On 02/12/2014 07:14, Wanpeng Li wrote:
> xsaves will be exported to guest in the next patch, so revert the
> mask out xsaves patch.
>
> Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxxxxxx>
> ---
> arch/x86/kvm/cpuid.c | 10 +---------
> 1 file changed, 1 insertion(+), 9 deletions(-)
>
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index a4f5ac4..7af07571 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -320,10 +320,6 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
> F(ADX) | F(SMAP) | F(AVX512F) | F(AVX512PF) | F(AVX512ER) |
> F(AVX512CD);
>
> - /* cpuid 0xD.1.eax */
> - const u32 kvm_supported_word10_x86_features =
> - F(XSAVEOPT) | F(XSAVEC) | F(XGETBV1);
Every single bit needs to be whitelisted independently of the others, so
a full revert is not possible. We need to be careful about post-Skylake
processors introducing new bits in this cpuid leaf.
Also, you cannot just add F(XSAVES) here; you must only do it if XSAVES
is actually supported. This makes sure that nested virtualization will
_not_ present XSAVES to the guests until specific support is introduced
for XSAVES and XRSTORS exits (including the XSS exit bitmap).
In order to do this, you have to introduce a new member in kvm_x86_ops,
modeling what was done for MPX. The second patch can then implement
this new member.
Thanks,
Paolo
> /* all calls to cpuid_count() should be made on the same cpu */
> get_cpu();
>
> @@ -460,8 +456,6 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
> entry->eax &= supported;
> entry->edx &= supported >> 32;
> entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
> - if (!supported)
> - break;
>
> for (idx = 1, i = 1; idx < 64; ++idx) {
> u64 mask = ((u64)1 << idx);
> @@ -469,9 +463,7 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
> goto out;
>
> do_cpuid_1_ent(&entry[i], function, idx);
> - if (idx == 1)
> - entry[i].eax &= kvm_supported_word10_x86_features;
> - else if (entry[i].eax == 0 || !(supported & mask))
> + if (entry[i].eax == 0 || !(supported & mask))
> continue;
> entry[i].flags |=
> KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
>
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