linux-kernel - Re: [PATCH 00/12] KVM: x86: Legal GPA fixes and cleanups

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Message-ID: <112585a1-713c-54ac-3d8b-ce913faec3a5@redhat.com>
Date:   Thu, 4 Feb 2021 11:44:09 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <seanjc@...gle.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>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>
Subject: Re: [PATCH 00/12] KVM: x86: Legal GPA fixes and cleanups

On 04/02/21 01:01, Sean Christopherson wrote:
> Add helpers to consolidate the GPA reserved bits checks that are scattered
> all over KVM, and fix a few bugs in the process.
> 
> The original motivation was simply to get rid of all the different open
> coded variations of the checks (there were a lot), but this snowballed
> into a more ambitious cleanup when I realized common helpers are more or
> less required to correctly handle repurposed GPA bits, e.g. SEV's C-bit.
> 
> The last two patches (use nested VM-Enter failure tracepoints in SVM)
> aren't directly related to the GPA checks, but the conflicts would be
> rather messy, so I included them here.
> 
> Note, the SEV C-bit changes are technically bug fixes, but getting them in
> stable kernels would require backporting this entire pile.  IMO, it's not
> worth the effort given that it's extremely unlikely anyone will encounter
> the bugs in anything but synthetic negative tests.
> 
> Based on kvm/queue, commit 3f87cb8253c3 ("KVM: X86: Expose bus lock debug
> exception to guest").

Queued 1 for 5.11 and 2-10 for 5.12; the VMCB01/VMCB02 patches are 
unlikely to make it in 5.12 so 11-12 won't be in kvm/next anytime 
soon---but you don't have to care about them anyway.

Paolo

> Sean Christopherson (12):
>    KVM: x86: Set so called 'reserved CR3 bits in LM mask' at vCPU reset
>    KVM: nSVM: Don't strip host's C-bit from guest's CR3 when reading
>      PDPTRs
>    KVM: x86: Add a helper to check for a legal GPA
>    KVM: x86: Add a helper to handle legal GPA with an alignment
>      requirement
>    KVM: VMX: Use GPA legality helpers to replace open coded equivalents
>    KVM: nSVM: Use common GPA helper to check for illegal CR3
>    KVM: x86: SEV: Treat C-bit as legal GPA bit regardless of vCPU mode
>    KVM: x86: Use reserved_gpa_bits to calculate reserved PxE bits
>    KVM: x86/mmu: Add helper to generate mask of reserved HPA bits
>    KVM: x86: Add helper to consolidate "raw" reserved GPA mask
>      calculations
>    KVM: x86: Move nVMX's consistency check macro to common code
>    KVM: nSVM: Trace VM-Enter consistency check failures
> 
>   arch/x86/include/asm/kvm_host.h |   2 +-
>   arch/x86/kvm/cpuid.c            |  20 +++++-
>   arch/x86/kvm/cpuid.h            |  24 +++++--
>   arch/x86/kvm/mmu/mmu.c          | 110 ++++++++++++++++----------------
>   arch/x86/kvm/mtrr.c             |  12 ++--
>   arch/x86/kvm/svm/nested.c       |  35 +++++-----
>   arch/x86/kvm/svm/svm.c          |   2 +-
>   arch/x86/kvm/vmx/nested.c       |  34 +++-------
>   arch/x86/kvm/vmx/vmx.c          |   2 +-
>   arch/x86/kvm/x86.c              |  11 ++--
>   arch/x86/kvm/x86.h              |   8 +++
>   11 files changed, 140 insertions(+), 120 deletions(-)
>