KVM: Drop @gpa from exported gfn=>pfn cache check() and refresh() helpers
Drop the @gpa param from the exported check()+refresh() helpers and limit changing the cache's GPA to the activate path. All external users just feed in gpc->gpa, i.e. this is a fancy nop. Allowing users to change the GPA at check()+refresh() is dangerous as those helpers explicitly allow concurrent calls, e.g. KVM could get into a livelock scenario. It's also unclear as to what the expected behavior should be if multiple tasks attempt to refresh with different GPAs. Signed-off-by: Sean Christopherson <seanjc@google.com> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
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5762cb1023
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@ -3035,12 +3035,10 @@ static void kvm_setup_guest_pvclock(struct kvm_vcpu *v,
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unsigned long flags;
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read_lock_irqsave(&gpc->lock, flags);
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while (!kvm_gpc_check(gpc, gpc->gpa,
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offset + sizeof(*guest_hv_clock))) {
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while (!kvm_gpc_check(gpc, offset + sizeof(*guest_hv_clock))) {
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read_unlock_irqrestore(&gpc->lock, flags);
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if (kvm_gpc_refresh(gpc, gpc->gpa,
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offset + sizeof(*guest_hv_clock)))
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if (kvm_gpc_refresh(gpc, offset + sizeof(*guest_hv_clock)))
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return;
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read_lock_irqsave(&gpc->lock, flags);
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@ -272,14 +272,14 @@ static void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, bool atomic)
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* gfn_to_pfn caches that cover the region.
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*/
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read_lock_irqsave(&gpc1->lock, flags);
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while (!kvm_gpc_check(gpc1, gpc1->gpa, user_len1)) {
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while (!kvm_gpc_check(gpc1, user_len1)) {
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read_unlock_irqrestore(&gpc1->lock, flags);
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/* When invoked from kvm_sched_out() we cannot sleep */
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if (atomic)
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return;
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if (kvm_gpc_refresh(gpc1, gpc1->gpa, user_len1))
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if (kvm_gpc_refresh(gpc1, user_len1))
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return;
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read_lock_irqsave(&gpc1->lock, flags);
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@ -308,7 +308,7 @@ static void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, bool atomic)
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*/
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read_lock(&gpc2->lock);
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if (!kvm_gpc_check(gpc2, gpc2->gpa, user_len2)) {
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if (!kvm_gpc_check(gpc2, user_len2)) {
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read_unlock(&gpc2->lock);
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read_unlock_irqrestore(&gpc1->lock, flags);
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@ -488,10 +488,10 @@ void kvm_xen_inject_pending_events(struct kvm_vcpu *v)
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* little more honest about it.
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*/
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read_lock_irqsave(&gpc->lock, flags);
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while (!kvm_gpc_check(gpc, gpc->gpa, sizeof(struct vcpu_info))) {
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while (!kvm_gpc_check(gpc, sizeof(struct vcpu_info))) {
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read_unlock_irqrestore(&gpc->lock, flags);
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if (kvm_gpc_refresh(gpc, gpc->gpa, sizeof(struct vcpu_info)))
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if (kvm_gpc_refresh(gpc, sizeof(struct vcpu_info)))
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return;
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read_lock_irqsave(&gpc->lock, flags);
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@ -551,7 +551,7 @@ int __kvm_xen_has_interrupt(struct kvm_vcpu *v)
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sizeof_field(struct compat_vcpu_info, evtchn_upcall_pending));
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read_lock_irqsave(&gpc->lock, flags);
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while (!kvm_gpc_check(gpc, gpc->gpa, sizeof(struct vcpu_info))) {
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while (!kvm_gpc_check(gpc, sizeof(struct vcpu_info))) {
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read_unlock_irqrestore(&gpc->lock, flags);
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/*
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@ -565,7 +565,7 @@ int __kvm_xen_has_interrupt(struct kvm_vcpu *v)
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if (in_atomic() || !task_is_running(current))
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return 1;
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if (kvm_gpc_refresh(gpc, gpc->gpa, sizeof(struct vcpu_info))) {
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if (kvm_gpc_refresh(gpc, sizeof(struct vcpu_info))) {
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/*
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* If this failed, userspace has screwed up the
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* vcpu_info mapping. No interrupts for you.
