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From: Paolo Bonzini <pbonzini@redhat.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>, kvm@vger.kernel.org
Cc: Sean Christopherson <seanjc@google.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>
Subject: Re: [PATCH] KVM: x86: Supplement __cr4_reserved_bits() with X86_FEATURE_PCID check
Date: Mon, 1 Feb 2021 15:43:51 +0100	[thread overview]
Message-ID: <c35f656d-1fff-8c5b-42a5-575c161e4209@redhat.com> (raw)
In-Reply-To: <20210201142843.108190-1-vkuznets@redhat.com>

On 01/02/21 15:28, Vitaly Kuznetsov wrote:
> Commit 7a873e455567 ("KVM: selftests: Verify supported CR4 bits can be set
> before KVM_SET_CPUID2") reveals that KVM allows to set X86_CR4_PCIDE even
> when PCID support is missing:
> 
> ==== Test Assertion Failure ====
>    x86_64/set_sregs_test.c:41: rc
>    pid=6956 tid=6956 - Invalid argument
>       1	0x000000000040177d: test_cr4_feature_bit at set_sregs_test.c:41
>       2	0x00000000004014fc: main at set_sregs_test.c:119
>       3	0x00007f2d9346d041: ?? ??:0
>       4	0x000000000040164d: _start at ??:?
>    KVM allowed unsupported CR4 bit (0x20000)
> 
> Add X86_FEATURE_PCID feature check to __cr4_reserved_bits() to make
> kvm_is_valid_cr4() fail.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> ---
>   arch/x86/kvm/x86.h | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
> index c5ee0f5ce0f1..0f727b50bd3d 100644
> --- a/arch/x86/kvm/x86.h
> +++ b/arch/x86/kvm/x86.h
> @@ -425,6 +425,8 @@ bool kvm_msr_allowed(struct kvm_vcpu *vcpu, u32 index, u32 type);
>   		__reserved_bits |= X86_CR4_UMIP;        \
>   	if (!__cpu_has(__c, X86_FEATURE_VMX))           \
>   		__reserved_bits |= X86_CR4_VMXE;        \
> +	if (!__cpu_has(__c, X86_FEATURE_PCID))          \
> +		__reserved_bits |= X86_CR4_PCIDE;       \
>   	__reserved_bits;                                \
>   })
>   
> 

Queued, thanks.

Paolo


      reply	other threads:[~2021-02-01 14:46 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-01 14:28 [PATCH] KVM: x86: Supplement __cr4_reserved_bits() with X86_FEATURE_PCID check Vitaly Kuznetsov
2021-02-01 14:43 ` Paolo Bonzini [this message]

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