Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

Pull vhost updates from Michael Tsirkin:
 "virtio, vhost: optimizations, fixes

  Looks like a quiet cycle for vhost/virtio, just a couple of minor
  tweaks. Most notable is automatic interrupt affinity for blk and scsi.
  Hopefully other devices are not far behind"

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  virtio-console: avoid DMA from stack
  vhost: introduce O(1) vq metadata cache
  virtio_scsi: use virtio IRQ affinity
  virtio_blk: use virtio IRQ affinity
  blk-mq: provide a default queue mapping for virtio device
  virtio: provide a method to get the IRQ affinity mask for a virtqueue
  virtio: allow drivers to request IRQ affinity when creating VQs
  virtio_pci: simplify MSI-X setup
  virtio_pci: don't duplicate the msix_enable flag in struct pci_dev
  virtio_pci: use shared interrupts for virtqueues
  virtio_pci: remove struct virtio_pci_vq_info
  vhost: try avoiding avail index access when getting descriptor
  virtio_mmio: expose header to userspace

2 files changed, 140 insertions, 41 deletions

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 4269e621e254..9469364eefd7 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -282,6 +282,22 @@ void vhost_poll_queue(struct vhost_poll *poll)
 }
 EXPORT_SYMBOL_GPL(vhost_poll_queue);
 
+static void __vhost_vq_meta_reset(struct vhost_virtqueue *vq)
+{
+	int j;
+
+	for (j = 0; j < VHOST_NUM_ADDRS; j++)
+		vq->meta_iotlb[j] = NULL;
+}
+
+static void vhost_vq_meta_reset(struct vhost_dev *d)
+{
+	int i;
+
+	for (i = 0; i < d->nvqs; ++i)
+		__vhost_vq_meta_reset(d->vqs[i]);
+}
+
 static void vhost_vq_reset(struct vhost_dev *dev,
 			   struct vhost_virtqueue *vq)
 {
@@ -312,6 +328,7 @@ static void vhost_vq_reset(struct vhost_dev *dev,
 	vq->busyloop_timeout = 0;
 	vq->umem = NULL;
 	vq->iotlb = NULL;
+	__vhost_vq_meta_reset(vq);
 }
 
 static int vhost_worker(void *data)
@@ -691,6 +708,18 @@ static int vq_memory_access_ok(void __user *log_base, struct vhost_umem *umem,
 	return 1;
 }
 
+static inline void __user *vhost_vq_meta_fetch(struct vhost_virtqueue *vq,
+					       u64 addr, unsigned int size,
+					       int type)
+{
+	const struct vhost_umem_node *node = vq->meta_iotlb[type];
+
+	if (!node)
+		return NULL;
+
+	return (void *)(uintptr_t)(node->userspace_addr + addr - node->start);
+}
+
 /* Can we switch to this memory table? */
 /* Caller should have device mutex but not vq mutex */
 static int memory_access_ok(struct vhost_dev *d, struct vhost_umem *umem,
@@ -733,8 +762,14 @@ static int vhost_copy_to_user(struct vhost_virtqueue *vq, void __user *to,
 		 * could be access through iotlb. So -EAGAIN should
 		 * not happen in this case.
 		 */
-		/* TODO: more fast path */
 		struct iov_iter t;
+		void __user *uaddr = vhost_vq_meta_fetch(vq,
+				     (u64)(uintptr_t)to, size,
+				     VHOST_ADDR_DESC);
+
+		if (uaddr)
+			return __copy_to_user(uaddr, from, size);
+
 		ret = translate_desc(vq, (u64)(uintptr_t)to, size, vq->iotlb_iov,
 				     ARRAY_SIZE(vq->iotlb_iov),
 				     VHOST_ACCESS_WO);
@@ -762,8 +797,14 @@ static int vhost_copy_from_user(struct vhost_virtqueue *vq, void *to,
 		 * could be access through iotlb. So -EAGAIN should
 		 * not happen in this case.
 		 */
-		/* TODO: more fast path */
+		void __user *uaddr = vhost_vq_meta_fetch(vq,
+				     (u64)(uintptr_t)from, size,
+				     VHOST_ADDR_DESC);
 		struct iov_iter f;
+
+		if (uaddr)
+			return __copy_from_user(to, uaddr, size);
+
 		ret = translate_desc(vq, (u64)(uintptr_t)from, size, vq->iotlb_iov,
 				     ARRAY_SIZE(vq->iotlb_iov),
 				     VHOST_ACCESS_RO);
@@ -783,17 +824,12 @@ out:
 	return ret;
 }
 
