From: Paolo Bonzini <pbonzini@redhat.com>
To: Wanpeng Li <kernellwp@gmail.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>
Subject: Re: [PATCH v3 1/3] KVM: emulate: Don't inject #GP when emulating RDMPC if CR0.PE=0
Date: Tue, 19 Oct 2021 19:00:03 +0200 [thread overview]
Message-ID: <39b178d0-f3aa-9bab-e142-60f917b0f707@redhat.com> (raw)
In-Reply-To: <1634631160-67276-1-git-send-email-wanpengli@tencent.com>
On 19/10/21 10:12, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@tencent.com>
>
> SDM mentioned that, RDPMC:
>
> IF (((CR4.PCE = 1) or (CPL = 0) or (CR0.PE = 0)) and (ECX indicates a supported counter))
> THEN
> EAX := counter[31:0];
> EDX := ZeroExtend(counter[MSCB:32]);
> ELSE (* ECX is not valid or CR4.PCE is 0 and CPL is 1, 2, or 3 and CR0.PE is 1 *)
> #GP(0);
> FI;
>
> Let's add the CR0.PE is 1 checking to rdpmc emulate, though this isn't
> strictly necessary since it's impossible for CPL to be >0 if CR0.PE=0.
Why not just add a comment then instead?
Paolo
> Reviewed-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> ---
> v2 -> v3:
> * add the missing 'S'
> v1 -> v2:
> * update patch description
>
> arch/x86/kvm/emulate.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index 9a144ca8e146..ab7ec569e8c9 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -4213,6 +4213,7 @@ static int check_rdtsc(struct x86_emulate_ctxt *ctxt)
> static int check_rdpmc(struct x86_emulate_ctxt *ctxt)
> {
> u64 cr4 = ctxt->ops->get_cr(ctxt, 4);
> + u64 cr0 = ctxt->ops->get_cr(ctxt, 0);
> u64 rcx = reg_read(ctxt, VCPU_REGS_RCX);
>
> /*
> @@ -4222,7 +4223,7 @@ static int check_rdpmc(struct x86_emulate_ctxt *ctxt)
> if (enable_vmware_backdoor && is_vmware_backdoor_pmc(rcx))
> return X86EMUL_CONTINUE;
>
> - if ((!(cr4 & X86_CR4_PCE) && ctxt->ops->cpl(ctxt)) ||
> + if ((!(cr4 & X86_CR4_PCE) && ctxt->ops->cpl(ctxt) && (cr0 & X86_CR0_PE)) ||
> ctxt->ops->check_pmc(ctxt, rcx))
> return emulate_gp(ctxt, 0);
>
>
next prev parent reply other threads:[~2021-10-19 17:00 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-19 8:12 Wanpeng Li
2021-10-19 8:12 ` [PATCH v3 2/3] KVM: vPMU: Fill get_msr MSR_CORE_PERF_GLOBAL_OVF_CTRL w/ 0 Wanpeng Li
2021-10-19 16:59 ` Paolo Bonzini
2021-10-19 8:12 ` [PATCH v3 3/3] KVM: vCPU kick tax cut for running vCPU Wanpeng Li
2021-10-19 16:59 ` Paolo Bonzini
2021-10-19 17:34 ` Sean Christopherson
2021-10-20 2:49 ` Wanpeng Li
2021-10-20 6:47 ` Paolo Bonzini
2021-10-20 10:02 ` Wanpeng Li
2021-10-20 10:37 ` Paolo Bonzini
2021-10-20 10:33 ` Paolo Bonzini
2021-10-19 17:00 ` Paolo Bonzini [this message]
2021-10-20 1:56 ` [PATCH v3 1/3] KVM: emulate: Don't inject #GP when emulating RDMPC if CR0.PE=0 Wanpeng Li
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