linux-kernel - Re: [PATCH] kvm: fix wrong exception emulation in check

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Message-ID: <05192f9e-ef51-7630-f850-91a6064677b3@redhat.com>
Date:   Tue, 21 Sep 2021 20:00:52 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Hou Wenlong <houwenlong93@...ux.alibaba.com>, kvm@...r.kernel.org
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        Avi Kivity <avi@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kvm: fix wrong exception emulation in check_rdtsc

On 18/08/21 05:36, Hou Wenlong wrote:
> According to Intel's SDM Vol2 and AMD's APM Vol3, when
> CR4.TSD is set, use rdtsc/rdtscp instruction above privilege
> level 0 should trigger a #GP.
> 
> Fixes: d7eb82030699e ("KVM: SVM: Add intercept checks for remaining group7 instructions")
> Signed-off-by: Hou Wenlong <houwenlong93@...ux.alibaba.com>
> ---
>   arch/x86/kvm/emulate.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index 2837110e66ed..c589ac832265 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -4206,7 +4206,7 @@ static int check_rdtsc(struct x86_emulate_ctxt *ctxt)
>   	u64 cr4 = ctxt->ops->get_cr(ctxt, 4);
>   
>   	if (cr4 & X86_CR4_TSD && ctxt->ops->cpl(ctxt))
> -		return emulate_ud(ctxt);
> +		return emulate_gp(ctxt, 0);
>   
>   	return X86EMUL_CONTINUE;
>   }
> 

Queued, thanks.

Paolo