-static void __user *__vhost_get_user(struct vhost_virtqueue *vq,
-				     void __user *addr, unsigned size)
+static void __user *__vhost_get_user_slow(struct vhost_virtqueue *vq,
+					  void __user *addr, unsigned int size,
+					  int type)
 {
 	int ret;
 
-	/* This function should be called after iotlb
-	 * prefetch, which means we're sure that vq
-	 * could be access through iotlb. So -EAGAIN should
-	 * not happen in this case.
-	 */
-	/* TODO: more fast path */
 	ret = translate_desc(vq, (u64)(uintptr_t)addr, size, vq->iotlb_iov,
 			     ARRAY_SIZE(vq->iotlb_iov),
 			     VHOST_ACCESS_RO);
@@ -814,14 +850,32 @@ static void __user *__vhost_get_user(struct vhost_virtqueue *vq,
 	return vq->iotlb_iov[0].iov_base;
 }
 
-#define vhost_put_user(vq, x, ptr) \
+/* This function should be called after iotlb
+ * prefetch, which means we're sure that vq
+ * could be access through iotlb. So -EAGAIN should
+ * not happen in this case.
+ */
+static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq,
+					    void *addr, unsigned int size,
+					    int type)
+{
+	void __user *uaddr = vhost_vq_meta_fetch(vq,
+			     (u64)(uintptr_t)addr, size, type);
+	if (uaddr)
+		return uaddr;
+
+	return __vhost_get_user_slow(vq, addr, size, type);
+}
+
+#define vhost_put_user(vq, x, ptr)		\
 ({ \
 	int ret = -EFAULT; \
 	if (!vq->iotlb) { \
 		ret = __put_user(x, ptr); \
 	} else { \
 		__typeof__(ptr) to = \
-			(__typeof__(ptr)) __vhost_get_user(vq, ptr, sizeof(*ptr)); \
+			(__typeof__(ptr)) __vhost_get_user(vq, ptr,	\
+					  sizeof(*ptr), VHOST_ADDR_USED); \
 		if (to != NULL) \
 			ret = __put_user(x, to); \
 		else \
@@ -830,14 +884,16 @@ static void __user *__vhost_get_user(struct vhost_virtqueue *vq,
 	ret; \
 })
 
-#define vhost_get_user(vq, x, ptr) \
+#define vhost_get_user(vq, x, ptr, type)		\
 ({ \
 	int ret; \
 	if (!vq->iotlb) { \
 		ret = __get_user(x, ptr); \
 	} else { \
 		__typeof__(ptr) from = \
-			(__typeof__(ptr)) __vhost_get_user(vq, ptr, sizeof(*ptr)); \
+			(__typeof__(ptr)) __vhost_get_user(vq, ptr, \
+							   sizeof(*ptr), \
+							   type); \
 		if (from != NULL) \
 			ret = __get_user(x, from); \
 		else \
@@ -846,6 +902,12 @@ static void __user *__vhost_get_user(struct vhost_virtqueue *vq,
 	ret; \
 })
 
