@@ -205,10 +205,17 @@ ivshmem_client_connect(IvshmemClient *client)
goto err_close;
}
- /* first, we expect our index + a fd == -1 */
+ /* first, we expect a protocol version */
+ if (ivshmem_client_read_one_msg(client, &tmp, &fd) < 0 ||
+ (tmp != IVSHMEM_PROTOCOL_VERSION) || fd != -1) {
+ IVSHMEM_CLIENT_DEBUG(client, "cannot read from server\n");
+ goto err_close;
+ }
+
+ /* then, we expect our index + a fd == -1 */
if (ivshmem_client_read_one_msg(client, &client->local.id, &fd) < 0 ||
client->local.id < 0 || fd != -1) {
- IVSHMEM_CLIENT_DEBUG(client, "cannot read from server\n");
+ IVSHMEM_CLIENT_DEBUG(client, "cannot read from server (2)\n");
goto err_close;
}
IVSHMEM_CLIENT_DEBUG(client, "our_id=%ld\n", client->local.id);
@@ -220,7 +227,7 @@ ivshmem_client_connect(IvshmemClient *client)
if (fd >= 0) {
close(fd);
}
- IVSHMEM_CLIENT_DEBUG(client, "cannot read from server (2)\n");
+ IVSHMEM_CLIENT_DEBUG(client, "cannot read from server (3)\n");
goto err_close;
}
client->shm_fd = fd;
@@ -23,6 +23,7 @@
#include <sys/select.h>
#include "qemu/queue.h"
+#include "hw/misc/ivshmem.h"
/**
* Maximum number of notification vectors supported by the client
@@ -100,6 +100,15 @@ ivshmem_server_send_initial_info(IvshmemServer *server, IvshmemServerPeer *peer)
{
int ret;
+ /* send our protocol version first */
+ ret = ivshmem_server_send_one_msg(peer->sock_fd, IVSHMEM_PROTOCOL_VERSION,
+ -1);
+ if (ret < 0) {
+ IVSHMEM_SERVER_DEBUG(server, "cannot send version: %s\n",
+ strerror(errno));
+ return -1;
+ }
+
/* send the peer id to the client */
ret = ivshmem_server_send_one_msg(peer->sock_fd, peer->id, -1);
if (ret < 0) {
@@ -32,6 +32,7 @@
#include <stdbool.h>
#include "qemu/queue.h"
+#include "hw/misc/ivshmem.h"
/**
* Maximum number of notification vectors supported by the server
@@ -64,6 +64,8 @@ It creates a shared memory object then waits for clients to connect on a unix
socket.
For each client (QEMU process) that connects to the server:
+- the server sends a protocol version, if client does not support it, the client
+ closes the communication,
- the server assigns an ID for this client and sends this ID to him as the first
message,
- the server sends a fd to the shared memory object to this client,
@@ -86,9 +88,10 @@ been provided in qemu.git/contrib/ivshmem-client for debug.
*QEMU as an ivshmem client*
-At initialisation, when creating the ivshmem device, QEMU gets its ID from the
-server then makes it available through BAR0 IVPosition register for the VM to
-use (see 'PCI device registers' subsection).
+At initialisation, when creating the ivshmem device, QEMU first receives a
+protocol version and closes communication with server if it does not match.
+Then, QEMU gets its ID from the server then makes it available through BAR0
+IVPosition register for the VM to use (see 'PCI device registers' subsection).
QEMU then uses the fd to the shared memory to map it to BAR2.
eventfds for all other clients received from the server are stored to implement
BAR0 Doorbell register (see 'PCI device registers' subsection).
@@ -27,6 +27,8 @@
#include "qemu/fifo8.h"
#include "sysemu/char.h"
+#include "hw/misc/ivshmem.h"
+
#include <sys/mman.h>
#include <sys/types.h>
#include <limits.h>
@@ -595,6 +597,31 @@ static void ivshmem_read(void *opaque, const uint8_t *buf, int size)
}
}
+static void ivshmem_check_version(void *opaque, const uint8_t * buf, int size)
+{
+ IVShmemState *s = opaque;
+ int tmp;
+ long version;
+
+ if (!fifo_update_and_get(s, buf, size,
+ &version, sizeof(version))) {
+ return;
+ }
+
+ tmp = qemu_chr_fe_get_msgfd(s->server_chr);
+ if (tmp != -1 || version != IVSHMEM_PROTOCOL_VERSION) {
+ fprintf(stderr, "incompatible version, you are connecting to a ivshmem-"
+ "server using a different protocol please check your setup\n");
+ qemu_chr_delete(s->server_chr);
+ s->server_chr = NULL;
+ return;
+ }
+
+ IVSHMEM_DPRINTF("version check ok, switch to real chardev handler\n");
+ qemu_chr_add_handlers(s->server_chr, ivshmem_can_receive, ivshmem_read,
+ ivshmem_event, s);
+}
+
/* Select the MSI-X vectors used by device.
* ivshmem maps events to vectors statically, so
* we just enable all vectors on init and after reset. */
@@ -768,8 +795,8 @@ static void pci_ivshmem_realize(PCIDevice *dev, Error **errp)
s->eventfd_chr = g_malloc0(s->vectors * sizeof(CharDriverState *));
- qemu_chr_add_handlers(s->server_chr, ivshmem_can_receive, ivshmem_read,
- ivshmem_event, s);
+ qemu_chr_add_handlers(s->server_chr, ivshmem_can_receive,
+ ivshmem_check_version, ivshmem_event, s);
} else {
/* just map the file immediately, we're not using a server */
int fd;