1 files changed, 143 insertions, 108 deletions

diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c
index 2d6aba677830..4e07112a24c2 100644
--- a/virt/kvm/pfncache.c
+++ b/virt/kvm/pfncache.c
@@ -25,55 +25,36 @@
 void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm, unsigned long start,
 				       unsigned long end, bool may_block)
 {
-	DECLARE_BITMAP(vcpu_bitmap, KVM_MAX_VCPUS);
 	struct gfn_to_pfn_cache *gpc;
-	bool evict_vcpus = false;
 
 	spin_lock(&kvm->gpc_lock);
 	list_for_each_entry(gpc, &kvm->gpc_list, list) {
-		write_lock_irq(&gpc->lock);
+		read_lock_irq(&gpc->lock);
 
 		/* Only a single page so no need to care about length */
 		if (gpc->valid && !is_error_noslot_pfn(gpc->pfn) &&
 		    gpc->uhva >= start && gpc->uhva < end) {
-			gpc->valid = false;
+			read_unlock_irq(&gpc->lock);
 
 			/*
-			 * If a guest vCPU could be using the physical address,
-			 * it needs to be forced out of guest mode.
+			 * There is a small window here where the cache could
+			 * be modified, and invalidation would no longer be
+			 * necessary. Hence check again whether invalidation
+			 * is still necessary once the write lock has been
+			 * acquired.
 			 */
-			if (gpc->usage & KVM_GUEST_USES_PFN) {
-				if (!evict_vcpus) {
-					evict_vcpus = true;
-					bitmap_zero(vcpu_bitmap, KVM_MAX_VCPUS);
-				}
-				__set_bit(gpc->vcpu->vcpu_idx, vcpu_bitmap);
-			}
-		}
-		write_unlock_irq(&gpc->lock);
-	}
-	spin_unlock(&kvm->gpc_lock);
-
-	if (evict_vcpus) {
-		/*
-		 * KVM needs to ensure the vCPU is fully out of guest context
-		 * before allowing the invalidation to continue.
-		 */
-		unsigned int req = KVM_REQ_OUTSIDE_GUEST_MODE;
-		bool called;
 
-		/*
-		 * If the OOM reaper is active, then all vCPUs should have
-		 * been stopped already, so perform the request without
-		 * KVM_REQUEST_WAIT and be sad if any needed to be IPI'd.
-		 */
-		if (!may_block)
-			req &= ~KVM_REQUEST_WAIT;
-
-		called = kvm_make_vcpus_request_mask(kvm, req, vcpu_bitmap);
+			write_lock_irq(&gpc->lock);
+			if (gpc->valid && !is_error_noslot_pfn(gpc->pfn) &&
+			    gpc->uhva >= start && gpc->uhva < end)
+				gpc->valid = false;
+			write_unlock_irq(&gpc->lock);
+			continue;
+		}
 
-		WARN_ON_ONCE(called && !may_block);
+		read_unlock_irq(&gpc->lock);
 	}
+	spin_unlock(&kvm->gpc_lock);
 }
 
 bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, unsigned long len)
@@ -83,10 +64,17 @@ bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, unsigned long len)
 	if (!gpc->active)
 		return false;
 
-	if ((gpc->gpa & ~PAGE_MASK) + len > PAGE_SIZE)
+	/*
+	 * If the page was cached from a memslot, make sure the memslots have
+	 * not been re-configured.
+	 */
+	if (!kvm_is_error_gpa(gpc->gpa) && gpc->generation != slots->generation)
+		return false;
+
+	if (kvm_is_error_hva(gpc->uhva))
 		return false;
 
-	if (gpc->generation != slots->generation || kvm_is_error_hva(gpc->uhva))
+	if (offset_in_page(gpc->uhva) + len > PAGE_SIZE)
 		return false;
 
 	if (!gpc->valid)
@@ -94,19 +82,33 @@ bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, unsigned long len)
 
 	return true;
 }
-EXPORT_SYMBOL_GPL(kvm_gpc_check);
 