+#define vhost_get_avail(vq, x, ptr) \
+	vhost_get_user(vq, x, ptr, VHOST_ADDR_AVAIL)
+
+#define vhost_get_used(vq, x, ptr) \
+	vhost_get_user(vq, x, ptr, VHOST_ADDR_USED)
+
 static void vhost_dev_lock_vqs(struct vhost_dev *d)
 {
 	int i = 0;
@@ -951,6 +1013,7 @@ static int vhost_process_iotlb_msg(struct vhost_dev *dev,
 			ret = -EFAULT;
 			break;
 		}
+		vhost_vq_meta_reset(dev);
 		if (vhost_new_umem_range(dev->iotlb, msg->iova, msg->size,
 					 msg->iova + msg->size - 1,
 					 msg->uaddr, msg->perm)) {
@@ -960,6 +1023,7 @@ static int vhost_process_iotlb_msg(struct vhost_dev *dev,
 		vhost_iotlb_notify_vq(dev, msg);
 		break;
 	case VHOST_IOTLB_INVALIDATE:
+		vhost_vq_meta_reset(dev);
 		vhost_del_umem_range(dev->iotlb, msg->iova,
 				     msg->iova + msg->size - 1);
 		break;
@@ -1103,12 +1167,26 @@ static int vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
 			sizeof *used + num * sizeof *used->ring + s);
 }
 
+static void vhost_vq_meta_update(struct vhost_virtqueue *vq,
+				 const struct vhost_umem_node *node,
+				 int type)
+{
+	int access = (type == VHOST_ADDR_USED) ?
+		     VHOST_ACCESS_WO : VHOST_ACCESS_RO;
+
+	if (likely(node->perm & access))
+		vq->meta_iotlb[type] = node;
+}
+
 static int iotlb_access_ok(struct vhost_virtqueue *vq,
-			   int access, u64 addr, u64 len)
+			   int access, u64 addr, u64 len, int type)
 {
 	const struct vhost_umem_node *node;
 	struct vhost_umem *umem = vq->iotlb;
-	u64 s = 0, size;
+	u64 s = 0, size, orig_addr = addr;
+
+	if (vhost_vq_meta_fetch(vq, addr, len, type))
+		return true;
 
 	while (len > s) {
 		node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
@@ -1125,6 +1203,10 @@ static int iotlb_access_ok(struct vhost_virtqueue *vq,
 		}
 
 		size = node->size - addr + node->start;
+
+		if (orig_addr == addr && size >= len)
+			vhost_vq_meta_update(vq, node, type);
+
 		s += size;
 		addr += size;
 	}
@@ -1141,13 +1223,15 @@ int vq_iotlb_prefetch(struct vhost_virtqueue *vq)
 		return 1;
 
 	return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc,
-			       num * sizeof *vq->desc) &&
+			       num * sizeof(*vq->desc), VHOST_ADDR_DESC) &&
 	       iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->avail,
 			       sizeof *vq->avail +
-			       num * sizeof *vq->avail->ring + s) &&
+			       num * sizeof(*vq->avail->ring) + s,
+			       VHOST_ADDR_AVAIL) &&
 	       iotlb_access_ok(vq, VHOST_ACCESS_WO, (u64)(uintptr_t)vq->used,
 			       sizeof *vq->used +
-			       num * sizeof *vq->used->ring + s);
+			       num * sizeof(*vq->used->ring) + s,
+			       VHOST_ADDR_USED);
 }
 EXPORT_SYMBOL_GPL(vq_iotlb_prefetch);
 
@@ -1728,7 +1812,7 @@ int vhost_vq_init_access(struct vhost_virtqueue *vq)
 		r = -EFAULT;
 		goto err;
 	}
-	r = vhost_get_user(vq, last_used_idx, &vq->used->idx);
+	r = vhost_get_used(vq, last_used_idx, &vq->used->idx);
 	if (r) {
 		vq_err(vq, "Can't access used idx at %p\n",
 		       &vq->used->idx);
@@ -1930,29 +2014,36 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
 
 	/* Check it isn't doing very strange things with descriptor numbers. */
 	last_avail_idx = vq->last_avail_idx;
-	if (unlikely(vhost_get_user(vq, avail_idx, &vq->avail->idx))) {
-		vq_err(vq, "Failed to access avail idx at %p\n",
-		       &vq->avail->idx);
-		return -EFAULT;
-	}
-	vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
 
