diff options
author | Sean Christopherson <seanjc@google.com> | 2023-07-28 18:35:17 -0700 |
---|---|---|
committer | Paolo Bonzini <pbonzini@redhat.com> | 2023-08-31 13:48:58 -0400 |
commit | 3cca6b262876d30aae423431e8392d8b97b044fd (patch) | |
tree | ff0b2420c68c5eaa5ab836ecfe9691b5e8ce2018 /drivers/gpu/drm/i915/gvt/kvmgt.c | |
parent | a90c367e5af63880008e21dd199dac839e0e9e0f (diff) |
drm/i915/gvt: Protect gfn hash table with vgpu_lock
Use vgpu_lock instead of KVM's mmu_lock to protect accesses to the hash
table used to track which gfns are write-protected when shadowing the
guest's GTT, and hoist the acquisition of vgpu_lock from
intel_vgpu_page_track_handler() out to its sole caller,
kvmgt_page_track_write().
This fixes a bug where kvmgt_page_track_write(), which doesn't hold
kvm->mmu_lock, could race with intel_gvt_page_track_remove() and trigger
a use-after-free.
Fixing kvmgt_page_track_write() by taking kvm->mmu_lock is not an option
as mmu_lock is a r/w spinlock, and intel_vgpu_page_track_handler() might
sleep when acquiring vgpu->cache_lock deep down the callstack:
intel_vgpu_page_track_handler()
|
|-> page_track->handler / ppgtt_write_protection_handler()
|
|-> ppgtt_handle_guest_write_page_table_bytes()
|
|-> ppgtt_handle_guest_write_page_table()
|
|-> ppgtt_handle_guest_entry_removal()
|
|-> ppgtt_invalidate_pte()
|
|-> intel_gvt_dma_unmap_guest_page()
|
|-> mutex_lock(&vgpu->cache_lock);
Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Reviewed-by: Zhi Wang <zhi.a.wang@intel.com>
Link: https://lore.kernel.org/r/20230729013535.1070024-12-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'drivers/gpu/drm/i915/gvt/kvmgt.c')
-rw-r--r-- | drivers/gpu/drm/i915/gvt/kvmgt.c | 39 |
1 files changed, 23 insertions, 16 deletions
diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c index 6f52886c4051..034be0655daa 100644 --- a/drivers/gpu/drm/i915/gvt/kvmgt.c +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c @@ -352,6 +352,8 @@ __kvmgt_protect_table_find(struct intel_vgpu *info, gfn_t gfn) { struct kvmgt_pgfn *p, *res = NULL; + lockdep_assert_held(&info->vgpu_lock); + hash_for_each_possible(info->ptable, p, hnode, gfn) { if (gfn == p->gfn) { res = p; @@ -1553,6 +1555,9 @@ int intel_gvt_page_track_add(struct intel_vgpu *info, u64 gfn) if (!test_bit(INTEL_VGPU_STATUS_ATTACHED, info->status)) return -ESRCH; + if (kvmgt_gfn_is_write_protected(info, gfn)) + return 0; + idx = srcu_read_lock(&kvm->srcu); slot = gfn_to_memslot(kvm, gfn); if (!slot) { @@ -1561,16 +1566,12 @@ int intel_gvt_page_track_add(struct intel_vgpu *info, u64 gfn) } write_lock(&kvm->mmu_lock); - - if (kvmgt_gfn_is_write_protected(info, gfn)) - goto out; - kvm_slot_page_track_add_page(kvm, slot, gfn, KVM_PAGE_TRACK_WRITE); - kvmgt_protect_table_add(info, gfn); - -out: write_unlock(&kvm->mmu_lock); + srcu_read_unlock(&kvm->srcu, idx); + + kvmgt_protect_table_add(info, gfn); return 0; } @@ -1583,6 +1584,9 @@ int intel_gvt_page_track_remove(struct intel_vgpu *info, u64 gfn) if (!test_bit(INTEL_VGPU_STATUS_ATTACHED, info->status)) return -ESRCH; + if (!kvmgt_gfn_is_write_protected(info, gfn)) + return 0; + idx = srcu_read_lock(&kvm->srcu); slot = gfn_to_memslot(kvm, gfn); if (!slot) { @@ -1591,16 +1595,11 @@ int intel_gvt_page_track_remove(struct intel_vgpu *info, u64 gfn) } write_lock(&kvm->mmu_lock); - - if (!kvmgt_gfn_is_write_protected(info, gfn)) - goto out; - kvm_slot_page_track_remove_page(kvm, slot, gfn, KVM_PAGE_TRACK_WRITE); - kvmgt_protect_table_del(info, gfn); - -out: write_unlock(&kvm->mmu_lock); srcu_read_unlock(&kvm->srcu, idx); + + kvmgt_protect_table_del(info, gfn); return 0; } @@ -1611,9 +1610,13 @@ static void kvmgt_page_track_write(struct kvm_vcpu *vcpu, gpa_t gpa, struct intel_vgpu *info = container_of(node, struct intel_vgpu, track_node); + mutex_lock(&info->vgpu_lock); + if (kvmgt_gfn_is_write_protected(info, gpa_to_gfn(gpa))) intel_vgpu_page_track_handler(info, gpa, (void *)val, len); + + mutex_unlock(&info->vgpu_lock); } static void kvmgt_page_track_flush_slot(struct kvm *kvm, @@ -1625,16 +1628,20 @@ static void kvmgt_page_track_flush_slot(struct kvm *kvm, struct intel_vgpu *info = container_of(node, struct intel_vgpu, track_node); - write_lock(&kvm->mmu_lock); + mutex_lock(&info->vgpu_lock); + for (i = 0; i < slot->npages; i++) { gfn = slot->base_gfn + i; if (kvmgt_gfn_is_write_protected(info, gfn)) { + write_lock(&kvm->mmu_lock); kvm_slot_page_track_remove_page(kvm, slot, gfn, KVM_PAGE_TRACK_WRITE); + write_unlock(&kvm->mmu_lock); + kvmgt_protect_table_del(info, gfn); } } - write_unlock(&kvm->mmu_lock); + mutex_unlock(&info->vgpu_lock); } void intel_vgpu_detach_regions(struct intel_vgpu *vgpu) |