-static void gpc_unmap_khva(kvm_pfn_t pfn, void *khva)
+static void *gpc_map(kvm_pfn_t pfn)
 {
-	/* Unmap the old pfn/page if it was mapped before. */
-	if (!is_error_noslot_pfn(pfn) && khva) {
-		if (pfn_valid(pfn))
-			kunmap(pfn_to_page(pfn));
+	if (pfn_valid(pfn))
+		return kmap(pfn_to_page(pfn));
+
 #ifdef CONFIG_HAS_IOMEM
-		else
-			memunmap(khva);
+	return memremap(pfn_to_hpa(pfn), PAGE_SIZE, MEMREMAP_WB);
+#else
+	return NULL;
 #endif
+}
+
+static void gpc_unmap(kvm_pfn_t pfn, void *khva)
+{
+	/* Unmap the old pfn/page if it was mapped before. */
+	if (is_error_noslot_pfn(pfn) || !khva)
+		return;
+
+	if (pfn_valid(pfn)) {
+		kunmap(pfn_to_page(pfn));
+		return;
 	}
+
+#ifdef CONFIG_HAS_IOMEM
+	memunmap(khva);
+#endif
 }
 
 static inline bool mmu_notifier_retry_cache(struct kvm *kvm, unsigned long mmu_seq)
@@ -140,7 +142,7 @@ static inline bool mmu_notifier_retry_cache(struct kvm *kvm, unsigned long mmu_s
 static kvm_pfn_t hva_to_pfn_retry(struct gfn_to_pfn_cache *gpc)
 {
 	/* Note, the new page offset may be different than the old! */
-	void *old_khva = gpc->khva - offset_in_page(gpc->khva);
+	void *old_khva = (void *)PAGE_ALIGN_DOWN((uintptr_t)gpc->khva);
 	kvm_pfn_t new_pfn = KVM_PFN_ERR_FAULT;
 	void *new_khva = NULL;
 	unsigned long mmu_seq;
@@ -175,7 +177,7 @@ static kvm_pfn_t hva_to_pfn_retry(struct gfn_to_pfn_cache *gpc)
 			 * the existing mapping and didn't create a new one.
 			 */
 			if (new_khva != old_khva)
-				gpc_unmap_khva(new_pfn, new_khva);
+				gpc_unmap(new_pfn, new_khva);
 
 			kvm_release_pfn_clean(new_pfn);
 
@@ -192,20 +194,14 @@ static kvm_pfn_t hva_to_pfn_retry(struct gfn_to_pfn_cache *gpc)
 		 * pfn.  Note, kmap() and memremap() can both sleep, so this
 		 * too must be done outside of gpc->lock!
 		 */
-		if (gpc->usage & KVM_HOST_USES_PFN) {
-			if (new_pfn == gpc->pfn) {
-				new_khva = old_khva;
-			} else if (pfn_valid(new_pfn)) {
-				new_khva = kmap(pfn_to_page(new_pfn));
-#ifdef CONFIG_HAS_IOMEM
-			} else {
-				new_khva = memremap(pfn_to_hpa(new_pfn), PAGE_SIZE, MEMREMAP_WB);
-#endif
-			}
-			if (!new_khva) {
-				kvm_release_pfn_clean(new_pfn);
-				goto out_error;
-			}
+		if (new_pfn == gpc->pfn)
+			new_khva = old_khva;
+		else
+			new_khva = gpc_map(new_pfn);
+
+		if (!new_khva) {
+			kvm_release_pfn_clean(new_pfn);
+			goto out_error;
 		}
 
 		write_lock_irq(&gpc->lock);
@@ -219,7 +215,7 @@ static kvm_pfn_t hva_to_pfn_retry(struct gfn_to_pfn_cache *gpc)
 
 	gpc->valid = true;
 	gpc->pfn = new_pfn;
-	gpc->khva = new_khva + (gpc->gpa & ~PAGE_MASK);
+	gpc->khva = new_khva + offset_in_page(gpc->uhva);
 
 	/*
 	 * Put the reference to the _new_ pfn.  The pfn is now tracked by the
@@ -236,30 +232,31 @@ out_error:
 	return -EFAULT;
 }
 
