KVM: pfncache: remove KVM_GUEST_USES_PFN usage
As noted in [1] the KVM_GUEST_USES_PFN usage flag is never set by any callers of kvm_gpc_init(), and for good reason: the implementation is incomplete/broken. And it's not clear that there will ever be a user of KVM_GUEST_USES_PFN, as coordinating vCPUs with mmu_notifier events is non-trivial. Remove KVM_GUEST_USES_PFN and all related code, e.g. dropping KVM_GUEST_USES_PFN also makes the 'vcpu' argument redundant, to avoid having to reason about broken code as __kvm_gpc_refresh() evolves. Moreover, all existing callers specify KVM_HOST_USES_PFN so the usage check in hva_to_pfn_retry() and hence the 'usage' argument to kvm_gpc_init() are also redundant. [1] https://lore.kernel.org/all/ZQiR8IpqOZrOpzHC@google.com Signed-off-by: Paul Durrant <pdurrant@amazon.com> Reviewed-by: David Woodhouse <dwmw@amazon.co.uk> Link: https://lore.kernel.org/r/20240215152916.1158-6-paul@xen.org [sean: explicitly call out that guest usage is incomplete] Signed-off-by: Sean Christopherson <seanjc@google.com>
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@ -12056,7 +12056,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
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vcpu->arch.regs_avail = ~0;
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vcpu->arch.regs_dirty = ~0;
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kvm_gpc_init(&vcpu->arch.pv_time, vcpu->kvm, vcpu, KVM_HOST_USES_PFN);
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kvm_gpc_init(&vcpu->arch.pv_time, vcpu->kvm);
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if (!irqchip_in_kernel(vcpu->kvm) || kvm_vcpu_is_reset_bsp(vcpu))
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vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
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@ -2108,14 +2108,10 @@ void kvm_xen_init_vcpu(struct kvm_vcpu *vcpu)
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timer_setup(&vcpu->arch.xen.poll_timer, cancel_evtchn_poll, 0);
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kvm_gpc_init(&vcpu->arch.xen.runstate_cache, vcpu->kvm, NULL,
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KVM_HOST_USES_PFN);
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kvm_gpc_init(&vcpu->arch.xen.runstate2_cache, vcpu->kvm, NULL,
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KVM_HOST_USES_PFN);
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kvm_gpc_init(&vcpu->arch.xen.vcpu_info_cache, vcpu->kvm, NULL,
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KVM_HOST_USES_PFN);
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kvm_gpc_init(&vcpu->arch.xen.vcpu_time_info_cache, vcpu->kvm, NULL,
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KVM_HOST_USES_PFN);
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kvm_gpc_init(&vcpu->arch.xen.runstate_cache, vcpu->kvm);
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kvm_gpc_init(&vcpu->arch.xen.runstate2_cache, vcpu->kvm);
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kvm_gpc_init(&vcpu->arch.xen.vcpu_info_cache, vcpu->kvm);
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kvm_gpc_init(&vcpu->arch.xen.vcpu_time_info_cache, vcpu->kvm);
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}
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void kvm_xen_destroy_vcpu(struct kvm_vcpu *vcpu)
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@ -2158,7 +2154,7 @@ void kvm_xen_init_vm(struct kvm *kvm)
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{
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mutex_init(&kvm->arch.xen.xen_lock);
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idr_init(&kvm->arch.xen.evtchn_ports);
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kvm_gpc_init(&kvm->arch.xen.shinfo_cache, kvm, NULL, KVM_HOST_USES_PFN);
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kvm_gpc_init(&kvm->arch.xen.shinfo_cache, kvm);
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}
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void kvm_xen_destroy_vm(struct kvm *kvm)
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@ -1319,21 +1319,12 @@ void kvm_vcpu_mark_page_dirty(struct kvm_vcpu *vcpu, gfn_t gfn);
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*
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* @gpc: struct gfn_to_pfn_cache object.
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* @kvm: pointer to kvm instance.
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* @vcpu: vCPU to be used for marking pages dirty and to be woken on
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* invalidation.
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* @usage: indicates if the resulting host physical PFN is used while
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* the @vcpu is IN_GUEST_MODE (in which case invalidation of
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* the cache from MMU notifiers---but not for KVM memslot
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* changes!---will also force @vcpu to exit the guest and
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* refresh the cache); and/or if the PFN used directly
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* by KVM (and thus needs a kernel virtual mapping).
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*
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* This sets up a gfn_to_pfn_cache by initializing locks and assigning the
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* immutable attributes. Note, the cache must be zero-allocated (or zeroed by
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* the caller before init).
