From: Paul Durrant
The blkif protocol has had provision for negotiation of multi-page shared
rings for some time now and many guest OS have support in their frontend
drivers.
This patch makes the necessary modifications to xen-disk support a shared
ring up to order 4 (i.e. 16 pages).
Signed-off-by: Paul Durrant
Signed-off-by: Stefano Stabellini
Reviewed-by: Stefano Stabellini
---
hw/block/xen_disk.c | 144 +---
1 file changed, 113 insertions(+), 31 deletions(-)
diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c
index 8218741..d42ed70 100644
--- a/hw/block/xen_disk.c
+++ b/hw/block/xen_disk.c
@@ -36,8 +36,6 @@
static int batch_maps = 0;
-static int max_requests = 32;
-
/* - */
#define BLOCK_SIZE 512
@@ -84,6 +82,8 @@ struct ioreq {
BlockAcctCookie acct;
};
+#define MAX_RING_PAGE_ORDER 4
+
struct XenBlkDev {
struct XenDevicexendev; /* must be first */
char*params;
@@ -94,7 +94,8 @@ struct XenBlkDev {
booldirectiosafe;
const char *fileproto;
const char *filename;
-int ring_ref;
+unsigned intring_ref[1 << MAX_RING_PAGE_ORDER];
+unsigned intnr_ring_ref;
void*sring;
int64_t file_blk;
int64_t file_size;
@@ -110,6 +111,7 @@ struct XenBlkDev {
int requests_total;
int requests_inflight;
int requests_finished;
+unsigned intmax_requests;
/* Persistent grants extension */
gbooleanfeature_discard;
@@ -199,7 +201,7 @@ static struct ioreq *ioreq_start(struct XenBlkDev *blkdev)
struct ioreq *ioreq = NULL;
if (QLIST_EMPTY(&blkdev->freelist)) {
-if (blkdev->requests_total >= max_requests) {
+if (blkdev->requests_total >= blkdev->max_requests) {
goto out;
}
/* allocate new struct */
@@ -904,7 +906,7 @@ static void blk_handle_requests(struct XenBlkDev *blkdev)
ioreq_runio_qemu_aio(ioreq);
}
-if (blkdev->more_work && blkdev->requests_inflight < max_requests) {
+if (blkdev->more_work && blkdev->requests_inflight < blkdev->max_requests)
{
qemu_bh_schedule(blkdev->bh);
}
}
@@ -917,15 +919,6 @@ static void blk_bh(void *opaque)
blk_handle_requests(blkdev);
}
-/*
- * We need to account for the grant allocations requiring contiguous
- * chunks; the worst case number would be
- * max_req * max_seg + (max_req - 1) * (max_seg - 1) + 1,
- * but in order to keep things simple just use
- * 2 * max_req * max_seg.
- */
-#define MAX_GRANTS(max_req, max_seg) (2 * (max_req) * (max_seg))
-
static void blk_alloc(struct XenDevice *xendev)
{
struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
@@ -937,11 +930,6 @@ static void blk_alloc(struct XenDevice *xendev)
if (xen_mode != XEN_EMULATE) {
batch_maps = 1;
}
-if (xengnttab_set_max_grants(xendev->gnttabdev,
-MAX_GRANTS(max_requests, BLKIF_MAX_SEGMENTS_PER_REQUEST)) < 0) {
-xen_pv_printf(xendev, 0, "xengnttab_set_max_grants failed: %s\n",
- strerror(errno));
-}
}
static void blk_parse_discard(struct XenBlkDev *blkdev)
@@ -1036,6 +1024,9 @@ static int blk_init(struct XenDevice *xendev)
!blkdev->feature_grant_copy);
xenstore_write_be_int(&blkdev->xendev, "info", info);
+xenstore_write_be_int(&blkdev->xendev, "max-ring-page-order",
+ MAX_RING_PAGE_ORDER);
+
blk_parse_discard(blkdev);
g_free(directiosafe);
@@ -1057,12 +1048,25 @@ out_error:
return -1;
}
+/*
+ * We need to account for the grant allocations requiring contiguous
+ * chunks; the worst case number would be
+ * max_req * max_seg + (max_req - 1) * (max_seg - 1) + 1,
+ * but in order to keep things simple just use
+ * 2 * max_req * max_seg.
+ */
+#define MAX_GRANTS(max_req, max_seg) (2 * (max_req) * (max_seg))
+
static int blk_connect(struct XenDevice *xendev)
{
struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
int pers, index, qflags;
bool readonly = true;
bool writethrough = true;
+int order, ring_ref;
+unsigned int ring_size, max_grants;
+unsigned int i;
+uint32_t *domids;
/* read-only ? */
if (blkdev->directiosafe) {
@@ -1137,9 +1141,42 @@ static int blk_connect(struct XenDevice *xendev)
xenstore_write_be_int64(&blkdev->xendev, "sectors",
blkdev->file_size / blkdev->file_blk);
-if (xenstore_read_fe_int(&blkdev->xendev, "ring-ref", &blkdev->ring_ref)
== -1) {
+if (xenstore_read_fe_int(&blkdev->xendev, "ring-page-order",
+ &order) == -1) {
+blkdev->nr_ring_ref = 1;
+
+