-static int __kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa,
+static int __kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long uhva,
 			     unsigned long len)
 {
-	struct kvm_memslots *slots = kvm_memslots(gpc->kvm);
-	unsigned long page_offset = gpa & ~PAGE_MASK;
+	unsigned long page_offset;
 	bool unmap_old = false;
 	unsigned long old_uhva;
 	kvm_pfn_t old_pfn;
+	bool hva_change = false;
 	void *old_khva;
 	int ret;
 
+	/* Either gpa or uhva must be valid, but not both */
+	if (WARN_ON_ONCE(kvm_is_error_gpa(gpa) == kvm_is_error_hva(uhva)))
+		return -EINVAL;
+
 	/*
-	 * If must fit within a single page. The 'len' argument is
-	 * only to enforce that.
+	 * The cached acces must fit within a single page. The 'len' argument
+	 * exists only to enforce that.
 	 */
+	page_offset = kvm_is_error_gpa(gpa) ? offset_in_page(uhva) :
+					      offset_in_page(gpa);
 	if (page_offset + len > PAGE_SIZE)
 		return -EINVAL;
 
-	/*
-	 * If another task is refreshing the cache, wait for it to complete.
-	 * There is no guarantee that concurrent refreshes will see the same
-	 * gpa, memslots generation, etc..., so they must be fully serialized.
-	 */
-	mutex_lock(&gpc->refresh_lock);
+	lockdep_assert_held(&gpc->refresh_lock);
 
 	write_lock_irq(&gpc->lock);
 
@@ -269,30 +266,52 @@ static int __kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa,
 	}
 
 	old_pfn = gpc->pfn;
-	old_khva = gpc->khva - offset_in_page(gpc->khva);
-	old_uhva = gpc->uhva;
-
-	/* If the userspace HVA is invalid, refresh that first */
-	if (gpc->gpa != gpa || gpc->generation != slots->generation ||
-	    kvm_is_error_hva(gpc->uhva)) {
-		gfn_t gfn = gpa_to_gfn(gpa);
-
-		gpc->gpa = gpa;
-		gpc->generation = slots->generation;
-		gpc->memslot = __gfn_to_memslot(slots, gfn);
-		gpc->uhva = gfn_to_hva_memslot(gpc->memslot, gfn);
-
-		if (kvm_is_error_hva(gpc->uhva)) {
-			ret = -EFAULT;
-			goto out;
+	old_khva = (void *)PAGE_ALIGN_DOWN((uintptr_t)gpc->khva);
+	old_uhva = PAGE_ALIGN_DOWN(gpc->uhva);
+
+	if (kvm_is_error_gpa(gpa)) {
+		gpc->gpa = INVALID_GPA;
+		gpc->memslot = NULL;
+		gpc->uhva = PAGE_ALIGN_DOWN(uhva);
+
+		if (gpc->uhva != old_uhva)
+			hva_change = true;
+	} else {
+		struct kvm_memslots *slots = kvm_memslots(gpc->kvm);
+
+		if (gpc->gpa != gpa || gpc->generation != slots->generation ||
+		    kvm_is_error_hva(gpc->uhva)) {
+			gfn_t gfn = gpa_to_gfn(gpa);
+
+			gpc->gpa = gpa;
+			gpc->generation = slots->generation;
+			gpc->memslot = __gfn_to_memslot(slots, gfn);
+			gpc->uhva = gfn_to_hva_memslot(gpc->memslot, gfn);
+
+			if (kvm_is_error_hva(gpc->uhva)) {
+				ret = -EFAULT;
+				goto out;
+			}
+
+			/*
+			 * Even if the GPA and/or the memslot generation changed, the
+			 * HVA may still be the same.
+			 */
+			if (gpc->uhva != old_uhva)
+				hva_change = true;
+		} else {
+			gpc->uhva = old_uhva;
 		}
 	}
 
+	/* Note: the offset must be correct before calling hva_to_pfn_retry() */
+	gpc->uhva += page_offset;
+
 	/*
 	 * If the userspace HVA changed or the PFN was already invalid,
 	 * drop the lock and do the HVA to PFN lookup again.
 	 */
-	if (!gpc->valid || old_uhva != gpc->uhva) {
+	if (!gpc->valid || hva_change) {
 		ret = hva_to_pfn_retry(gpc);
 	} else {
 		/*
@@ -323,41 +342,47 @@ static int __kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa,
 out_unlock:
 	write_unlock_irq(&gpc->lock);
 
