From: Paolo Bonzini <pbonzini@redhat.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>,
Peter Xu <peterx@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Vitaly Kuznetsov <vkuznets@redhat.com>
Subject: Re: [PATCH 1/2] KVM: X86: Move ignore_msrs handling upper the stack
Date: Thu, 25 Jun 2020 10:09:13 +0200 [thread overview]
Message-ID: <1cebc562-89e9-3806-bb3c-771946fc64f3@redhat.com> (raw)
In-Reply-To: <20200625061544.GC2141@linux.intel.com>
On 25/06/20 08:15, Sean Christopherson wrote:
> IMO, kvm_cpuid() is simply buggy. If KVM attempts to access a non-existent
> MSR then it darn well should warn.
>
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 8a294f9747aa..7ef7283011d6 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -1013,7 +1013,8 @@ bool kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx,
> *ebx = entry->ebx;
> *ecx = entry->ecx;
> *edx = entry->edx;
> - if (function == 7 && index == 0) {
> + if (function == 7 && index == 0 && (*ebx | (F(RTM) | F(HLE))) &&
> + (vcpu->arch.arch_capabilities & ARCH_CAP_TSX_CTRL_MSR)) {
> u64 data;
> if (!__kvm_get_msr(vcpu, MSR_IA32_TSX_CTRL, &data, true) &&
> (data & TSX_CTRL_CPUID_CLEAR))
>
That works too, but I disagree that warning is the correct behavior
here. It certainly should warn as long as kvm_get_msr blindly returns
zero. However, for a guest it's fine to access a potentially
non-existent MSR if you're ready to trap the #GP, and the point of this
series is to let cpuid.c or any other KVM code do the same.
Paolo
next prev parent reply other threads:[~2020-06-25 8:09 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-22 22:04 [PATCH 0/2] KVM: X86: A few fixes around ignore_msrs Peter Xu
2020-06-22 22:04 ` [PATCH 1/2] KVM: X86: Move ignore_msrs handling upper the stack Peter Xu
2020-06-25 6:15 ` Sean Christopherson
2020-06-25 8:09 ` Paolo Bonzini [this message]
2020-06-25 16:25 ` Sean Christopherson
2020-06-25 17:45 ` Sean Christopherson
2020-06-25 18:44 ` Paolo Bonzini
2020-06-26 15:56 ` Sean Christopherson
2020-06-26 17:37 ` Peter Xu
2020-06-26 17:46 ` Sean Christopherson
2020-06-26 18:07 ` Peter Xu
2020-06-26 18:18 ` Sean Christopherson
2020-06-26 19:11 ` Peter Xu
2020-06-27 14:24 ` Paolo Bonzini
2020-06-30 15:47 ` Sean Christopherson
2020-07-09 18:22 ` Peter Xu
2020-07-09 18:24 ` Paolo Bonzini
2020-07-09 18:34 ` Peter Xu
2020-07-09 19:24 ` Sean Christopherson
2020-07-09 21:09 ` Peter Xu
2020-07-09 21:26 ` Sean Christopherson
2020-07-09 21:50 ` Peter Xu
2020-07-09 22:11 ` Paolo Bonzini
2020-07-10 4:58 ` Sean Christopherson
2020-06-22 22:04 ` [PATCH 2/2] KVM: X86: Do the same ignore_msrs check for feature msrs Peter Xu
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