-	if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
-		vq_err(vq, "Guest moved used index from %u to %u",
-		       last_avail_idx, vq->avail_idx);
-		return -EFAULT;
-	}
+	if (vq->avail_idx == vq->last_avail_idx) {
+		if (unlikely(vhost_get_avail(vq, avail_idx, &vq->avail->idx))) {
+			vq_err(vq, "Failed to access avail idx at %p\n",
+				&vq->avail->idx);
+			return -EFAULT;
+		}
+		vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
 
-	/* If there's nothing new since last we looked, return invalid. */
-	if (vq->avail_idx == last_avail_idx)
-		return vq->num;
+		if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
+			vq_err(vq, "Guest moved used index from %u to %u",
+				last_avail_idx, vq->avail_idx);
+			return -EFAULT;
+		}
+
+		/* If there's nothing new since last we looked, return
+		 * invalid.
+		 */
+		if (vq->avail_idx == last_avail_idx)
+			return vq->num;
 
-	/* Only get avail ring entries after they have been exposed by guest. */
-	smp_rmb();
+		/* Only get avail ring entries after they have been
+		 * exposed by guest.
+		 */
+		smp_rmb();
+	}
 
 	/* Grab the next descriptor number they're advertising, and increment
 	 * the index we've seen. */
-	if (unlikely(vhost_get_user(vq, ring_head,
+	if (unlikely(vhost_get_avail(vq, ring_head,
 		     &vq->avail->ring[last_avail_idx & (vq->num - 1)]))) {
 		vq_err(vq, "Failed to read head: idx %d address %p\n",
 		       last_avail_idx,
@@ -2168,7 +2259,7 @@ static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
 		 * with the barrier that the Guest executes when enabling
 		 * interrupts. */
 		smp_mb();
-		if (vhost_get_user(vq, flags, &vq->avail->flags)) {
+		if (vhost_get_avail(vq, flags, &vq->avail->flags)) {
 			vq_err(vq, "Failed to get flags");
 			return true;
 		}
@@ -2195,7 +2286,7 @@ static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
 	 * interrupts. */
 	smp_mb();
 
-	if (vhost_get_user(vq, event, vhost_used_event(vq))) {
+	if (vhost_get_avail(vq, event, vhost_used_event(vq))) {
 		vq_err(vq, "Failed to get used event idx");
 		return true;
 	}
@@ -2242,7 +2333,7 @@ bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
 	if (vq->avail_idx != vq->last_avail_idx)
 		return false;
 
-	r = vhost_get_user(vq, avail_idx, &vq->avail->idx);
+	r = vhost_get_avail(vq, avail_idx, &vq->avail->idx);
 	if (unlikely(r))
 		return false;
 	vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
@@ -2278,7 +2369,7 @@ bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
 	/* They could have slipped one in as we were doing that: make
 	 * sure it's written, then check again. */
 	smp_mb();
-	r = vhost_get_user(vq, avail_idx, &vq->avail->idx);
+	r = vhost_get_avail(vq, avail_idx, &vq->avail->idx);
 	if (r) {
 		vq_err(vq, "Failed to check avail idx at %p: %d\n",
 		       &vq->avail->idx, r);
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index a9cbbb148f46..f55671d53f28 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -76,6 +76,13 @@ struct vhost_umem {
 	int numem;
 };
 
+enum vhost_uaddr_type {
+	VHOST_ADDR_DESC = 0,
+	VHOST_ADDR_AVAIL = 1,
+	VHOST_ADDR_USED = 2,
+	VHOST_NUM_ADDRS = 3,
+};
+
 /* The virtqueue structure describes a queue attached to a device. */
 struct vhost_virtqueue {
 	struct vhost_dev *dev;
@@ -86,6 +93,7 @@ struct vhost_virtqueue {
 	struct vring_desc __user *desc;
 	struct vring_avail __user *avail;
 	struct vring_used __user *used;
+	const struct vhost_umem_node *meta_iotlb[VHOST_NUM_ADDRS];
 	struct file *kick;
 	struct file *call;
 	struct file *error;