[Qemu-devel] [PATCH] vhost-user: fix VHOST_USER_SET_MEM_TABLE

[Damjan Marion]

Old code was affected by memory gaps which
resulted in buffer pointers pointing to
address outside of the mapped regions.

Signed-off-by: Damjan Marion <address@hidden>
---
 docs/specs/vhost-user.txt |  7 ++++---
 exec.c                    |  7 +++++++
 hw/virtio/vhost-user.c    | 22 +++++++++++++---------
 include/exec/ram_addr.h   |  1 +
 4 files changed, 25 insertions(+), 12 deletions(-)

diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt
index 2641390..c108d07 100644
--- a/docs/specs/vhost-user.txt
+++ b/docs/specs/vhost-user.txt
@@ -78,13 +78,14 @@ Depending on the request type, payload can be:
    Padding: 32-bit
 
    A region is:
-   ---------------------------------------
-   | guest address | size | user address |
-   ---------------------------------------
+   -----------------------------------------------------------
+   | guest address | size | user address | shared mem offset |
+   -----------------------------------------------------------
 
    Guest address: a 64-bit guest address of the region
    Size: a 64-bit size
    User address: a 64-bit user address
+   Shared mem offset: 64-bit offset where region is located in the shared 
memory
 
 
 In QEMU the vhost-user message is implemented with the following struct:
diff --git a/exec.c b/exec.c
index c849405..a94c583 100644
--- a/exec.c
+++ b/exec.c
@@ -1456,6 +1456,13 @@ int qemu_get_ram_fd(ram_addr_t addr)
     return block->fd;
 }
 
+void *qemu_get_ram_block_host_ptr(ram_addr_t addr)
+{
+    RAMBlock *block = qemu_get_ram_block(addr);
+
+    return block->host;
+}
+
 /* Return a host pointer to ram allocated with qemu_ram_alloc.
    With the exception of the softmmu code in this file, this should
    only be used for local memory (e.g. video ram) that the device owns,
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 0df6a93..0cef2d3 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -14,6 +14,7 @@
 #include "sysemu/kvm.h"
 #include "qemu/error-report.h"
 #include "qemu/sockets.h"
+#include "exec/ram_addr.h"
 
 #include <fcntl.h>
 #include <unistd.h>
@@ -47,6 +48,7 @@ typedef struct VhostUserMemoryRegion {
     uint64_t guest_phys_addr;
     uint64_t memory_size;
     uint64_t userspace_addr;
+    uint64_t shm_offset;
 } VhostUserMemoryRegion;
 
 typedef struct VhostUserMemory {
@@ -183,10 +185,10 @@ static int vhost_user_call(struct vhost_dev *dev, 
unsigned long int request,
 {
     VhostUserMsg msg;
     VhostUserRequest msg_request;
-    RAMBlock *block = 0;
     struct vhost_vring_file *file = 0;
     int need_reply = 0;
     int fds[VHOST_MEMORY_MAX_NREGIONS];
+    int i, fd;
     size_t fd_num = 0;
 
     assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
@@ -212,14 +214,16 @@ static int vhost_user_call(struct vhost_dev *dev, 
unsigned long int request,
         break;
 
     case VHOST_SET_MEM_TABLE:
-        QTAILQ_FOREACH(block, &ram_list.blocks, next)
-        {
-            if (block->fd > 0) {
-                msg.memory.regions[fd_num].userspace_addr =
-                    (uintptr_t) block->host;
-                msg.memory.regions[fd_num].memory_size = block->length;
-                msg.memory.regions[fd_num].guest_phys_addr = block->offset;
-                fds[fd_num++] = block->fd;
+        for (i = 0; i < dev->mem->nregions; ++i) {
+            struct vhost_memory_region *reg = dev->mem->regions + i;
+            fd = qemu_get_ram_fd(reg->guest_phys_addr);
+            if (fd > 0) {
+                msg.memory.regions[fd_num].userspace_addr = 
reg->userspace_addr;
+                msg.memory.regions[fd_num].memory_size  = reg->memory_size;
+                msg.memory.regions[fd_num].guest_phys_addr = 
reg->guest_phys_addr;
+                msg.memory.regions[fd_num].shm_offset = reg->userspace_addr -
+                    (ram_addr_t) 
qemu_get_ram_block_host_ptr(reg->guest_phys_addr);
+                fds[fd_num++] = fd;
             }
         }
 
diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
index 55ca676..e9eb831 100644
--- a/include/exec/ram_addr.h
+++ b/include/exec/ram_addr.h
@@ -29,6 +29,7 @@ ram_addr_t qemu_ram_alloc_from_ptr(ram_addr_t size, void 
*host,
                                    MemoryRegion *mr);
 ram_addr_t qemu_ram_alloc(ram_addr_t size, MemoryRegion *mr);
 int qemu_get_ram_fd(ram_addr_t addr);
+void *qemu_get_ram_block_host_ptr(ram_addr_t addr);
 void *qemu_get_ram_ptr(ram_addr_t addr);
 void qemu_ram_free(ram_addr_t addr);
 void qemu_ram_free_from_ptr(ram_addr_t addr);
-- 
1.9.1