[PATCH RFC v2 14/16] vfio-user: dma read/write operations

[Elena Ufimtseva <elena.ufimtseva@oracle.com>]

From: John Johnson <john.g.johnson@oracle.com>

Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
---
 hw/vfio/user-protocol.h | 11 +++++++
 hw/vfio/user.h          |  1 +
 hw/vfio/pci.c           | 63 ++++++++++++++++++++++++++++++++++++++++-
 hw/vfio/user.c          |  7 ++++-
 4 files changed, 80 insertions(+), 2 deletions(-)

diff --git a/hw/vfio/user-protocol.h b/hw/vfio/user-protocol.h
index ca53fce5f4..c5d9473f8f 100644
--- a/hw/vfio/user-protocol.h
+++ b/hw/vfio/user-protocol.h
@@ -171,6 +171,17 @@ typedef struct {
     char data[];
 } VFIOUserRegionRW;
 
+/*
+ * VFIO_USER_DMA_READ
+ * VFIO_USER_DMA_WRITE
+ */
+typedef struct {
+    VFIOUserHdr hdr;
+    uint64_t offset;
+    uint32_t count;
+    char data[];
+} VFIOUserDMARW;
+
 /*imported from struct vfio_bitmap */
 typedef struct {
     uint64_t pgsize;
diff --git a/hw/vfio/user.h b/hw/vfio/user.h
index 7786ab57c5..32e8b70d28 100644
--- a/hw/vfio/user.h
+++ b/hw/vfio/user.h
@@ -65,6 +65,7 @@ typedef struct VFIOProxy {
 
 VFIOProxy *vfio_user_connect_dev(SocketAddress *addr, Error **errp);
 void vfio_user_disconnect(VFIOProxy *proxy);
+uint64_t vfio_user_max_xfer(void);
 void vfio_user_set_reqhandler(VFIODevice *vbasdev,
                               int (*handler)(void *opaque, char *buf,
                                              VFIOUserFDs *fds),
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 2c9fcb2fa9..29a874c066 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -3406,11 +3406,72 @@ type_init(register_vfio_pci_dev_type)
  * vfio-user routines.
  */
 
-static int vfio_user_pci_process_req(void *opaque, char *buf, VFIOUserFDs *fds)
+static int vfio_user_dma_read(VFIOPCIDevice *vdev, VFIOUserDMARW *msg)
 {
+    PCIDevice *pdev = &vdev->pdev;
+    char *buf;
+    int size = msg->count + sizeof(VFIOUserDMARW);
+
+    if (msg->hdr.flags & VFIO_USER_NO_REPLY) {
+        return -EINVAL;
+    }
+    if (msg->count > vfio_user_max_xfer()) {
+        return -E2BIG;
+    }
+
+    buf = g_malloc0(size);
+    memcpy(buf, msg, sizeof(*msg));
+
+    pci_dma_read(pdev, msg->offset, buf + sizeof(*msg), msg->count);
+
+    vfio_user_send_reply(vdev->vbasedev.proxy, buf, size);
+    g_free(buf);
     return 0;
 }
 
+static int vfio_user_dma_write(VFIOPCIDevice *vdev,
+                               VFIOUserDMARW *msg)
+{
+    PCIDevice *pdev = &vdev->pdev;
+    char *buf = (char *)msg + sizeof(*msg);
+
+    /* make sure transfer count isn't larger than the message data */
+    if (msg->count > msg->hdr.size - sizeof(*msg)) {
+        return -E2BIG;
+    }
+
+    pci_dma_write(pdev, msg->offset, buf, msg->count);
+
+    if ((msg->hdr.flags & VFIO_USER_NO_REPLY) == 0) {
+        vfio_user_send_reply(vdev->vbasedev.proxy, (char *)msg,
+                             sizeof(msg->hdr));
+    }
+    return 0;
+}
+
+static int vfio_user_pci_process_req(void *opaque, char *buf, VFIOUserFDs *fds)
+{
+    VFIOPCIDevice *vdev = opaque;
+    VFIOUserHdr *hdr = (VFIOUserHdr *)buf;
+    int ret;
+
+    if (fds->recv_fds != 0) {
+        return -EINVAL;
+    }
+    switch (hdr->command) {
+    case VFIO_USER_DMA_READ:
+        ret = vfio_user_dma_read(vdev, (VFIOUserDMARW *)hdr);
+        break;
+    case VFIO_USER_DMA_WRITE:
+        ret = vfio_user_dma_write(vdev, (VFIOUserDMARW *)hdr);
+        break;
+    default:
+        error_printf("vfio_user_process_req unknown cmd %d\n", hdr->command);
+        ret = -ENOSYS;
+    }
+    return ret;
+}
+
 /*
  * Emulated devices don't use host hot reset
  */
diff --git a/hw/vfio/user.c b/hw/vfio/user.c
index 06bcd46e60..fcc041959c 100644
--- a/hw/vfio/user.c
+++ b/hw/vfio/user.c
@@ -54,6 +54,11 @@ static void vfio_user_send_recv(VFIOProxy *proxy, VFIOUserHdr *msg,
  * Functions called by main, CPU, or iothread threads
  */
 
+uint64_t vfio_user_max_xfer(void)
+{
+    return max_xfer_size;
+}
+
 static void vfio_user_shutdown(VFIOProxy *proxy)
 {
     qio_channel_shutdown(proxy->ioc, QIO_CHANNEL_SHUTDOWN_READ, NULL);
@@ -251,7 +256,7 @@ void vfio_user_recv(void *opaque)
         *reply->msg = msg;
         data = (char *)reply->msg + sizeof(msg);
     } else {
-        if (msg.size > max_xfer_size) {
+        if (msg.size > max_xfer_size + sizeof(VFIOUserDMARW)) {
             error_setg(&local_err, "vfio_user_recv request larger than max");
             goto fatal;
         }
-- 
2.25.1