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*/
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void kvm_gpc_init(struct gfn_to_pfn_cache *gpc, struct kvm *kvm,
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struct kvm_vcpu *vcpu, enum pfn_cache_usage usage);
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void kvm_gpc_init(struct gfn_to_pfn_cache *gpc, struct kvm *kvm);
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/**
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* kvm_gpc_activate - prepare a cached kernel mapping and HPA for a given guest
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@ -49,12 +49,6 @@ typedef u64 hfn_t;
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typedef hfn_t kvm_pfn_t;
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enum pfn_cache_usage {
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KVM_GUEST_USES_PFN = BIT(0),
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KVM_HOST_USES_PFN = BIT(1),
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KVM_GUEST_AND_HOST_USE_PFN = KVM_GUEST_USES_PFN | KVM_HOST_USES_PFN,
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};
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struct gfn_to_hva_cache {
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u64 generation;
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gpa_t gpa;
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@ -69,13 +63,11 @@ struct gfn_to_pfn_cache {
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unsigned long uhva;
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struct kvm_memory_slot *memslot;
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struct kvm *kvm;
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struct kvm_vcpu *vcpu;
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struct list_head list;
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rwlock_t lock;
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struct mutex refresh_lock;
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void *khva;
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kvm_pfn_t pfn;
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enum pfn_cache_usage usage;
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bool active;
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bool valid;
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};
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@ -25,9 +25,7 @@
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void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm, unsigned long start,
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unsigned long end, bool may_block)
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{
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DECLARE_BITMAP(vcpu_bitmap, KVM_MAX_VCPUS);
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struct gfn_to_pfn_cache *gpc;
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bool evict_vcpus = false;
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spin_lock(&kvm->gpc_lock);
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list_for_each_entry(gpc, &kvm->gpc_list, list) {
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@ -37,43 +35,10 @@ void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm, unsigned long start,
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if (gpc->valid && !is_error_noslot_pfn(gpc->pfn) &&
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gpc->uhva >= start && gpc->uhva < end) {
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gpc->valid = false;
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/*
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* If a guest vCPU could be using the physical address,
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* it needs to be forced out of guest mode.
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*/
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if (gpc->usage & KVM_GUEST_USES_PFN) {
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if (!evict_vcpus) {
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evict_vcpus = true;
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bitmap_zero(vcpu_bitmap, KVM_MAX_VCPUS);
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}
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__set_bit(gpc->vcpu->vcpu_idx, vcpu_bitmap);
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}
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}
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write_unlock_irq(&gpc->lock);
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}
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spin_unlock(&kvm->gpc_lock);
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if (evict_vcpus) {
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/*
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* KVM needs to ensure the vCPU is fully out of guest context
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* before allowing the invalidation to continue.
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*/
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unsigned int req = KVM_REQ_OUTSIDE_GUEST_MODE;
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bool called;
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/*
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* If the OOM reaper is active, then all vCPUs should have
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* been stopped already, so perform the request without
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* KVM_REQUEST_WAIT and be sad if any needed to be IPI'd.
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*/
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if (!may_block)
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req &= ~KVM_REQUEST_WAIT;
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called = kvm_make_vcpus_request_mask(kvm, req, vcpu_bitmap);
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WARN_ON_ONCE(called && !may_block);
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}
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}
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bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, unsigned long len)
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@ -206,16 +171,14 @@ static kvm_pfn_t hva_to_pfn_retry(struct gfn_to_pfn_cache *gpc)
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* pfn. Note, kmap() and memremap() can both sleep, so this
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* too must be done outside of gpc->lock!
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*/
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if (gpc->usage & KVM_HOST_USES_PFN) {
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if (new_pfn == gpc->pfn)
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new_khva = old_khva;
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else
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new_khva = gpc_map(new_pfn);
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if (new_pfn == gpc->pfn)
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new_khva = old_khva;
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else
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new_khva = gpc_map(new_pfn);
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if (!new_khva) {
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kvm_release_pfn_clean(new_pfn);
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goto out_error;
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}
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if (!new_khva) {
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kvm_release_pfn_clean(new_pfn);
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goto out_error;
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}
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write_lock_irq(&gpc->lock);
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@ -346,18 +309,12 @@ int kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, unsigned long len)
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return __kvm_gpc_refresh(gpc, gpc->gpa, len);
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}
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void kvm_gpc_init(struct gfn_to_pfn_cache *gpc, struct kvm *kvm,
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struct kvm_vcpu *vcpu, enum pfn_cache_usage usage)
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void kvm_gpc_init(struct gfn_to_pfn_cache *gpc, struct kvm *kvm)
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{
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WARN_ON_ONCE(!usage || (usage & KVM_GUEST_AND_HOST_USE_PFN) != usage);
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WARN_ON_ONCE((usage & KVM_GUEST_USES_PFN) && !vcpu);
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rwlock_init(&gpc->lock);
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mutex_init(&gpc->refresh_lock);
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gpc->kvm = kvm;
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gpc->vcpu = vcpu;
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gpc->usage = usage;
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gpc->pfn = KVM_PFN_ERR_FAULT;
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gpc->uhva = KVM_HVA_ERR_BAD;
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}
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