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    SubjectRe: [PATCHv2 47/59] kvm, x86, mmu: setup MKTME keyID to spte for given PFN
    Date
    On 7/31/19 10:08 AM, Kirill A. Shutemov wrote:
    > From: Kai Huang <kai.huang@linux.intel.com>
    >
    > Setup keyID to SPTE, which will be eventually programmed to shadow MMU
    > or EPT table, according to page's associated keyID, so that guest is
    > able to use correct keyID to access guest memory.
    >
    > Note current shadow_me_mask doesn't suit MKTME's needs, since for MKTME
    > there's no fixed memory encryption mask, but can vary from keyID 1 to
    > maximum keyID, therefore shadow_me_mask remains 0 for MKTME.
    >
    > Signed-off-by: Kai Huang <kai.huang@linux.intel.com>
    > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
    > ---
    > arch/x86/kvm/mmu.c | 18 +++++++++++++++++-
    > 1 file changed, 17 insertions(+), 1 deletion(-)
    >
    > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
    > index 8f72526e2f68..b8742e6219f6 100644
    > --- a/arch/x86/kvm/mmu.c
    > +++ b/arch/x86/kvm/mmu.c
    > @@ -2936,6 +2936,22 @@ static bool kvm_is_mmio_pfn(kvm_pfn_t pfn)
    > #define SET_SPTE_WRITE_PROTECTED_PT BIT(0)
    > #define SET_SPTE_NEED_REMOTE_TLB_FLUSH BIT(1)
    >
    > +static u64 get_phys_encryption_mask(kvm_pfn_t pfn)
    > +{
    > +#ifdef CONFIG_X86_INTEL_MKTME
    > + struct page *page;
    > +
    > + if (!pfn_valid(pfn))
    > + return 0;
    > +
    > + page = pfn_to_page(pfn);
    > +
    > + return ((u64)page_keyid(page)) << mktme_keyid_shift();
    > +#else
    > + return shadow_me_mask;
    > +#endif
    > +}

    This patch breaks AMD virtualization (SVM) in general (non-SEV and SEV
    guests) when SME is active. Shouldn't this be a run time, vs build time,
    check for MKTME being active?

    Thanks,
    Tom

    > +
    > static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
    > unsigned pte_access, int level,
    > gfn_t gfn, kvm_pfn_t pfn, bool speculative,
    > @@ -2982,7 +2998,7 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
    > pte_access &= ~ACC_WRITE_MASK;
    >
    > if (!kvm_is_mmio_pfn(pfn))
    > - spte |= shadow_me_mask;
    > + spte |= get_phys_encryption_mask(pfn);
    >
    > spte |= (u64)pfn << PAGE_SHIFT;
    >
    >
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