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@ -1154,7 +1154,7 @@ static bool wait_pending_event(struct kvm_vcpu *vcpu, int nr_ports,
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read_lock_irqsave(&gpc->lock, flags);
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idx = srcu_read_lock(&kvm->srcu);
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if (!kvm_gpc_check(gpc, gpc->gpa, PAGE_SIZE))
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if (!kvm_gpc_check(gpc, PAGE_SIZE))
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goto out_rcu;
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ret = false;
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@ -1576,7 +1576,7 @@ int kvm_xen_set_evtchn_fast(struct kvm_xen_evtchn *xe, struct kvm *kvm)
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idx = srcu_read_lock(&kvm->srcu);
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read_lock_irqsave(&gpc->lock, flags);
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if (!kvm_gpc_check(gpc, gpc->gpa, PAGE_SIZE))
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if (!kvm_gpc_check(gpc, PAGE_SIZE))
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goto out_rcu;
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if (IS_ENABLED(CONFIG_64BIT) && kvm->arch.xen.long_mode) {
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@ -1610,7 +1610,7 @@ int kvm_xen_set_evtchn_fast(struct kvm_xen_evtchn *xe, struct kvm *kvm)
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gpc = &vcpu->arch.xen.vcpu_info_cache;
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read_lock_irqsave(&gpc->lock, flags);
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if (!kvm_gpc_check(gpc, gpc->gpa, sizeof(struct vcpu_info))) {
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if (!kvm_gpc_check(gpc, sizeof(struct vcpu_info))) {
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/*
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* Could not access the vcpu_info. Set the bit in-kernel
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* and prod the vCPU to deliver it for itself.
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@ -1708,7 +1708,7 @@ static int kvm_xen_set_evtchn(struct kvm_xen_evtchn *xe, struct kvm *kvm)
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break;
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idx = srcu_read_lock(&kvm->srcu);
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rc = kvm_gpc_refresh(gpc, gpc->gpa, PAGE_SIZE);
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rc = kvm_gpc_refresh(gpc, PAGE_SIZE);
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srcu_read_unlock(&kvm->srcu, idx);
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} while(!rc);
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@ -1299,7 +1299,6 @@ int kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len)
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* kvm_gpc_check - check validity of a gfn_to_pfn_cache.
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*
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* @gpc: struct gfn_to_pfn_cache object.
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* @gpa: current guest physical address to map.
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* @len: sanity check; the range being access must fit a single page.
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*
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* @return: %true if the cache is still valid and the address matches.
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@ -1312,15 +1311,14 @@ int kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len)
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* Callers in IN_GUEST_MODE may do so without locking, although they should
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* still hold a read lock on kvm->scru for the memslot checks.
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*/
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bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len);
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bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, unsigned long len);
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/**
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* kvm_gpc_refresh - update a previously initialized cache.
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*
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* @gpc: struct gfn_to_pfn_cache object.
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* @gpa: updated guest physical address to map.
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* @len: sanity check; the range being access must fit a single page.
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*
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* @return: 0 for success.
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* -EINVAL for a mapping which would cross a page boundary.
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* -EFAULT for an untranslatable guest physical address.
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@ -1331,7 +1329,7 @@ bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len);
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* still lock and check the cache status, as this function does not return
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* with the lock still held to permit access.
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*/
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int kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len);
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int kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, unsigned long len);
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/**
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* kvm_gpc_deactivate - deactivate and unlink a gfn_to_pfn_cache.
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@ -76,18 +76,17 @@ void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm, unsigned long start,
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}
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}
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bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len)
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bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, unsigned long len)
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{
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struct kvm_memslots *slots = kvm_memslots(gpc->kvm);
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if (!gpc->active)
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return false;
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if ((gpa & ~PAGE_MASK) + len > PAGE_SIZE)
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if ((gpc->gpa & ~PAGE_MASK) + len > PAGE_SIZE)
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return false;
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if (gpc->gpa != gpa || gpc->generation != slots->generation ||
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kvm_is_error_hva(gpc->uhva))
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if (gpc->generation != slots->generation || kvm_is_error_hva(gpc->uhva))
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return false;
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if (!gpc->valid)
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@ -237,7 +236,8 @@ out_error:
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return -EFAULT;
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}
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int kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len)
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static int __kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa,
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unsigned long len)
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{
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struct kvm_memslots *slots = kvm_memslots(gpc->kvm);
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unsigned long page_offset = gpa & ~PAGE_MASK;
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@ -331,6 +331,11 @@ out_unlock:
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return ret;
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}
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int kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, unsigned long len)
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{
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return __kvm_gpc_refresh(gpc, gpc->gpa, len);
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}
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EXPORT_SYMBOL_GPL(kvm_gpc_refresh);
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void kvm_gpc_init(struct gfn_to_pfn_cache *gpc, struct kvm *kvm,
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@ -371,7 +376,7 @@ int kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len)
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gpc->active = true;
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write_unlock_irq(&gpc->lock);
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}
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return kvm_gpc_refresh(gpc, gpa, len);
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return __kvm_gpc_refresh(gpc, gpa, len);
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}
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EXPORT_SYMBOL_GPL(kvm_gpc_activate);
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