diff options
author | Ben Gardon <bgardon@google.com> | 2020-10-14 11:26:57 -0700 |
---|---|---|
committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-10-23 03:42:14 -0400 |
commit | 46044f72c3826b7528339f454fe8900bae6adaaa (patch) | |
tree | a179ff355799beb92f372ebbc69ea8fee5ef529f | |
parent | 14881998566d2dc0703870bbe063e8d42d780eb9 (diff) | |
download | linux-46044f72c3826b7528339f454fe8900bae6adaaa.tar.bz2 |
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>
-rw-r--r-- | arch/x86/kvm/mmu/mmu.c | 4 | ||||
-rw-r--r-- | arch/x86/kvm/mmu/tdp_mmu.c | 50 | ||||
-rw-r--r-- | arch/x86/kvm/mmu/tdp_mmu.h | 3 |
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 */ |