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From: Sean Christopherson <seanjc@google.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>,
	Michael Kelley <mikelley@microsoft.com>,
	Maxim Levitsky <mlevitsk@redhat.com>,
	linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 2/6] KVM: x86: Introduce CPUID_8000_0007_EDX 'scattered' leaf
Date: Tue, 20 Sep 2022 22:52:53 +0000	[thread overview]
Message-ID: <YypEReJYrI0c7Oii@google.com> (raw)
In-Reply-To: <20220916135205.3185973-3-vkuznets@redhat.com>

On Fri, Sep 16, 2022, Vitaly Kuznetsov wrote:
> CPUID_8000_0007_EDX may come handy when X86_FEATURE_CONSTANT_TSC
> needs to be checked.
> 
> No functional change intended.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> ---
>  arch/x86/kvm/cpuid.c         | 4 ++++
>  arch/x86/kvm/reverse_cpuid.h | 9 ++++++++-
>  2 files changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 75dcf7a72605..f68b14053c9b 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -669,6 +669,10 @@ void kvm_set_cpu_caps(void)
>  	if (!tdp_enabled && IS_ENABLED(CONFIG_X86_64))
>  		kvm_cpu_cap_set(X86_FEATURE_GBPAGES);
>  
> +	kvm_cpu_cap_init_scattered(CPUID_8000_0007_EDX,
> +		SF(CONSTANT_TSC)
> +	);

The scattered leaf needs to be used in __do_cpuid_func(), e.g.

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index ffdc28684cb7..c91f23bb3605 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -1137,8 +1137,8 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
                /* L2 cache and TLB: pass through host info. */
                break;
        case 0x80000007: /* Advanced power management */
-               /* invariant TSC is CPUID.80000007H:EDX[8] */
-               entry->edx &= (1 << 8);
+               cpuid_entry_override(entry, CPUID_8000_0007_EDX);
+
                /* mask against host */
                entry->edx &= boot_cpu_data.x86_power;
                entry->eax = entry->ebx = entry->ecx = 0;

  reply	other threads:[~2022-09-20 22:53 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-16 13:51 [PATCH v3 0/6] KVM: x86: Hyper-V invariant TSC control feature Vitaly Kuznetsov
2022-09-16 13:52 ` [PATCH v3 1/6] x86/hyperv: Add HV_INVARIANT_TSC_EXPOSED define Vitaly Kuznetsov
2022-09-16 13:52 ` [PATCH v3 2/6] KVM: x86: Introduce CPUID_8000_0007_EDX 'scattered' leaf Vitaly Kuznetsov
2022-09-20 22:52   ` Sean Christopherson [this message]
2022-09-21  8:17     ` Vitaly Kuznetsov
2022-09-16 13:52 ` [PATCH v3 3/6] KVM: x86: Hyper-V invariant TSC control Vitaly Kuznetsov
2022-09-20 23:03   ` Sean Christopherson
2022-09-21  8:26     ` Vitaly Kuznetsov
2022-09-21 14:32       ` Sean Christopherson
2022-09-16 13:52 ` [PATCH v3 4/6] KVM: selftests: Rename 'msr->availble' to 'msr->fault_exepected' in hyperv_features test Vitaly Kuznetsov
2022-09-16 13:52 ` [PATCH v3 5/6] KVM: selftests: Convert hyperv_features test to using KVM_X86_CPU_FEATURE() Vitaly Kuznetsov
2022-09-16 13:52 ` [PATCH v3 6/6] KVM: selftests: Test Hyper-V invariant TSC control Vitaly Kuznetsov

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