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KVM: x86/mmu: Handle MMIO SPTEs directly in mmu_set_spte()

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Now that it should be impossible to convert a valid SPTE to an MMIO SPTE,
handle MMIO SPTEs early in mmu_set_spte() without going through
set_spte() and all the logic for removing an existing, valid SPTE.
The other caller of set_spte(), FNAME(sync_page)(), explicitly handles
MMIO SPTEs prior to calling set_spte().

This simplifies mmu_set_spte() and set_spte(), and also "fixes" an oddity
where MMIO SPTEs are traced by both trace_kvm_mmu_set_spte() and
trace_mark_mmio_spte().

Note, mmu_spte_set() will WARN if this new approach causes KVM to create
an MMIO SPTE overtop a valid SPTE.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210225204749.1512652-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson
2021-02-25 12:47:32 -08:00
committed by Paolo Bonzini
parent 30ab5901da
commit a54aa15c6b
1 changed files with 5 additions and 17 deletions
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22
arch/x86/kvm/mmu/mmu.c
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@@ -236,17 +236,6 @@ static unsigned get_mmio_spte_access(u64 spte)
return spte & shadow_mmio_access_mask;
}
static bool set_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, gfn_t gfn,
kvm_pfn_t pfn, unsigned int access)
{
if (unlikely(is_noslot_pfn(pfn))) {
mark_mmio_spte(vcpu, sptep, gfn, access);
return true;
}
return false;
}
static bool check_mmio_spte(struct kvm_vcpu *vcpu, u64 spte)
{
u64 kvm_gen, spte_gen, gen;
@@ -2563,9 +2552,6 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
struct kvm_mmu_page *sp;
int ret;
if (set_mmio_spte(vcpu, sptep, gfn, pfn, pte_access))
return 0;
sp = sptep_to_sp(sptep);
ret = make_spte(vcpu, pte_access, level, gfn, pfn, *sptep, speculative,
@@ -2595,6 +2581,11 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
pgprintk("%s: spte %llx write_fault %d gfn %llx\n", __func__,
*sptep, write_fault, gfn);
if (unlikely(is_noslot_pfn(pfn))) {
mark_mmio_spte(vcpu, sptep, gfn, pte_access);
return RET_PF_EMULATE;
}
if (is_shadow_present_pte(*sptep)) {
/*
* If we overwrite a PTE page pointer with a 2MB PMD, unlink
@@ -2628,9 +2619,6 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
kvm_flush_remote_tlbs_with_address(vcpu->kvm, gfn,
KVM_PAGES_PER_HPAGE(level));
if (unlikely(is_mmio_spte(*sptep)))
ret = RET_PF_EMULATE;
/*
* The fault is fully spurious if and only if the new SPTE and old SPTE
* are identical, and emulation is not required.