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    SubjectRe: [PATCH v3 7/9] KVM: VMX: Add guest physical address check in EPT violation and misconfig
    On Wed, Jan 27, 2021 at 12:57 PM Jim Mattson <jmattson@google.com> wrote:
    >
    > On Wed, Jan 20, 2021 at 1:16 PM Jim Mattson <jmattson@google.com> wrote:
    > >
    > > On Fri, Jan 15, 2021 at 11:35 AM Jim Mattson <jmattson@google.com> wrote:
    > > >
    > > > On Fri, Oct 23, 2020 at 10:43 AM Paolo Bonzini <pbonzini@redhat.com> wrote:
    > > > >
    > > > > On 23/10/20 19:23, Jim Mattson wrote:
    > > > > >> The information that we need is _not_ that provided by the advanced
    > > > > >> VM-exit information (or by a page walk). If a page is neither writable
    > > > > >> nor executable, the advanced information doesn't say if the injected #PF
    > > > > >> should be a W=1 or a F=1 fault. We need the information in bits 0..2 of
    > > > > >> the exit qualification for the final access, which however is not
    > > > > >> available for the paging-structure access.
    > > > > >>
    > > > > > Are you planning to extend the emulator, then, to support all
    > > > > > instructions? I'm not sure where you are going with this.
    > > > >
    > > > > I'm going to fix the bit 8=1 case, but for bit 8=0 there's not much that
    > > > > you can do. In all likelihood the guest is buggy anyway.
    > > >
    > > > Did this drop off your radar? Are you still planning to fix the bit8=1
    > > > case to use advanced EPT exit qualification information? Or did I just
    > > > miss it?
    > >
    > > Paolo,
    > > If you're not working on this, do you mind if I ask Aaron to take a look at it?
    >
    > Ugh. The advanced EPT exit qualification contains nothing useful here,
    > AFAICT. It only contains x86 page protection information--nothing
    > about the access itself.

    BTW, I don't think this patch is complete. In particular, L0 needs to
    take first crack at any L2 #PF intercepts for present, not-reserved
    faults, to see if it needs to set the RSVD flag in the error code.

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