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

[Liam Merwick]

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@xxxxxxxxxx>


> > 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