[gve] Add support for raw DMA addressing

Raw DMA addressing allows the transmit and receive descriptors to
provide the DMA address of the data buffer directly, without requiring
the use of a pre-registered queue page list.  It is modelled in the
device as a magic "raw DMA" queue page list (with QPL ID 0xffffffff)
covering the whole of the DMA address space.

When using raw DMA addressing, the transmit and receive datapaths
could use the normal pattern of mapping I/O buffers directly, and
avoid copying packet data into and out of the fixed queue page list
ring buffer.  However, since we must retain support for queue page
list addressing (which requires this additional copying), we choose to
minimise code size by continuing to use the fixed ring buffer even
when using raw DMA addressing.

Add support for using raw DMA addressing by setting the queue page
list base device address appropriately, omitting the commands to
register and unregister the queue page lists, and specifying the raw
DMA QPL ID when creating the TX and RX queues.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/drivers/net/gve.c b/src/drivers/net/gve.c
index d1f129e2e40924926c15e28dc0a380e8d7b8abdb..80eb2e012e4e83c52de6ac2aabcf23dfcc37fc39 100644 (file)
--- a/src/drivers/net/gve.c
+++ b/src/drivers/net/gve.c
@@ -585,6 +585,10 @@ static int gve_register ( struct gve_nic *gve, struct gve_qpl *qpl ) {
        unsigned int i;
        int rc;
 
+       /* Do nothing if using raw DMA addressing */
+       if ( ! ( gve->mode & GVE_MODE_QPL ) )
+               return 0;
+
        /* Build page address list */
        for ( i = 0 ; i < qpl->count ; i++ ) {
                addr = ( qpl->data + ( i * GVE_PAGE_SIZE ) );
@@ -616,6 +620,10 @@ static int gve_register ( struct gve_nic *gve, struct gve_qpl *qpl ) {
 static int gve_unregister ( struct gve_nic *gve, struct gve_qpl *qpl ) {
        int rc;
 
+       /* Do nothing if using raw DMA addressing */
+       if ( ! ( gve->mode & GVE_MODE_QPL ) )
+               return 0;
+
        /* Issue command */
        if ( ( rc = gve_admin_simple ( gve, GVE_ADMIN_UNREGISTER,
                                       qpl->id ) ) != 0 ) {
@@ -629,9 +637,10 @@ static int gve_unregister ( struct gve_nic *gve, struct gve_qpl *qpl ) {
  * Construct command to create transmit queue
  *
  * @v queue            Transmit queue
+ * @v qpl              Queue page list ID
  * @v cmd              Admin queue command
  */
-static void gve_create_tx_param ( struct gve_queue *queue,
+static void gve_create_tx_param ( struct gve_queue *queue, uint32_t qpl,
                                  union gve_admin_command *cmd ) {
        struct gve_admin_create_tx *create = &cmd->create_tx;
        const struct gve_queue_type *type = queue->type;
@@ -640,7 +649,7 @@ static void gve_create_tx_param ( struct gve_queue *queue,
        create->res = cpu_to_be64 ( dma ( &queue->res_map, queue->res ) );
        create->desc =
                cpu_to_be64 ( dma ( &queue->desc_map, queue->desc.raw ) );
-       create->qpl_id = cpu_to_be32 ( type->qpl );
+       create->qpl_id = cpu_to_be32 ( qpl );
        create->notify_id = cpu_to_be32 ( type->irq );
        create->desc_count = cpu_to_be16 ( queue->count );
        if ( queue->cmplt.raw ) {
@@ -654,9 +663,10 @@ static void gve_create_tx_param ( struct gve_queue *queue,
  * Construct command to create receive queue
  *
  * @v queue            Receive queue
+ * @v qpl              Queue page list ID
  * @v cmd              Admin queue command
  */
-static void gve_create_rx_param ( struct gve_queue *queue,
+static void gve_create_rx_param ( struct gve_queue *queue, uint32_t qpl,
                                  union gve_admin_command *cmd ) {
        struct gve_admin_create_rx *create = &cmd->create_rx;
        const struct gve_queue_type *type = queue->type;
@@ -668,7 +678,7 @@ static void gve_create_rx_param ( struct gve_queue *queue,
                cpu_to_be64 ( dma ( &queue->desc_map, queue->desc.raw ) );
        create->cmplt =
                cpu_to_be64 ( dma ( &queue->cmplt_map, queue->cmplt.raw ) );
-       create->qpl_id = cpu_to_be32 ( type->qpl );
+       create->qpl_id = cpu_to_be32 ( qpl );
        create->desc_count = cpu_to_be16 ( queue->count );
        create->bufsz = cpu_to_be16 ( GVE_BUF_SIZE );
        create->cmplt_count = cpu_to_be16 ( queue->count );
@@ -686,6 +696,7 @@ static int gve_create_queue ( struct gve_nic *gve, struct gve_queue *queue ) {
        union gve_admin_command *cmd;
        unsigned int db_off;
        unsigned int evt_idx;
+       uint32_t qpl;
        int rc;
 
        /* Reset queue */
@@ -695,7 +706,8 @@ static int gve_create_queue ( struct gve_nic *gve, struct gve_queue *queue ) {
        /* Construct request */
        cmd = gve_admin_command ( gve );
        cmd->hdr.opcode = type->create;
-       type->param ( queue, cmd );
+       qpl = ( ( gve->mode & GVE_MODE_QPL ) ? type->qpl : GVE_RAW_QPL );
+       type->param ( queue, qpl, cmd );
 
        /* Issue command */
        if ( ( rc = gve_admin ( gve ) ) != 0 )
@@ -826,6 +838,8 @@ static int gve_alloc_qpl ( struct gve_nic *gve, struct gve_qpl *qpl,
        qpl->data = dma_umalloc ( gve->dma, &qpl->map, len, GVE_ALIGN );
        if ( ! qpl->data )
                return -ENOMEM;
+       qpl->base = ( ( gve->mode & GVE_MODE_QPL ) ?
+                     0 : dma ( &qpl->map, qpl->data ) );
 
        DBGC ( gve, "GVE %p QPL %#08x at [%08lx,%08lx)\n",
               gve, qpl->id, virt_to_phys ( qpl->data ),

diff --git a/src/drivers/net/gve.h b/src/drivers/net/gve.h
index e3d6c3f76b4ef2547d1e1cef856f7abd86371633..d3b7ca760c4490ff8600ea807f1b873eca5ea4a4 100644 (file)
--- a/src/drivers/net/gve.h
+++ b/src/drivers/net/gve.h
@@ -533,6 +533,9 @@ struct gve_qpl {
        physaddr_t base;
 };
 
+/** Raw DMA addressing queue page list ID */
+#define GVE_RAW_QPL 0xffffffff
+
 /**
  * Maximum number of transmit buffers
  *
@@ -676,9 +679,10 @@ struct gve_queue_type {
         * Populate command parameters to create queue
         *
         * @v queue             Descriptor queue
+        * @v qpl               Queue page list ID
         * @v cmd               Admin queue command
         */
-       void ( * param ) ( struct gve_queue *queue,
+       void ( * param ) ( struct gve_queue *queue, uint32_t qpl,
                           union gve_admin_command *cmd );
        /** Queue page list ID */
        uint32_t qpl;