From: Wei Huang <wehuang@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>, kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, vkuznets@redhat.com,
mlevitsk@redhat.com, seanjc@google.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, luto@amacapital.net
Subject: Re: [PATCH v3 0/4] Handle #GP for SVM execution instructions
Date: Tue, 26 Jan 2021 09:05:22 -0600 [thread overview]
Message-ID: <4b72ebd1-ace8-f03c-2e53-1c4ece0b17d8@amd.com> (raw)
In-Reply-To: <3349e153-83ae-3c55-ee88-2036b2ce38d8@redhat.com>
On 1/26/21 5:39 AM, Paolo Bonzini wrote:
> On 26/01/21 09:18, Wei Huang wrote:
>> While running SVM related instructions (VMRUN/VMSAVE/VMLOAD), some AMD
>> CPUs check EAX against reserved memory regions (e.g. SMM memory on host)
>> before checking VMCB's instruction intercept. If EAX falls into such
>> memory areas, #GP is triggered before #VMEXIT. This causes unexpected #GP
>> under nested virtualization. To solve this problem, this patchset makes
>> KVM trap #GP and emulate these SVM instuctions accordingly.
>>
>> Also newer AMD CPUs will change this behavior by triggering #VMEXIT
>> before #GP. This change is indicated by CPUID_0x8000000A_EDX[28]. Under
>> this circumstance, #GP interception is not required. This patchset
>> supports
>> the new feature.
>>
>> This patchset has been verified with vmrun_errata_test and
>> vmware_backdoor
>> tests of kvm_unit_test on the following configs. Also it was verified
>> that
>> vmware_backdoor can be turned on under nested on nested.
>> * Current CPU: nested, nested on nested
>> * New CPU with X86_FEATURE_SVME_ADDR_CHK: nested, nested on nested
>>
>> v2->v3:
>> * Change the decode function name to x86_decode_emulated_instruction()
>> * Add a new variable, svm_gp_erratum_intercept, to control
>> interception
>> * Turn on VM's X86_FEATURE_SVME_ADDR_CHK feature in svm_set_cpu_caps()
>> * Fix instruction emulation for vmware_backdoor under nested-on-nested
>> * Minor comment fixes
>>
>> v1->v2:
>> * Factor out instruction decode for sharing
>> * Re-org gp_interception() handling for both #GP and vmware_backdoor
>> * Use kvm_cpu_cap for X86_FEATURE_SVME_ADDR_CHK feature support
>> * Add nested on nested support
>>
>> Thanks,
>> -Wei
>>
>> Wei Huang (4):
>> KVM: x86: Factor out x86 instruction emulation with decoding
>> KVM: SVM: Add emulation support for #GP triggered by SVM instructions
>> KVM: SVM: Add support for SVM instruction address check change
>> KVM: SVM: Support #GP handling for the case of nested on nested
>>
>> arch/x86/include/asm/cpufeatures.h | 1 +
>> arch/x86/kvm/svm/svm.c | 128 +++++++++++++++++++++++++----
>> arch/x86/kvm/x86.c | 62 ++++++++------
>> arch/x86/kvm/x86.h | 2 +
>> 4 files changed, 152 insertions(+), 41 deletions(-)
>>
>
> Queued, thanks.
Thanks. BTW because we use kvm_cpu_cap_set() in svm_set_cpu_caps(). This
will be reflected into the CPUID received by QEMU. QEMU needs a one-line
patch to declare the new feature. I will send it out this morning.
-Wei
>
> Paolo
>
prev parent reply other threads:[~2021-01-26 15:07 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-26 8:18 [PATCH v3 0/4] Handle #GP for SVM execution instructions Wei Huang
2021-01-26 8:18 ` [PATCH v3 1/4] KVM: x86: Factor out x86 instruction emulation with decoding Wei Huang
2021-01-26 8:18 ` [PATCH v3 2/4] KVM: SVM: Add emulation support for #GP triggered by SVM instructions Wei Huang
2021-01-26 11:34 ` Paolo Bonzini
2021-01-26 11:50 ` Maxim Levitsky
2021-01-26 8:18 ` [PATCH v3 3/4] KVM: SVM: Add support for SVM instruction address check change Wei Huang
2021-01-26 11:52 ` Maxim Levitsky
2021-01-26 15:39 ` Wei Huang
2021-01-26 8:18 ` [PATCH v3 4/4] KVM: SVM: Support #GP handling for the case of nested on nested Wei Huang
2021-01-26 11:39 ` Paolo Bonzini
2021-01-26 11:59 ` Maxim Levitsky
2021-01-26 11:39 ` [PATCH v3 0/4] Handle #GP for SVM execution instructions Paolo Bonzini
2021-01-26 15:05 ` Wei Huang [this message]
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