-	mutex_unlock(&gpc->refresh_lock);
-
 	if (unmap_old)
-		gpc_unmap_khva(old_pfn, old_khva);
+		gpc_unmap(old_pfn, old_khva);
 
 	return ret;
 }
 
 int kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, unsigned long len)
 {
-	return __kvm_gpc_refresh(gpc, gpc->gpa, len);
+	unsigned long uhva;
+
+	guard(mutex)(&gpc->refresh_lock);
+
+	/*
+	 * If the GPA is valid then ignore the HVA, as a cache can be GPA-based
+	 * or HVA-based, not both.  For GPA-based caches, the HVA will be
+	 * recomputed during refresh if necessary.
+	 */
+	uhva = kvm_is_error_gpa(gpc->gpa) ? gpc->uhva : KVM_HVA_ERR_BAD;
+
+	return __kvm_gpc_refresh(gpc, gpc->gpa, uhva, len);
 }
-EXPORT_SYMBOL_GPL(kvm_gpc_refresh);
 
-void kvm_gpc_init(struct gfn_to_pfn_cache *gpc, struct kvm *kvm,
-		  struct kvm_vcpu *vcpu, enum pfn_cache_usage usage)
+void kvm_gpc_init(struct gfn_to_pfn_cache *gpc, struct kvm *kvm)
 {
-	WARN_ON_ONCE(!usage || (usage & KVM_GUEST_AND_HOST_USE_PFN) != usage);
-	WARN_ON_ONCE((usage & KVM_GUEST_USES_PFN) && !vcpu);
-
 	rwlock_init(&gpc->lock);
 	mutex_init(&gpc->refresh_lock);
 
 	gpc->kvm = kvm;
-	gpc->vcpu = vcpu;
-	gpc->usage = usage;
 	gpc->pfn = KVM_PFN_ERR_FAULT;
+	gpc->gpa = INVALID_GPA;
 	gpc->uhva = KVM_HVA_ERR_BAD;
+	gpc->active = gpc->valid = false;
 }
-EXPORT_SYMBOL_GPL(kvm_gpc_init);
 
-int kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len)
+static int __kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long uhva,
+			      unsigned long len)
 {
 	struct kvm *kvm = gpc->kvm;
 
+	guard(mutex)(&gpc->refresh_lock);
+
 	if (!gpc->active) {
 		if (KVM_BUG_ON(gpc->valid, kvm))
 			return -EIO;
@@ -375,9 +400,18 @@ int kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len)
 		gpc->active = true;
 		write_unlock_irq(&gpc->lock);
 	}
-	return __kvm_gpc_refresh(gpc, gpa, len);
+	return __kvm_gpc_refresh(gpc, gpa, uhva, len);
+}
+
+int kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len)
+{
+	return __kvm_gpc_activate(gpc, gpa, KVM_HVA_ERR_BAD, len);
+}
+
+int kvm_gpc_activate_hva(struct gfn_to_pfn_cache *gpc, unsigned long uhva, unsigned long len)
+{
+	return __kvm_gpc_activate(gpc, INVALID_GPA, uhva, len);
 }
-EXPORT_SYMBOL_GPL(kvm_gpc_activate);
 
 void kvm_gpc_deactivate(struct gfn_to_pfn_cache *gpc)
 {
@@ -385,6 +419,8 @@ void kvm_gpc_deactivate(struct gfn_to_pfn_cache *gpc)
 	kvm_pfn_t old_pfn;
 	void *old_khva;
 
+	guard(mutex)(&gpc->refresh_lock);
+
 	if (gpc->active) {
 		/*
 		 * Deactivate the cache before removing it from the list, KVM
@@ -412,7 +448,6 @@ void kvm_gpc_deactivate(struct gfn_to_pfn_cache *gpc)
 		list_del(&gpc->list);
 		spin_unlock(&kvm->gpc_lock);
 
-		gpc_unmap_khva(old_pfn, old_khva);
+		gpc_unmap(old_pfn, old_khva);
 	}
 }
-EXPORT_SYMBOL_GPL(kvm_gpc_deactivate);