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 <paul.durr...@citrix.com>
---
Cc: Stefano Stabellini <sstabell...@kernel.org>
Cc: Anthony Perard <anthony.per...@citrix.com>
Cc: Kevin Wolf <kw...@redhat.com>
Cc: Max Reitz <mre...@redhat.com>
v2:
- Fix memory leak in error path
- Print warning if ring-page-order exceeds limits
---
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 9b06e3aa81..0e6513708e 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 XenDevice xendev; /* must be first */
char *params;
@@ -94,7 +94,8 @@ struct XenBlkDev {
bool directiosafe;
const char *fileproto;
const char *filename;
- int ring_ref;
+ unsigned int ring_ref[1 << MAX_RING_PAGE_ORDER];
+ unsigned int nr_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 int max_requests;
/* Persistent grants extension */
gboolean feature_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 */
@@ -905,7 +907,7 @@ 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);
}
}
@@ -918,15 +920,6 @@ 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);
@@ -938,11 +931,6 @@ 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)
@@ -1037,6 +1025,9 @@ 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);
@@ -1058,12 +1049,25 @@ 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) {
@@ -1138,9 +1142,42 @@ 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;
+
+ if (xenstore_read_fe_int(&blkdev->xendev, "ring-ref",
+ &ring_ref) == -1) {
+ return -1;
+ }
+ blkdev->ring_ref[0] = ring_ref;
+
+ } else if (order >= 0 && order <= MAX_RING_PAGE_ORDER) {
+ blkdev->nr_ring_ref = 1 << order;
+
+ for (i = 0; i < blkdev->nr_ring_ref; i++) {
+ char *key;
+
+ key = g_strdup_printf("ring-ref%u", i);
+ if (!key) {
+ return -1;
+ }
+
+ if (xenstore_read_fe_int(&blkdev->xendev, key,
+ &ring_ref) == -1) {
+ g_free(key);
+ return -1;
+ }
+ blkdev->ring_ref[i] = ring_ref;
+
+ g_free(key);
+ }
+ } else {
+ xen_pv_printf(xendev, 0, "invalid ring-page-order: %d\n",
+ order);
return -1;
}
+
if (xenstore_read_fe_int(&blkdev->xendev, "event-channel",
&blkdev->xendev.remote_port) == -1) {
return -1;
@@ -1163,41 +1200,85 @@ static int blk_connect(struct XenDevice *xendev)
blkdev->protocol = BLKIF_PROTOCOL_NATIVE;
}
- blkdev->sring = xengnttab_map_grant_ref(blkdev->xendev.gnttabdev,
- blkdev->xendev.dom,
- blkdev->ring_ref,
- PROT_READ | PROT_WRITE);
+ ring_size = XC_PAGE_SIZE * blkdev->nr_ring_ref;
+ switch (blkdev->protocol) {
+ case BLKIF_PROTOCOL_NATIVE:
+ {
+ blkdev->max_requests = __CONST_RING_SIZE(blkif, ring_size);
+ break;
+ }
+ case BLKIF_PROTOCOL_X86_32:
+ {
+ blkdev->max_requests = __CONST_RING_SIZE(blkif_x86_32, ring_size);
+ break;
+ }
+ case BLKIF_PROTOCOL_X86_64:
+ {
+ blkdev->max_requests = __CONST_RING_SIZE(blkif_x86_64, ring_size);
+ break;
+ }
+ default:
+ return -1;
+ }
+
+ /* Calculate the maximum number of grants needed by ioreqs */
+ max_grants = MAX_GRANTS(blkdev->max_requests,
+ BLKIF_MAX_SEGMENTS_PER_REQUEST);
+ /* Add on the number needed for the ring pages */
+ max_grants += blkdev->nr_ring_ref;
+
+ if (xengnttab_set_max_grants(blkdev->xendev.gnttabdev, max_grants)) {
+ xen_pv_printf(xendev, 0, "xengnttab_set_max_grants failed: %s\n",
+ strerror(errno));
+ return -1;
+ }
+
+ domids = g_malloc0_n(blkdev->nr_ring_ref, sizeof(uint32_t));
+ for (i = 0; i < blkdev->nr_ring_ref; i++) {
+ domids[i] = blkdev->xendev.dom;
+ }
+
+ blkdev->sring = xengnttab_map_grant_refs(blkdev->xendev.gnttabdev,
+ blkdev->nr_ring_ref,
+ domids,
+ blkdev->ring_ref,
+ PROT_READ | PROT_WRITE);
+
+ g_free(domids);
+
if (!blkdev->sring) {
return -1;
}
+
blkdev->cnt_map++;
switch (blkdev->protocol) {
case BLKIF_PROTOCOL_NATIVE:
{
blkif_sring_t *sring_native = blkdev->sring;
- BACK_RING_INIT(&blkdev->rings.native, sring_native, XC_PAGE_SIZE);
+ BACK_RING_INIT(&blkdev->rings.native, sring_native, ring_size);
break;
}
case BLKIF_PROTOCOL_X86_32:
{
blkif_x86_32_sring_t *sring_x86_32 = blkdev->sring;
- BACK_RING_INIT(&blkdev->rings.x86_32_part, sring_x86_32, XC_PAGE_SIZE);
+ BACK_RING_INIT(&blkdev->rings.x86_32_part, sring_x86_32, ring_size);
break;
}
case BLKIF_PROTOCOL_X86_64:
{
blkif_x86_64_sring_t *sring_x86_64 = blkdev->sring;
- BACK_RING_INIT(&blkdev->rings.x86_64_part, sring_x86_64, XC_PAGE_SIZE);
+ BACK_RING_INIT(&blkdev->rings.x86_64_part, sring_x86_64, ring_size);
break;
}
}
if (blkdev->feature_persistent) {
/* Init persistent grants */
- blkdev->max_grants = max_requests * BLKIF_MAX_SEGMENTS_PER_REQUEST;
+ blkdev->max_grants = blkdev->max_requests *
+ BLKIF_MAX_SEGMENTS_PER_REQUEST;
blkdev->persistent_gnts = g_tree_new_full((GCompareDataFunc)int_cmp,
NULL, NULL,
batch_maps ?
@@ -1209,9 +1290,9 @@ static int blk_connect(struct XenDevice *xendev)
xen_be_bind_evtchn(&blkdev->xendev);
- xen_pv_printf(&blkdev->xendev, 1, "ok: proto %s, ring-ref %d, "
+ xen_pv_printf(&blkdev->xendev, 1, "ok: proto %s, nr-ring-ref %u, "
"remote port %d, local port %d\n",
- blkdev->xendev.protocol, blkdev->ring_ref,
+ blkdev->xendev.protocol, blkdev->nr_ring_ref,
blkdev->xendev.remote_port, blkdev->xendev.local_port);
return 0;
}
@@ -1228,7 +1309,8 @@ static void blk_disconnect(struct XenDevice *xendev)
xen_pv_unbind_evtchn(&blkdev->xendev);
if (blkdev->sring) {
- xengnttab_unmap(blkdev->xendev.gnttabdev, blkdev->sring, 1);
+ xengnttab_unmap(blkdev->xendev.gnttabdev, blkdev->sring,
+ blkdev->nr_ring_ref);
blkdev->cnt_map--;
blkdev->sring = NULL;
}
--
2.11.0
