diff options
| author | Michal Luczaj <mhal@rbox.co> | 2022-10-13 21:12:19 +0000 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2022-10-27 06:47:53 -0400 |
| commit | 52491a38b2c2411f3f0229dc6ad610349c704a41 (patch) | |
| tree | 5cb93429b46eebe321ca3769e655d8508331ab23 /virt/kvm | |
| parent | 1c1a41497ab879ac9608f3047f230af833eeef3d (diff) | |
KVM: Initialize gfn_to_pfn_cache locks in dedicated helper
Move the gfn_to_pfn_cache lock initialization to another helper and
call the new helper during VM/vCPU creation. There are race
conditions possible due to kvm_gfn_to_pfn_cache_init()'s
ability to re-initialize the cache's locks.
For example: a race between ioctl(KVM_XEN_HVM_EVTCHN_SEND) and
kvm_gfn_to_pfn_cache_init() leads to a corrupted shinfo gpc lock.
(thread 1) | (thread 2)
|
kvm_xen_set_evtchn_fast |
read_lock_irqsave(&gpc->lock, ...) |
| kvm_gfn_to_pfn_cache_init
| rwlock_init(&gpc->lock)
read_unlock_irqrestore(&gpc->lock, ...) |
Rename "cache_init" and "cache_destroy" to activate+deactivate to
avoid implying that the cache really is destroyed/freed.
Note, there more races in the newly named kvm_gpc_activate() that will
be addressed separately.
Fixes: 982ed0de4753 ("KVM: Reinstate gfn_to_pfn_cache with invalidation support")
Cc: stable@vger.kernel.org
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
[sean: call out that this is a bug fix]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221013211234.1318131-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt/kvm')
| -rw-r--r-- | virt/kvm/pfncache.c | 21 |
1 files changed, 12 insertions, 9 deletions
diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c index 68ff41d39545..08f97cf97264 100644 --- a/virt/kvm/pfncache.c +++ b/virt/kvm/pfncache.c @@ -346,17 +346,20 @@ void kvm_gfn_to_pfn_cache_unmap(struct kvm *kvm, struct gfn_to_pfn_cache *gpc) } EXPORT_SYMBOL_GPL(kvm_gfn_to_pfn_cache_unmap); +void kvm_gpc_init(struct gfn_to_pfn_cache *gpc) +{ + rwlock_init(&gpc->lock); + mutex_init(&gpc->refresh_lock); +} +EXPORT_SYMBOL_GPL(kvm_gpc_init); -int kvm_gfn_to_pfn_cache_init(struct kvm *kvm, struct gfn_to_pfn_cache *gpc, - struct kvm_vcpu *vcpu, enum pfn_cache_usage usage, - gpa_t gpa, unsigned long len) +int kvm_gpc_activate(struct kvm *kvm, struct gfn_to_pfn_cache *gpc, + struct kvm_vcpu *vcpu, enum pfn_cache_usage usage, + gpa_t gpa, unsigned long len) { WARN_ON_ONCE(!usage || (usage & KVM_GUEST_AND_HOST_USE_PFN) != usage); if (!gpc->active) { - rwlock_init(&gpc->lock); - mutex_init(&gpc->refresh_lock); - gpc->khva = NULL; gpc->pfn = KVM_PFN_ERR_FAULT; gpc->uhva = KVM_HVA_ERR_BAD; @@ -371,9 +374,9 @@ int kvm_gfn_to_pfn_cache_init(struct kvm *kvm, struct gfn_to_pfn_cache *gpc, } return kvm_gfn_to_pfn_cache_refresh(kvm, gpc, gpa, len); } -EXPORT_SYMBOL_GPL(kvm_gfn_to_pfn_cache_init); +EXPORT_SYMBOL_GPL(kvm_gpc_activate); -void kvm_gfn_to_pfn_cache_destroy(struct kvm *kvm, struct gfn_to_pfn_cache *gpc) +void kvm_gpc_deactivate(struct kvm *kvm, struct gfn_to_pfn_cache *gpc) { if (gpc->active) { spin_lock(&kvm->gpc_lock); @@ -384,4 +387,4 @@ void kvm_gfn_to_pfn_cache_destroy(struct kvm *kvm, struct gfn_to_pfn_cache *gpc) gpc->active = false; } } -EXPORT_SYMBOL_GPL(kvm_gfn_to_pfn_cache_destroy); +EXPORT_SYMBOL_GPL(kvm_gpc_deactivate); |