vhost: export APIs for live migration support

Export few APIs for the vhost-user driver to log the guest memory writes,
which is a must for live migration support.

This patch basically moves vhost_log_write() and vhost_log_used_vring()
into vhost.h and then add an wrapper (the public API) to them.

Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

lib/librte_vhost/rte_vhost_version.map

@@ -41,5 +41,7 @@ DPDK_17.05 {
 	rte_vhost_get_vhost_vring;
 	rte_vhost_get_vring_num;
 	rte_vhost_gpa_to_vva;
+	rte_vhost_log_used_vring;
+	rte_vhost_log_write;
 
 } DPDK_16.07;

lib/librte_vhost/rte_virtio_net.h

@@ -132,6 +132,49 @@ rte_vhost_gpa_to_vva(struct rte_vhost_memory *mem, uint64_t gpa)
 	return 0;
 }
 
+#define RTE_VHOST_NEED_LOG(features)	((features) & (1ULL << VHOST_F_LOG_ALL))
+
+/**
+ * Log the memory write start with given address.
+ *
+ * This function only need be invoked when the live migration starts.
+ * Therefore, we won't need call it at all in the most of time. For
+ * making the performance impact be minimum, it's suggested to do a
+ * check before calling it:
+ *
+ *        if (unlikely(RTE_VHOST_NEED_LOG(features)))
+ *                rte_vhost_log_write(vid, addr, len);
+ *
+ * @param vid
+ *  vhost device ID
+ * @param addr
+ *  the starting address for write
+ * @param len
+ *  the length to write
+ */
+void rte_vhost_log_write(int vid, uint64_t addr, uint64_t len);
+
+/**
+ * Log the used ring update start at given offset.
+ *
+ * Same as rte_vhost_log_write, it's suggested to do a check before
+ * calling it:
+ *
+ *        if (unlikely(RTE_VHOST_NEED_LOG(features)))
+ *                rte_vhost_log_used_vring(vid, vring_idx, offset, len);
+ *
+ * @param vid
+ *  vhost device ID
+ * @param vring_idx
+ *  the vring index
+ * @param offset
+ *  the offset inside the used ring
+ * @param len
+ *  the length to write
+ */
+void rte_vhost_log_used_vring(int vid, uint16_t vring_idx,
+			      uint64_t offset, uint64_t len);
+
 int rte_vhost_enable_guest_notification(int vid, uint16_t queue_id, int enable);
 
 /**

lib/librte_vhost/vhost.c

@@ -444,3 +444,34 @@ rte_vhost_enable_guest_notification(int vid, uint16_t queue_id, int enable)
 	dev->virtqueue[queue_id]->used->flags = VRING_USED_F_NO_NOTIFY;
 	return 0;
 }
+
+void
+rte_vhost_log_write(int vid, uint64_t addr, uint64_t len)
+{
+	struct virtio_net *dev = get_device(vid);
+
+	if (dev == NULL)
+		return;
+
+	vhost_log_write(dev, addr, len);
+}
+
+void
+rte_vhost_log_used_vring(int vid, uint16_t vring_idx,
+			 uint64_t offset, uint64_t len)
+{
+	struct virtio_net *dev;
+	struct vhost_virtqueue *vq;
+
+	dev = get_device(vid);
+	if (dev == NULL)
+		return;
+
+	if (vring_idx >= VHOST_MAX_VRING)
+		return;
+	vq = dev->virtqueue[vring_idx];
+	if (!vq)
+		return;
+
+	vhost_log_used_vring(dev, vq, offset, len);
+}

lib/librte_vhost/vhost.h

@@ -198,6 +198,44 @@ struct virtio_net {
 	struct guest_page       *guest_pages;
 } __rte_cache_aligned;
 
+
+#define VHOST_LOG_PAGE	4096
+
+static inline void __attribute__((always_inline))
+vhost_log_page(uint8_t *log_base, uint64_t page)
+{
+	log_base[page / 8] |= 1 << (page % 8);
+}
+
+static inline void __attribute__((always_inline))
+vhost_log_write(struct virtio_net *dev, uint64_t addr, uint64_t len)
+{
+	uint64_t page;
+
+	if (likely(((dev->features & (1ULL << VHOST_F_LOG_ALL)) == 0) ||
+		   !dev->log_base || !len))
+		return;
+
+	if (unlikely(dev->log_size <= ((addr + len - 1) / VHOST_LOG_PAGE / 8)))
+		return;
+
+	/* To make sure guest memory updates are committed before logging */
+	rte_smp_wmb();
+
+	page = addr / VHOST_LOG_PAGE;
+	while (page * VHOST_LOG_PAGE < addr + len) {
+		vhost_log_page((uint8_t *)(uintptr_t)dev->log_base, page);
+		page += 1;
+	}
+}
+
+static inline void __attribute__((always_inline))
+vhost_log_used_vring(struct virtio_net *dev, struct vhost_virtqueue *vq,
+		     uint64_t offset, uint64_t len)
+{
+	vhost_log_write(dev, vq->log_guest_addr + offset, len);
+}
+
 /* Macros for printing using RTE_LOG */
 #define RTE_LOGTYPE_VHOST_CONFIG RTE_LOGTYPE_USER1
 #define RTE_LOGTYPE_VHOST_DATA   RTE_LOGTYPE_USER1

lib/librte_vhost/virtio_net.c

@@ -48,42 +48,6 @@
 #include "vhost.h"
 
 #define MAX_PKT_BURST 32
-#define VHOST_LOG_PAGE	4096
-
-static inline void __attribute__((always_inline))
-vhost_log_page(uint8_t *log_base, uint64_t page)
-{
-	log_base[page / 8] |= 1 << (page % 8);
-}
-
-static inline void __attribute__((always_inline))
-vhost_log_write(struct virtio_net *dev, uint64_t addr, uint64_t len)
-{
-	uint64_t page;
-
-	if (likely(((dev->features & (1ULL << VHOST_F_LOG_ALL)) == 0) ||
-		   !dev->log_base || !len))
-		return;
-
-	if (unlikely(dev->log_size <= ((addr + len - 1) / VHOST_LOG_PAGE / 8)))
-		return;
-
-	/* To make sure guest memory updates are committed before logging */
-	rte_smp_wmb();
-
-	page = addr / VHOST_LOG_PAGE;
-	while (page * VHOST_LOG_PAGE < addr + len) {
-		vhost_log_page((uint8_t *)(uintptr_t)dev->log_base, page);
-		page += 1;
-	}
-}
-
-static inline void __attribute__((always_inline))
-vhost_log_used_vring(struct virtio_net *dev, struct vhost_virtqueue *vq,
-		     uint64_t offset, uint64_t len)
-{
-	vhost_log_write(dev, vq->log_guest_addr + offset, len);
-}
 
 static bool
 is_valid_virt_queue_idx(uint32_t idx, int is_tx, uint32_t nr_vring)