From: Mihai Dontu <mdontu@xxxxxxxxxxxxxxx>
These are helpers used by the introspection subsystem to adjust the SPTE
rwx flags. At present, the code assumes we're deadling with 4-level
hardware shadow page tables.
Signed-off-by: Mihai Dontu <mdontu@xxxxxxxxxxxxxxx>
---
arch/x86/kvm/mmu.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
arch/x86/kvm/mmu.h | 3 +++
2 files changed, 78 insertions(+)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index cb8225969255..12e4c33ff879 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -5350,3 +5350,78 @@ void kvm_mmu_module_exit(void)
unregister_shrinker(&mmu_shrinker);
mmu_audit_disable();
}
+
+u64 kvm_mmu_get_spte(struct kvm *kvm, struct kvm_vcpu *vcpu, gpa_t gpa)
+{
+ u64 spte = -1;
+ unsigned int c = 0;
+ const u64 mask = PT_PRESENT_MASK | PT_WRITABLE_MASK | PT_USER_MASK;
+ struct kvm_shadow_walk_iterator iterator;
+
+ spin_lock(&kvm->mmu_lock);
+ if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
+ goto error;
+ for_each_shadow_entry(vcpu, gpa & PAGE_MASK, iterator) {
+ u64 __spte = *iterator.sptep;
+
+ if (!(__spte & mask))
+ break;
+ else if (++c == PT64_ROOT_LEVEL) {
+ spte = __spte;
+ break;
+ }
+ }
+ if (spte == (u64) -1)
+ goto error;
+ spin_unlock(&kvm->mmu_lock);
+ return spte & mask;
+error:
+ spin_unlock(&kvm->mmu_lock);
+ return -ENOENT;
+}
+
+int kvm_mmu_set_spte(struct kvm *kvm, struct kvm_vcpu *vcpu, gpa_t gpa,
+ unsigned int r, unsigned int w, unsigned int x)
+{
+ int flush = 0;
+ u64 *pspte[4] = { };
+ u64 spte;
+ u64 old_spte;
+ unsigned int c = 0;
+ const u64 mask = PT_PRESENT_MASK | PT_WRITABLE_MASK | PT_USER_MASK;
+ struct kvm_shadow_walk_iterator iterator;
+
+ spin_lock(&kvm->mmu_lock);
+ if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
+ goto error;
+ for_each_shadow_entry(vcpu, gpa & PAGE_MASK, iterator) {
+ u64 __spte = *iterator.sptep;
+
+ if (!(__spte & mask))
+ break;
+ pspte[c++] = iterator.sptep;
+ }
+ if (c < PT64_ROOT_LEVEL || !pspte[c - 1])
+ goto error;
+ c--;
+ old_spte = *pspte[c];
+ spte = old_spte & ~mask;
+ if (r)
+ spte |= PT_PRESENT_MASK;
+ if (w)
+ spte |= PT_WRITABLE_MASK;
+ if (x)
+ spte |= PT_USER_MASK;
+ if (old_spte != spte)
+ flush |= mmu_spte_update(pspte[c], spte);
+ while (c-- > 0) {
+ spte = *pspte[c];
+ if ((spte & mask) != mask)
+ flush |= mmu_spte_update(pspte[c], spte | mask);
+ }
+ spin_unlock(&kvm->mmu_lock);
+ return flush;
+error:
+ spin_unlock(&kvm->mmu_lock);
+ return -ENOENT;
+}
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 330bf3a811fb..82246fdc0479 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -204,4 +204,7 @@ void kvm_mmu_gfn_allow_lpage(struct kvm_memory_slot *slot, gfn_t gfn);
bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm,
struct kvm_memory_slot *slot, u64 gfn);
int kvm_arch_write_log_dirty(struct kvm_vcpu *vcpu);
+u64 kvm_mmu_get_spte(struct kvm *kvm, struct kvm_vcpu *vcpu, gpa_t gpa);
+int kvm_mmu_set_spte(struct kvm *kvm, struct kvm_vcpu *vcpu, gpa_t gpa,
+ unsigned int r, unsigned int w, unsigned int x);
#endif
--
2.12.2
