vfio-user: implement VFIO_USER_DEVICE_GET_INFO

Add support for getting basic device information.

Originally-by: John Johnson <john.g.johnson@oracle.com>
Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
Signed-off-by: John Levon <john.levon@nutanix.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/qemu-devel/20250625193012.2316242-6-john.levon@nutanix.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

8 files changed, 107 insertions, 7 deletions

diff --git a/hw/vfio-user/container.c b/hw/vfio-user/container.c
index 2367332..f5bfd54 100644
--- a/hw/vfio-user/container.c
+++ b/hw/vfio-user/container.c
@@ -11,6 +11,7 @@
 #include "qemu/osdep.h"
 
 #include "hw/vfio-user/container.h"
+#include "hw/vfio-user/device.h"
 #include "hw/vfio/vfio-cpr.h"
 #include "hw/vfio/vfio-device.h"
 #include "hw/vfio/vfio-listener.h"
@@ -140,7 +141,12 @@ static void vfio_user_container_disconnect(VFIOUserContainer *container)
 static bool vfio_user_device_get(VFIOUserContainer *container,
                                  VFIODevice *vbasedev, Error **errp)
 {
-    struct vfio_device_info info = { 0 };
+    struct vfio_device_info info = { .argsz = sizeof(info) };
+
+
+    if (!vfio_user_get_device_info(vbasedev->proxy, &info, errp)) {
+        return false;
+    }
 
     vbasedev->fd = -1;
 
diff --git a/hw/vfio-user/device.c b/hw/vfio-user/device.c
new file mode 100644
index 0000000..4212fef
--- /dev/null
+++ b/hw/vfio-user/device.c
@@ -0,0 +1,55 @@
+/*
+ * vfio protocol over a UNIX socket device handling.
+ *
+ * Copyright © 2018, 2021 Oracle and/or its affiliates.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qemu/error-report.h"
+
+#include "hw/vfio-user/device.h"
+#include "hw/vfio-user/trace.h"
+
+/*
+ * These are to defend against a malign server trying
+ * to force us to run out of memory.
+ */
+#define VFIO_USER_MAX_REGIONS   100
+#define VFIO_USER_MAX_IRQS      50
+
+bool vfio_user_get_device_info(VFIOUserProxy *proxy,
+                               struct vfio_device_info *info, Error **errp)
+{
+    VFIOUserDeviceInfo msg;
+    uint32_t argsz = sizeof(msg) - sizeof(msg.hdr);
+
+    memset(&msg, 0, sizeof(msg));
+    vfio_user_request_msg(&msg.hdr, VFIO_USER_DEVICE_GET_INFO, sizeof(msg), 0);
+    msg.argsz = argsz;
+
+    if (!vfio_user_send_wait(proxy, &msg.hdr, NULL, 0, errp)) {
+        return false;
+    }
+
+    if (msg.hdr.flags & VFIO_USER_ERROR) {
+        error_setg_errno(errp, -msg.hdr.error_reply,
+                         "VFIO_USER_DEVICE_GET_INFO failed");
+        return false;
+    }
+
+    trace_vfio_user_get_info(msg.num_regions, msg.num_irqs);
+
+    memcpy(info, &msg.argsz, argsz);
+
+    /* defend against a malicious server */
+    if (info->num_regions > VFIO_USER_MAX_REGIONS ||
+        info->num_irqs > VFIO_USER_MAX_IRQS) {
+        error_setg_errno(errp, EINVAL, "invalid reply");
+        return false;
+    }
+
+    return true;
+}
diff --git a/hw/vfio-user/device.h b/hw/vfio-user/device.h
new file mode 100644
index 0000000..ef3f71e
--- /dev/null
+++ b/hw/vfio-user/device.h
@@ -0,0 +1,20 @@
+#ifndef VFIO_USER_DEVICE_H
+#define VFIO_USER_DEVICE_H
+
+/*
+ * vfio protocol over a UNIX socket device handling.
+ *
+ * Copyright © 2018, 2021 Oracle and/or its affiliates.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "linux/vfio.h"
+
+#include "hw/vfio-user/proxy.h"
+
+bool vfio_user_get_device_info(VFIOUserProxy *proxy,
+                               struct vfio_device_info *info, Error **errp);
+
+#endif /* VFIO_USER_DEVICE_H */
diff --git a/hw/vfio-user/meson.build b/hw/vfio-user/meson.build
index 9e85a8e..2ed0ae5 100644
--- a/hw/vfio-user/meson.build
+++ b/hw/vfio-user/meson.build
@@ -3,6 +3,7 @@
 vfio_user_ss = ss.source_set()
 vfio_user_ss.add(files(
   'container.c',
+  'device.c',
   'pci.c',
   'proxy.c',
 ))
diff --git a/hw/vfio-user/protocol.h b/hw/vfio-user/protocol.h
index 2d52d0f..e0bba68 100644
--- a/hw/vfio-user/protocol.h
+++ b/hw/vfio-user/protocol.h
@@ -112,4 +112,16 @@ typedef struct {
  */
 #define VFIO_USER_DEF_MAX_BITMAP (256 * 1024 * 1024)
 
