From: Sean Christopherson <seanjc@google.com>
To: Wei Huang <wei.huang2@amd.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
pbonzini@redhat.com, vkuznets@redhat.com, joro@8bytes.org,
bp@alien8.de, tglx@linutronix.de, mingo@redhat.com,
x86@kernel.org, jmattson@google.com, wanpengli@tencent.com,
bsd@redhat.com, dgilbert@redhat.com, mlevitsk@redhat.com
Subject: Re: [PATCH 2/2] KVM: SVM: Add support for VMCB address check change
Date: Tue, 12 Jan 2021 11:18:02 -0800 [thread overview]
Message-ID: <X/316tCByxsBQP5t@google.com> (raw)
In-Reply-To: <20210112063703.539893-2-wei.huang2@amd.com>
On Tue, Jan 12, 2021, Wei Huang wrote:
> New AMD CPUs have a change that checks VMEXIT intercept on special SVM
> instructions before checking their EAX against reserved memory region.
> This change is indicated by CPUID_0x8000000A_EDX[28]. If it is 1, KVM
> doesn't need to intercept and emulate #GP faults for such instructions
> because #GP isn't supposed to be triggered.
>
> Co-developed-by: Bandan Das <bsd@redhat.com>
> Signed-off-by: Bandan Das <bsd@redhat.com>
> Signed-off-by: Wei Huang <wei.huang2@amd.com>
> ---
> arch/x86/include/asm/cpufeatures.h | 1 +
> arch/x86/kvm/svm/svm.c | 2 +-
> 2 files changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
> index 84b887825f12..ea89d6fdd79a 100644
> --- a/arch/x86/include/asm/cpufeatures.h
> +++ b/arch/x86/include/asm/cpufeatures.h
> @@ -337,6 +337,7 @@
> #define X86_FEATURE_AVIC (15*32+13) /* Virtual Interrupt Controller */
> #define X86_FEATURE_V_VMSAVE_VMLOAD (15*32+15) /* Virtual VMSAVE VMLOAD */
> #define X86_FEATURE_VGIF (15*32+16) /* Virtual GIF */
> +#define X86_FEATURE_SVME_ADDR_CHK (15*32+28) /* "" SVME addr check */
Heh, KVM should advertise this to userspace by setting the kvm_cpu_cap bit. KVM
KVM forwards relevant VM-Exits to L1 without checking if rAX points at an
invalid L1 GPA.
> /* Intel-defined CPU features, CPUID level 0x00000007:0 (ECX), word 16 */
> #define X86_FEATURE_AVX512VBMI (16*32+ 1) /* AVX512 Vector Bit Manipulation instructions*/
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 74620d32aa82..451b82df2eab 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -311,7 +311,7 @@ int svm_set_efer(struct kvm_vcpu *vcpu, u64 efer)
> svm->vmcb->save.efer = efer | EFER_SVME;
> vmcb_mark_dirty(svm->vmcb, VMCB_CR);
> /* Enable GP interception for SVM instructions if needed */
> - if (efer & EFER_SVME)
> + if ((efer & EFER_SVME) && !boot_cpu_has(X86_FEATURE_SVME_ADDR_CHK))
> set_exception_intercept(svm, GP_VECTOR);
>
> return 0;
> --
> 2.27.0
>
next prev parent reply other threads:[~2021-01-12 19:19 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-12 6:37 [PATCH 1/2] KVM: x86: Add emulation support for #GP triggered by VM instructions Wei Huang
2021-01-12 6:37 ` [PATCH 2/2] KVM: SVM: Add support for VMCB address check change Wei Huang
2021-01-12 19:18 ` Sean Christopherson [this message]
2021-01-14 11:39 ` Maxim Levitsky
2021-01-14 12:04 ` Maxim Levitsky
2021-01-12 11:09 ` [PATCH 1/2] KVM: x86: Add emulation support for #GP triggered by VM instructions Maxim Levitsky
2021-01-12 21:05 ` Wei Huang
2021-01-12 12:15 ` Vitaly Kuznetsov
2021-01-12 15:11 ` Andy Lutomirski
2021-01-12 15:17 ` Maxim Levitsky
2021-01-12 15:22 ` Andy Lutomirski
2021-01-12 15:46 ` Bandan Das
2021-01-12 15:51 ` Andy Lutomirski
2021-01-12 17:56 ` Sean Christopherson
2021-01-13 4:55 ` Wei Huang
2021-01-12 21:50 ` Wei Huang
2021-01-12 14:01 ` Paolo Bonzini
2021-01-12 17:42 ` Sean Christopherson
2021-01-13 12:35 ` Paolo Bonzini
2021-01-15 7:00 ` Wei Huang
2021-01-17 18:20 ` Paolo Bonzini
2021-01-12 17:36 ` Sean Christopherson
2021-01-12 17:59 ` Sean Christopherson
2021-01-12 18:58 ` Andy Lutomirski
2021-01-13 5:15 ` Wei Huang
2021-01-14 11:42 ` Maxim Levitsky
2021-01-13 5:03 ` Wei Huang
2021-01-13 12:40 ` Paolo Bonzini
2021-01-12 19:40 ` Sean Christopherson
2021-01-12 20:00 ` Bandan Das
2021-01-14 11:47 ` Maxim Levitsky
2021-01-14 17:19 ` Sean Christopherson
2021-01-14 11:55 ` Maxim Levitsky
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