From 8457b98cf214149b947898235e5d6a7b3ca3d1ea Mon Sep 17 00:00:00 2001
From: Dariusz Stojaczyk <dariuszx.stojaczyk@intel.com>
Date: Mon, 8 May 2017 09:42:51 -0700
Subject: [PATCH] vhost: defer setting up new mem table

There is an issue when QEMU sets new memory table just after guest OS
starts booting. Then, if guest OS tries to issue any I/O to device (e.g.
using BIOS INT13h - EDD) it will get stuck because previous addresses of
mmaped memory might change.

To fix this issue, defer using the new mem table until after we receive
the first SET_VRING_ADDR message. SET_VRING_ADDR will be sent by QEMU
when guest OS virtio (e.g. virtio-scsi) driver starts initialization.
At this point it is safe to invalidate the old mem tables because there
will be no more outstanding IO at this point.

Change-Id: I24772be87a8b6c8781868b9b7773317761499748
Signed-off-by: Jim Harris <james.r.harris@intel.com>
Signed-off-by: Dariusz Stojaczyk <dariuszx.stojaczyk@intel.com>
---
 lib/vhost/rte_vhost_17_05/vhost.h      |  4 +++
 lib/vhost/rte_vhost_17_05/vhost_user.c | 35 ++++++++++++++++++++++++--
 2 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/lib/vhost/rte_vhost_17_05/vhost.h b/lib/vhost/rte_vhost_17_05/vhost.h
index ddd8a9c43..fd37f4340 100644
--- a/lib/vhost/rte_vhost_17_05/vhost.h
+++ b/lib/vhost/rte_vhost_17_05/vhost.h
@@ -47,6 +47,7 @@
 #include <rte_ether.h>
 
 #include "rte_vhost.h"
+#include "vhost_user.h"
 
 /* Used to indicate that the device is running on a data core */
 #define VIRTIO_DEV_RUNNING 1
@@ -196,6 +197,9 @@ struct virtio_net {
 	uint32_t		nr_guest_pages;
 	uint32_t		max_guest_pages;
 	struct guest_page       *guest_pages;
+	int                     has_new_mem_table;
+	struct VhostUserMemory  mem_table;
+	int                     mem_table_fds[VHOST_MEMORY_MAX_NREGIONS];
 } __rte_cache_aligned;
 
 
diff --git a/lib/vhost/rte_vhost_17_05/vhost_user.c b/lib/vhost/rte_vhost_17_05/vhost_user.c
index f6bee6ebc..81b9fd90c 100644
--- a/lib/vhost/rte_vhost_17_05/vhost_user.c
+++ b/lib/vhost/rte_vhost_17_05/vhost_user.c
@@ -323,6 +323,8 @@ qva_to_vva(struct virtio_net *dev, uint64_t qva)
 	return 0;
 }
 
+static int vhost_setup_mem_table(struct virtio_net *dev);
+
 /*
  * The virtio device sends us the desc, used and avail ring addresses.
  * This function then converts these to our address space.
@@ -332,6 +334,12 @@ vhost_user_set_vring_addr(struct virtio_net *dev, struct vhost_vring_addr *addr)
 {
 	struct vhost_virtqueue *vq;
 
+	if (dev->has_new_mem_table) {
+		vhost_setup_mem_table(dev);
+		dev->has_new_mem_table = 0;
+	}
+
+
 	if (dev->mem == NULL)
 		return -1;
 
@@ -499,7 +507,30 @@ dump_guest_pages(struct virtio_net *dev)
 static int
 vhost_user_set_mem_table(struct virtio_net *dev, struct VhostUserMsg *pmsg)
 {
-	struct VhostUserMemory memory = pmsg->payload.memory;
+	uint32_t i;
+
+	if (dev->has_new_mem_table) {
+		/*
+		 * The previous mem table was not consumed, so close the
+		 *  file descriptors from that mem table before copying
+		 *  the new one.
+		 */
+		for (i = 0; i < dev->mem_table.nregions; i++) {
+			close(dev->mem_table_fds[i]);
+		}
+	}
+
+	memcpy(&dev->mem_table, &pmsg->payload.memory, sizeof(dev->mem_table));
+	memcpy(dev->mem_table_fds, pmsg->fds, sizeof(dev->mem_table_fds));
+	dev->has_new_mem_table = 1;
+
+	return 0;
+}
+
+ static int
+vhost_setup_mem_table(struct virtio_net *dev)
+{
+	struct VhostUserMemory memory = dev->mem_table;
 	struct rte_vhost_mem_region *reg;
 	void *mmap_addr;
 	uint64_t mmap_size;
@@ -532,7 +563,7 @@ vhost_user_set_mem_table(struct virtio_net *dev, struct VhostUserMsg *pmsg)
 	dev->mem->nregions = memory.nregions;
 
 	for (i = 0; i < memory.nregions; i++) {
-		fd  = pmsg->fds[i];
+		fd  = dev->mem_table_fds[i];
 		reg = &dev->mem->regions[i];
 
 		reg->guest_phys_addr = memory.regions[i].guest_phys_addr;