xen: add block device backend driver. (Gerd Hoffmann)

This patch adds a block device backend driver to qemu.  It is a pure
userspace implemention using the gntdev interface.  It uses "qdisk" as
backend name in xenstore so it doesn't interfere with the other existing
backends (blkback aka "vbd" and tapdisk aka "tap").
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@7223 c046a42c-6fe2-441c-8c8c-71466251a162

Makefile.target

@@ -562,7 +562,7 @@ endif
 
 # xen backend driver support
 XEN_OBJS := xen_machine_pv.o xen_backend.o
-XEN_OBJS += xen_console.o xenfb.o
+XEN_OBJS += xen_console.o xenfb.o xen_disk.o
 ifeq ($(CONFIG_XEN), yes)
   OBJS += $(XEN_OBJS)
   LIBS += $(XEN_LIBS)

hw/xen_backend.h

@@ -2,6 +2,7 @@
 #define QEMU_HW_XEN_BACKEND_H 1
 
 #include "xen_common.h"
+#include "sysemu.h"
 
 /* ------------------------------------------------------------- */
 
@@ -87,6 +88,7 @@ void xen_be_printf(struct XenDevice *xendev, int msg_level, const char *fmt, ...
 extern struct XenDevOps xen_console_ops;      /* xen_console.c     */
 extern struct XenDevOps xen_kbdmouse_ops;     /* xen_framebuffer.c */
 extern struct XenDevOps xen_framebuffer_ops;  /* xen_framebuffer.c */
+extern struct XenDevOps xen_blkdev_ops;       /* xen_disk.c        */
 
 void xen_init_display(int domid);
 

hw/xen_blkif.h

+#ifndef __XEN_BLKIF_H__
+#define __XEN_BLKIF_H__
+
+#include <xen/io/ring.h>
+#include <xen/io/blkif.h>
+#include <xen/io/protocols.h>
+
+/* Not a real protocol.  Used to generate ring structs which contain
+ * the elements common to all protocols only.  This way we get a
+ * compiler-checkable way to use common struct elements, so we can
+ * avoid using switch(protocol) in a number of places.  */
+struct blkif_common_request {
+	char dummy;
+};
+struct blkif_common_response {
+	char dummy;
+};
+
+/* i386 protocol version */
+#pragma pack(push, 4)
+struct blkif_x86_32_request {
+	uint8_t        operation;    /* BLKIF_OP_???                         */
+	uint8_t        nr_segments;  /* number of segments                   */
+	blkif_vdev_t   handle;       /* only for read/write requests         */
+	uint64_t       id;           /* private guest value, echoed in resp  */
+	blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
+	struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+};
+struct blkif_x86_32_response {
+	uint64_t        id;              /* copied from request */
+	uint8_t         operation;       /* copied from request */
+	int16_t         status;          /* BLKIF_RSP_???       */
+};
+typedef struct blkif_x86_32_request blkif_x86_32_request_t;
+typedef struct blkif_x86_32_response blkif_x86_32_response_t;
+#pragma pack(pop)
+
+/* x86_64 protocol version */
+struct blkif_x86_64_request {
+	uint8_t        operation;    /* BLKIF_OP_???                         */
+	uint8_t        nr_segments;  /* number of segments                   */
+	blkif_vdev_t   handle;       /* only for read/write requests         */
+	uint64_t       __attribute__((__aligned__(8))) id;
+	blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
+	struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+};
+struct blkif_x86_64_response {
+	uint64_t       __attribute__((__aligned__(8))) id;
+	uint8_t         operation;       /* copied from request */
+	int16_t         status;          /* BLKIF_RSP_???       */
+};
+typedef struct blkif_x86_64_request blkif_x86_64_request_t;
+typedef struct blkif_x86_64_response blkif_x86_64_response_t;
+
+DEFINE_RING_TYPES(blkif_common, struct blkif_common_request, struct blkif_common_response);
+DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request, struct blkif_x86_32_response);
+DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request, struct blkif_x86_64_response);
+
+union blkif_back_rings {
+	blkif_back_ring_t        native;
+	blkif_common_back_ring_t common;
+	blkif_x86_32_back_ring_t x86_32;
+	blkif_x86_64_back_ring_t x86_64;
+};
+typedef union blkif_back_rings blkif_back_rings_t;
+
+enum blkif_protocol {
+	BLKIF_PROTOCOL_NATIVE = 1,
+	BLKIF_PROTOCOL_X86_32 = 2,
+	BLKIF_PROTOCOL_X86_64 = 3,
+};
+
+static void inline blkif_get_x86_32_req(blkif_request_t *dst, blkif_x86_32_request_t *src)
+{
+	int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
+
+	dst->operation = src->operation;
+	dst->nr_segments = src->nr_segments;
+	dst->handle = src->handle;
+	dst->id = src->id;
+	dst->sector_number = src->sector_number;
+	if (n > src->nr_segments)
+		n = src->nr_segments;
+	for (i = 0; i < n; i++)
+		dst->seg[i] = src->seg[i];
+}
+
+static void inline blkif_get_x86_64_req(blkif_request_t *dst, blkif_x86_64_request_t *src)
+{
+	int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
+
+	dst->operation = src->operation;
+	dst->nr_segments = src->nr_segments;
+	dst->handle = src->handle;
+	dst->id = src->id;
+	dst->sector_number = src->sector_number;
+	if (n > src->nr_segments)
+		n = src->nr_segments;
+	for (i = 0; i < n; i++)
+		dst->seg[i] = src->seg[i];
+}
+
+#endif /* __XEN_BLKIF_H__ */

hw/xen_machine_pv.c

@@ -59,6 +59,7 @@ static void xen_init_pv(ram_addr_t ram_size, int vga_ram_size,
     xen_be_register("console", &xen_console_ops);
     xen_be_register("vkbd", &xen_kbdmouse_ops);
     xen_be_register("vfb", &xen_framebuffer_ops);
+    xen_be_register("qdisk", &xen_blkdev_ops);
 
     /* setup framebuffer */
     xen_init_display(xen_domid);

sysemu.h

@@ -131,7 +131,7 @@ extern unsigned int nb_prom_envs;
 #endif
 
 typedef enum {
-    IF_IDE, IF_SCSI, IF_FLOPPY, IF_PFLASH, IF_MTD, IF_SD, IF_VIRTIO
+    IF_IDE, IF_SCSI, IF_FLOPPY, IF_PFLASH, IF_MTD, IF_SD, IF_VIRTIO, IF_XEN
 } BlockInterfaceType;
 
 typedef enum {

vl.c

@@ -2373,7 +2373,10 @@ int drive_init(struct drive_opt *arg, int snapshot, void *opaque)
         } else if (!strcmp(buf, "virtio")) {
             type = IF_VIRTIO;
             max_devs = 0;
-        } else {
+	} else if (!strcmp(buf, "xen")) {
+	    type = IF_XEN;
+            max_devs = 0;
+	} else {
             fprintf(stderr, "qemu: '%s' unsupported bus type '%s'\n", str, buf);
             return -1;
 	}
@@ -2587,6 +2590,7 @@ int drive_init(struct drive_opt *arg, int snapshot, void *opaque)
     switch(type) {
     case IF_IDE:
     case IF_SCSI:
+    case IF_XEN:
         switch(media) {
 	case MEDIA_DISK:
             if (cyls != 0) {