aboutsummaryrefslogtreecommitdiffstats
path: root/arch
diff options
context:
space:
mode:
authorBen Gardon <bgardon@google.com>2020-10-14 11:26:57 -0700
committerPaolo Bonzini <pbonzini@redhat.com>2020-10-23 03:42:14 -0400
commit46044f72c3826b7528339f454fe8900bae6adaaa (patch)
treea179ff355799beb92f372ebbc69ea8fee5ef529f /arch
parent14881998566d2dc0703870bbe063e8d42d780eb9 (diff)
kvm: x86/mmu: Support write protection for nesting in tdp MMU
To support nested virtualization, KVM will sometimes need to write protect pages which are part of a shadowed paging structure or are not writable in the shadowed paging structure. Add a function to write protect GFN mappings for this purpose. Tested by running kvm-unit-tests and KVM selftests on an Intel Haswell machine. This series introduced no new failures. This series can be viewed in Gerrit at: https://linux-review.googlesource.com/c/virt/kvm/kvm/+/2538 Signed-off-by: Ben Gardon <bgardon@google.com> Message-Id: <20201014182700.2888246-18-bgardon@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kvm/mmu/mmu.c4
-rw-r--r--arch/x86/kvm/mmu/tdp_mmu.c50
-rw-r--r--arch/x86/kvm/mmu/tdp_mmu.h3
3 files changed, 57 insertions, 0 deletions
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index cd1be200e2a3..4c62ac8db169 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1299,6 +1299,10 @@ bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm,
write_protected |= __rmap_write_protect(kvm, rmap_head, true);
}
+ if (kvm->arch.tdp_mmu_enabled)
+ write_protected |=
+ kvm_tdp_mmu_write_protect_gfn(kvm, slot, gfn);
+
return write_protected;
}
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 0f181f324455..1491e2f7a897 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1078,3 +1078,53 @@ void kvm_tdp_mmu_zap_collapsible_sptes(struct kvm *kvm,
kvm_mmu_put_root(kvm, root);
}
}
+
+/*
+ * Removes write access on the last level SPTE mapping this GFN and unsets the
+ * SPTE_MMU_WRITABLE bit to ensure future writes continue to be intercepted.
+ * Returns true if an SPTE was set and a TLB flush is needed.
+ */
+static bool write_protect_gfn(struct kvm *kvm, struct kvm_mmu_page *root,
+ gfn_t gfn)
+{
+ struct tdp_iter iter;
+ u64 new_spte;
+ bool spte_set = false;
+
+ tdp_root_for_each_leaf_pte(iter, root, gfn, gfn + 1) {
+ if (!is_writable_pte(iter.old_spte))
+ break;
+
+ new_spte = iter.old_spte &
+ ~(PT_WRITABLE_MASK | SPTE_MMU_WRITEABLE);
+
+ tdp_mmu_set_spte(kvm, &iter, new_spte);
+ spte_set = true;
+ }
+
+ return spte_set;
+}
+
+/*
+ * Removes write access on the last level SPTE mapping this GFN and unsets the
+ * SPTE_MMU_WRITABLE bit to ensure future writes continue to be intercepted.
+ * Returns true if an SPTE was set and a TLB flush is needed.
+ */
+bool kvm_tdp_mmu_write_protect_gfn(struct kvm *kvm,
+ struct kvm_memory_slot *slot, gfn_t gfn)
+{
+ struct kvm_mmu_page *root;
+ int root_as_id;
+ bool spte_set = false;
+
+ lockdep_assert_held(&kvm->mmu_lock);
+ for_each_tdp_mmu_root(kvm, root) {
+ root_as_id = kvm_mmu_page_as_id(root);
+ if (root_as_id != slot->as_id)
+ continue;
+
+ spte_set |= write_protect_gfn(kvm, root, gfn);
+ }
+ return spte_set;
+}
+
diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h
index 8cc902b8b9f8..6501dd2ef8e4 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.h
+++ b/arch/x86/kvm/mmu/tdp_mmu.h
@@ -40,4 +40,7 @@ void kvm_tdp_mmu_clear_dirty_pt_masked(struct kvm *kvm,
bool kvm_tdp_mmu_slot_set_dirty(struct kvm *kvm, struct kvm_memory_slot *slot);
void kvm_tdp_mmu_zap_collapsible_sptes(struct kvm *kvm,
const struct kvm_memory_slot *slot);
+
+bool kvm_tdp_mmu_write_protect_gfn(struct kvm *kvm,
+ struct kvm_memory_slot *slot, gfn_t gfn);
#endif /* __KVM_X86_MMU_TDP_MMU_H */

Privacy Policy