linux-kernel - Re: [PATCH 0/9] KVM: SVM: Fix and clean up "can emulate" mess

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Date:   Fri, 21 Jan 2022 08:30:32 +0000
From:   Liam Merwick <liam.merwick@...cle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Tom Lendacky <thomas.lendacky@....com>,
        Brijesh Singh <brijesh.singh@....com>
Subject: Re: [PATCH 0/9] KVM: SVM: Fix and clean up "can emulate" mess

On 20/01/2022 16:58, Liam Merwick wrote:
> On 20/01/2022 01:07, Sean Christopherson wrote:
>> Revert an amusing/embarassing goof reported by Liam Merwick, where KVM
>> attempts to determine if RIP is backed by a valid memslot without first
>> translating RIP to its associated GPA/GFN.  Fix the underlying bug that
>> was "fixed" by the misguided memslots check by (a) never rejecting
>> emulation for !SEV guests and (b) using the #NPF error code to determine
>> if the fault happened on the code fetch or on guest page tables, which is
>> effectively what the memslots check attempted to do.
>>
>> Further clean up, harden, and document SVM's "can emulate" helper, and
>> fix a #GP interception SEV bug found in the process of doing so.
> 
> 
> FYI: I've applied all 9 commits to a 5.15 based branch (applied cleanly)
> and the 3 stable candidates to a 5.4 based branch (applied with minor
> contextual conflicts) and have been running my SEV test case (sysbench)
> and kvm-unit-tests without issues for a number of hours now.
> 

Tested-by: Liam Merwick <liam.merwick@...cle.com>


> 
>>
>> Sean Christopherson (9):
>>    KVM: SVM: Never reject emulation due to SMAP errata for !SEV guests
>>    Revert "KVM: SVM: avoid infinite loop on NPF from bad address"
>>    KVM: SVM: Don't intercept #GP for SEV guests
>>    KVM: SVM: Explicitly require DECODEASSISTS to enable SEV support
>>    KVM: x86: Pass emulation type to can_emulate_instruction()
>>    KVM: SVM: WARN if KVM attempts emulation on #UD or #GP for SEV guests
>>    KVM: SVM: Inject #UD on attempted emulation for SEV guest w/o insn
>>      buffer
>>    KVM: SVM: Don't apply SEV+SMAP workaround on code fetch or PT access
>>    KVM: SVM: Don't kill SEV guest if SMAP erratum triggers in usermode
>>
>>   arch/x86/include/asm/kvm_host.h |   3 +-
>>   arch/x86/kvm/svm/sev.c          |   9 +-
>>   arch/x86/kvm/svm/svm.c          | 162 ++++++++++++++++++++++----------
>>   arch/x86/kvm/vmx/vmx.c          |   7 +-
>>   arch/x86/kvm/x86.c              |  11 ++-
>>   virt/kvm/kvm_main.c             |   1 -
>>   6 files changed, 135 insertions(+), 58 deletions(-)
>>
>>
>> base-commit: edb9e50dbe18394d0fc9d0494f5b6046fc912d33
>