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SubjectRe: [PATCH v4] KVM: x86: Add Intel CPUID.1F cpuid emulation support
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On 06/06/19 03:18, Like Xu wrote:
> Add support to expose Intel V2 Extended Topology Enumeration Leaf for
> some new systems with multiple software-visible die within each package.
>
> Because unimplemented and unexposed leaves should be explicitly reported
> as zero, there is no need to limit cpuid.0.eax to the maximum value of
> feature configuration but limit it to the highest leaf implemented in
> the current code. A single clamping seems sufficient and cheaper.
>
> Co-developed-by: Xiaoyao Li <xiaoyao.li@linux.intel.com>
> Signed-off-by: Xiaoyao Li <xiaoyao.li@linux.intel.com>
> Signed-off-by: Like Xu <like.xu@linux.intel.com>
>
> ---
>
> ==changelog==
>
> v4:
> - Limited cpuid.0.eax to the highest leaf implemented in KVM
>
> v3: https://lkml.org/lkml/2019/5/26/64
> - Refine commit message and comment
>
> v2: https://lkml.org/lkml/2019/4/25/1246
>
> - Apply cpuid.1f check rule on Intel SDM page 3-222 Vol.2A
> - Add comment to handle 0x1f anf 0xb in common code
> - Reduce check time in a descending-break style
>
> v1: https://lkml.org/lkml/2019/4/22/28
> ---
> arch/x86/kvm/cpuid.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index e18a9f9f65b5..f819011e6a13 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -426,7 +426,8 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
>
> switch (function) {
> case 0:
> - entry->eax = min(entry->eax, (u32)(f_intel_pt ? 0x14 : 0xd));
> + /* Limited to the highest leaf implemented in KVM. */
> + entry->eax = min(entry->eax, 0x1f);
> break;
> case 1:
> entry->edx &= kvm_cpuid_1_edx_x86_features;
> @@ -546,7 +547,11 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
> entry->edx = edx.full;
> break;
> }
> - /* function 0xb has additional index. */
> + /*
> + * Per Intel's SDM, the 0x1f is a superset of 0xb,
> + * thus they can be handled by common code.
> + */
> + case 0x1f:
> case 0xb: {
> int i, level_type;
>
>

Queued, thanks.

Paolo

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