+/*
+ * VFIO_USER_DEVICE_GET_INFO
+ * imported from struct vfio_device_info
+ */
+typedef struct {
+    VFIOUserHdr hdr;
+    uint32_t argsz;
+    uint32_t flags;
+    uint32_t num_regions;
+    uint32_t num_irqs;
+} VFIOUserDeviceInfo;
+
 #endif /* VFIO_USER_PROTOCOL_H */
diff --git a/hw/vfio-user/proxy.c b/hw/vfio-user/proxy.c
index 874142e..aed7b22 100644
--- a/hw/vfio-user/proxy.c
+++ b/hw/vfio-user/proxy.c
@@ -35,8 +35,6 @@ static void vfio_user_send(void *opaque);
 static void vfio_user_cb(void *opaque);
 
 static void vfio_user_request(void *opaque);
-static void vfio_user_request_msg(VFIOUserHdr *hdr, uint16_t cmd,
-                                  uint32_t size, uint32_t flags);
 
 static inline void vfio_user_set_error(VFIOUserHdr *hdr, uint32_t err)
 {
@@ -626,8 +624,8 @@ static bool vfio_user_send_queued(VFIOUserProxy *proxy, VFIOUserMsg *msg,
  *
  * In either case, the caller must free @hdr and @fds if needed.
  */
-static bool vfio_user_send_wait(VFIOUserProxy *proxy, VFIOUserHdr *hdr,
-                                VFIOUserFDs *fds, int rsize, Error **errp)
+bool vfio_user_send_wait(VFIOUserProxy *proxy, VFIOUserHdr *hdr,
+                         VFIOUserFDs *fds, int rsize, Error **errp)
 {
     VFIOUserMsg *msg;
     bool ok = false;
@@ -802,8 +800,8 @@ void vfio_user_disconnect(VFIOUserProxy *proxy)
     g_free(proxy);
 }
 
-static void vfio_user_request_msg(VFIOUserHdr *hdr, uint16_t cmd,
-                                  uint32_t size, uint32_t flags)
+void vfio_user_request_msg(VFIOUserHdr *hdr, uint16_t cmd,
+                           uint32_t size, uint32_t flags)
 {
     static uint16_t next_id;
 
diff --git a/hw/vfio-user/proxy.h b/hw/vfio-user/proxy.h
index 5bc890a..837b02a 100644
--- a/hw/vfio-user/proxy.h
+++ b/hw/vfio-user/proxy.h
@@ -12,7 +12,9 @@
 #include "io/channel.h"
 #include "io/channel-socket.h"
 
+#include "qemu/queue.h"
 #include "qemu/sockets.h"
+#include "qemu/thread.h"
 #include "hw/vfio-user/protocol.h"
 
 typedef struct {
@@ -96,4 +98,9 @@ void vfio_user_set_handler(VFIODevice *vbasedev,
                            void *reqarg);
 bool vfio_user_validate_version(VFIOUserProxy *proxy, Error **errp);
 
+void vfio_user_request_msg(VFIOUserHdr *hdr, uint16_t cmd,
+                           uint32_t size, uint32_t flags);
+bool vfio_user_send_wait(VFIOUserProxy *proxy, VFIOUserHdr *hdr,
+                         VFIOUserFDs *fds, int rsize, Error **errp);
+
 #endif /* VFIO_USER_PROXY_H */
diff --git a/hw/vfio-user/trace-events b/hw/vfio-user/trace-events
index a965c7b..b7312d6 100644
--- a/hw/vfio-user/trace-events
+++ b/hw/vfio-user/trace-events
@@ -8,3 +8,4 @@ vfio_user_recv_read(uint16_t id, int read) " id 0x%x read 0x%x"
 vfio_user_recv_request(uint16_t cmd) " command 0x%x"
 vfio_user_send_write(uint16_t id, int wrote) " id 0x%x wrote 0x%x"
 vfio_user_version(uint16_t major, uint16_t minor, const char *caps) " major %d minor %d caps: %s"
+vfio_user_get_info(uint32_t nregions, uint32_t nirqs) " #regions %d #irqs %d"