Commit 46044f72 authored by Ben Gardon's avatar Ben Gardon Committed by Paolo Bonzini

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/+/2538Signed-off-by: default avatarBen Gardon <bgardon@google.com>
Message-Id: <20201014182700.2888246-18-bgardon@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 14881998
......@@ -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;
}
......
......@@ -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;
}
......@@ -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 */
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment