Re: [Qemu-devel][PATCH v6 1/6] x86/cpu: Rename XSAVE related feature words.

[Sean Christopherson <sean.j.christopherson@intel.com>]

On Tue, Oct 13, 2020 at 01:19:30PM +0800, Yang Weijiang wrote:
> With more components in XSS being developed on Intel platform,
> it's necessary to clean up existing XSAVE related feature words to
> make the name clearer. It's to prepare for adding CET related support
> in following patches.
> 
> Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
> ---
>  target/i386/cpu.c        | 60 ++++++++++++++++++++--------------------
>  target/i386/cpu.h        |  6 ++--
>  target/i386/fpu_helper.c |  2 +-
>  target/i386/translate.c  |  2 +-
>  4 files changed, 35 insertions(+), 35 deletions(-)
> 
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index 588f32e136..e2891740f1 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -1050,7 +1050,7 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
>          .tcg_features = 0,
>          .unmigratable_flags = 0,
>      },
> -    [FEAT_XSAVE] = {
> +    [FEAT_XSAVE_INSTRUCTION] = {

The COMP->XCRO change is great, but I don't think XSAVE->XSAVE_INSTRUCTION
makes sense.  There is no guarantee the word will only be used for
instructions; it already blurs the line, e.g. XSAVEC also changes the behavior
of XRSTOR, and XSAVES also means the XSS MSR is available.

FWIW, I also don't find FEAT_XSAVE to be confusing.

>          .type = CPUID_FEATURE_WORD,
>          .feat_names = {
>              "xsaveopt", "xsavec", "xgetbv1", "xsaves",
> @@ -1084,7 +1084,7 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
>          .cpuid = { .eax = 6, .reg = R_EAX, },
>          .tcg_features = TCG_6_EAX_FEATURES,
>      },
> -    [FEAT_XSAVE_COMP_LO] = {
> +    [FEAT_XSAVE_XCR0_LO] = {
>          .type = CPUID_FEATURE_WORD,
>          .cpuid = {
>              .eax = 0xD,