diff options
| author | David Matlack <dmatlack@google.com> | 2022-01-25 23:05:15 +0000 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2022-02-10 13:50:32 -0500 |
| commit | 115111efd97c6c0e86f8b5904c6624fddcfe4f34 (patch) | |
| tree | e56472f8d5376879f8961fabb462c482e4015747 /arch | |
| parent | 932859a4e0b9fa12ba315e88e3d29f9d2f638916 (diff) | |
| download | linux-115111efd97c6c0e86f8b5904c6624fddcfe4f34.tar.bz2 | |
KVM: x86/mmu: Check SPTE writable invariants when setting leaf SPTEs
Check SPTE writable invariants when setting SPTEs rather than in
spte_can_locklessly_be_made_writable(). By the time KVM checks
spte_can_locklessly_be_made_writable(), the SPTE has long been since
corrupted.
Note that these invariants only apply to shadow-present leaf SPTEs (i.e.
not to MMIO SPTEs, non-leaf SPTEs, etc.). Add a comment explaining the
restriction and only instrument the code paths that set shadow-present
leaf SPTEs.
To account for access tracking, also check the SPTE writable invariants
when marking an SPTE as an access track SPTE. This also lets us remove
a redundant WARN from mark_spte_for_access_track().
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220125230518.1697048-3-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kvm/mmu/mmu.c | 1 | ||||
| -rw-r--r-- | arch/x86/kvm/mmu/spte.c | 9 | ||||
| -rw-r--r-- | arch/x86/kvm/mmu/spte.h | 2 | ||||
| -rw-r--r-- | arch/x86/kvm/mmu/tdp_mmu.c | 3 |
4 files changed, 6 insertions, 9 deletions
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 9f1b4711d5ea..0f9e0e95f365 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -529,6 +529,7 @@ static u64 mmu_spte_update_no_track(u64 *sptep, u64 new_spte) u64 old_spte = *sptep; WARN_ON(!is_shadow_present_pte(new_spte)); + check_spte_writable_invariants(new_spte); if (!is_shadow_present_pte(old_spte)) { mmu_spte_set(sptep, new_spte); diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c index 73cfe62fdad1..788d9d2b5536 100644 --- a/arch/x86/kvm/mmu/spte.c +++ b/arch/x86/kvm/mmu/spte.c @@ -250,14 +250,7 @@ u64 mark_spte_for_access_track(u64 spte) if (is_access_track_spte(spte)) return spte; - /* - * Making an Access Tracking PTE will result in removal of write access - * from the PTE. So, verify that we will be able to restore the write - * access in the fast page fault path later on. - */ - WARN_ONCE((spte & PT_WRITABLE_MASK) && - !spte_can_locklessly_be_made_writable(spte), - "kvm: Writable SPTE is not locklessly dirty-trackable\n"); + check_spte_writable_invariants(spte); WARN_ONCE(spte & (SHADOW_ACC_TRACK_SAVED_BITS_MASK << SHADOW_ACC_TRACK_SAVED_BITS_SHIFT), diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h index 912e66859ea0..b8fd055acdbd 100644 --- a/arch/x86/kvm/mmu/spte.h +++ b/arch/x86/kvm/mmu/spte.h @@ -339,6 +339,7 @@ static __always_inline bool is_rsvd_spte(struct rsvd_bits_validate *rsvd_check, __is_rsvd_bits_set(rsvd_check, spte, level); } +/* Note: spte must be a shadow-present leaf SPTE. */ static inline void check_spte_writable_invariants(u64 spte) { if (spte & shadow_mmu_writable_mask) @@ -352,7 +353,6 @@ static inline void check_spte_writable_invariants(u64 spte) static inline bool spte_can_locklessly_be_made_writable(u64 spte) { - check_spte_writable_invariants(spte); return spte & shadow_mmu_writable_mask; } diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index be808339a958..8ad5b3779e8b 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -452,6 +452,9 @@ static void __handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, trace_kvm_tdp_mmu_spte_changed(as_id, gfn, level, old_spte, new_spte); + if (is_leaf) + check_spte_writable_invariants(new_spte); + /* * The only times a SPTE should be changed from a non-present to * non-present state is when an MMIO entry is installed/modified/ |