aesni.c b/UefiCpuPkg/Library/CpuCommonFeaturesLib/Aesni.c
> index b79446ba3ca9..4a56eec1b267 100644
> --- a/UefiCpuPkg/Library/CpuCommonFeaturesLib/Aesni.c
> +++ b/UefiCpuPkg/Library/CpuCommonFeaturesLib/Aesni.c
> @@ -57,15 +57,9 @@ AesniSupport (
> MSR_SANDY_BRIDGE_FEATURE_CONFIG_REGISTER *MsrFeatureConfig;
>
> if (CpuInfo->CpuIdVersionInfoEcx.Bits.AESNI == 1) {
> - if (IS_SANDY_BRIDGE_PROCESSOR (CpuInfo->DisplayFamily, CpuInfo->DisplayModel) ||
> - IS_SILVERMONT_PROCESSOR (CpuInfo->DisplayFamily, CpuInfo->DisplayModel) ||
> - IS_XEON_5600_PROCESSOR (CpuInfo->DisplayFamily, CpuInfo->DisplayModel) ||
> - IS_XEON_E7_PROCESSOR (CpuInfo->DisplayFamily, CpuInfo->DisplayModel) ||
> - IS_XEON_PHI_PROCESSOR (CpuInfo->DisplayFamily, CpuInfo->DisplayModel)) {
> - MsrFeatureConfig = (MSR_SANDY_BRIDGE_FEATURE_CONFIG_REGISTER *) ConfigData;
> - ASSERT (MsrFeatureConfig != NULL);
> - MsrFeatureConfig[ProcessorNumber].Uint64 = AsmReadMsr64 (MSR_SANDY_BRIDGE_FEATURE_CONFIG);
> - }
> + MsrFeatureConfig = (MSR_SANDY_BRIDGE_FEATURE_CONFIG_REGISTER *) ConfigData;
> + ASSERT (MsrFeatureConfig != NULL);
> + MsrFeatureConfig[ProcessorNumber].Uint64 = AsmReadMsr64 (MSR_SANDY_BRIDGE_FEATURE_CONFIG);
> return TRUE;
> }
> return FALSE;
>
the patch and the bugzilla ticket claim that the AESNI bit's presence in
CPUID guarantees that MSR 0x13C is available.
I don't see what guarantees this. According to the latest Intel SDM Vol
4, which I just downloaded (335592-069US, January 2019),
MSR_FEATURE_CONFIG is available on the following (DisplayFamily,
DisplayModel) pairs:
- 06_37H, 06_4AH, 06_4DH, 06_5AH, 06_5DH, 06_5CH, 06_7AH
- 06_25H, 06_2CH
- 06_2FH
- 06_2AH, 06_2DH
- 06_57H
Which seems to indicate that at least *the approach* of the original
code -- i.e. the family/model checking -- is correct. (It's possible
that the family/model list has to be extended from time to time, of course.)
Anyway, I don't intend to block this patch; OVMF does not use
CpuCommonFeaturesLib, so this change cannot regress it. I will let other
UefiCpuPkg reviewers decide about this patch.
Thanks!
Laszlo
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