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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 2/3] qemu-xen-dir/hw/block/xen_disk: Replace grant map by grant copy.
Grant copy operation is divided into two phases different for
'read' and 'write' operation.
For a 'read' operation the flow is as follow:
1. allocate local buffers for all the segments contained in
a request.
2. fill the request io vectors with the buffers' addresses
3. invoke read operation by qemu device
4. in the completition call grant copy
5. free the buffers
Function 'ioreq_read_init' implements 1. and 2. step. It is called
instead of 'ioreq_map' in 'ioreq_runio_qemu_aio'. Then the function
'ioreq_runio_qemu_aio' continues withouth changes performing step 3.
Steps 4. and 5. are called in the callback function
'qemu_aio_complete'. The ioreq_read' function is implemented for
step 4 which calls the new function 'xc_gnttab_copy_grant' presented
in the other part of the patch.
For a 'write' operation steps 4. happens before step 2.. First data
are copied from calling guest domains and then qemu operates on them.
For that step 'ioreq_write' function is added.
The function for grant map operation are removed.
---
hw/block/xen_disk.c | 419 +++++++++++++++++++++-------------------------------
1 file changed, 170 insertions(+), 249 deletions(-)
diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c
index 37e14d1..3e5eefd 100644
--- a/hw/block/xen_disk.c
+++ b/hw/block/xen_disk.c
@@ -79,13 +79,12 @@ struct ioreq {
int postsync;
uint8_t mapped;
- /* grant mapping */
- uint32_t domids[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+ /* grant copy */
+ uint16_t domids[BLKIF_MAX_SEGMENTS_PER_REQUEST];
uint32_t refs[BLKIF_MAX_SEGMENTS_PER_REQUEST];
int prot;
void *page[BLKIF_MAX_SEGMENTS_PER_REQUEST];
void *pages;
- int num_unmap;
/* aio status */
int aio_inflight;
@@ -123,13 +122,8 @@ struct XenBlkDev {
int requests_inflight;
int requests_finished;
- /* Persistent grants extension */
+ /* */
gboolean feature_discard;
- gboolean feature_persistent;
- GTree *persistent_gnts;
- GSList *persistent_regions;
- unsigned int persistent_gnt_count;
- unsigned int max_grants;
/* qemu block driver */
DriveInfo *dinfo;
@@ -164,46 +158,6 @@ static void ioreq_reset(struct ioreq *ioreq)
qemu_iovec_reset(&ioreq->v);
}
-static gint int_cmp(gconstpointer a, gconstpointer b, gpointer user_data)
-{
- uint ua = GPOINTER_TO_UINT(a);
- uint ub = GPOINTER_TO_UINT(b);
- return (ua > ub) - (ua < ub);
-}
-
-static void destroy_grant(gpointer pgnt)
-{
- PersistentGrant *grant = pgnt;
- XenGnttab gnt = grant->blkdev->xendev.gnttabdev;
-
- if (xc_gnttab_munmap(gnt, grant->page, 1) != 0) {
- xen_be_printf(&grant->blkdev->xendev, 0,
- "xc_gnttab_munmap failed: %s\n",
- strerror(errno));
- }
- grant->blkdev->persistent_gnt_count--;
- xen_be_printf(&grant->blkdev->xendev, 3,
- "unmapped grant %p\n", grant->page);
- g_free(grant);
-}
-
-static void remove_persistent_region(gpointer data, gpointer dev)
-{
- PersistentRegion *region = data;
- struct XenBlkDev *blkdev = dev;
- XenGnttab gnt = blkdev->xendev.gnttabdev;
-
- if (xc_gnttab_munmap(gnt, region->addr, region->num) != 0) {
- xen_be_printf(&blkdev->xendev, 0,
- "xc_gnttab_munmap region %p failed: %s\n",
- region->addr, strerror(errno));
- }
- xen_be_printf(&blkdev->xendev, 3,
- "unmapped grant region %p with %d pages\n",
- region->addr, region->num);
- g_free(region);
-}
-
static struct ioreq *ioreq_start(struct XenBlkDev *blkdev)
{
struct ioreq *ioreq = NULL;
@@ -314,7 +268,9 @@ static int ioreq_parse(struct ioreq *ioreq)
ioreq->refs[i] = ioreq->req.seg[i].gref;
mem = ioreq->req.seg[i].first_sect * blkdev->file_blk;
- len = (ioreq->req.seg[i].last_sect - ioreq->req.seg[i].first_sect + 1)
* blkdev->file_blk;
+ len = (ioreq->req.seg[i].last_sect - ioreq->req.seg[i].first_sect + 1)
+ * blkdev->file_blk;
+
qemu_iovec_add(&ioreq->v, (void*)mem, len);
}
if (ioreq->start + ioreq->v.size > blkdev->file_size) {
@@ -328,175 +284,151 @@ err:
return -1;
}
-static void ioreq_unmap(struct ioreq *ioreq)
+static void* get_buffer(void) {
+ void *buf;
+
+ buf = mmap(NULL, 1 << XC_PAGE_SHIFT, PROT_READ | PROT_WRITE,
+ MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+
+ if (unlikely(buf == MAP_FAILED))
+ return NULL;
+
+ return buf;
+}
+
+static int free_buffer(void* buf) {
+ return munmap(buf, 1 << XC_PAGE_SHIFT);
+}
+
+static int free_buffers(void** page, int count)
+{
+ int i, r = 0;
+
+ for (i = 0; i < count; i++) {
+
+ if(free_buffer(page[i]))
+ r = 1;
+
+ page[i] = NULL;
+ }
+
+ return r;
+}
+
+static int ioreq_write(struct ioreq *ioreq)
{
XenGnttab gnt = ioreq->blkdev->xendev.gnttabdev;
- int i;
+ uint16_t domids[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+ uint32_t refs[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+ uint32_t offset[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+ uint32_t len[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+ void *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+ int i, count = 0, rc, r;
+ /* Copy the data for write operation from guest grant pages addressed by
+ * domids, refs, offset, len to local buffers.
+ *
+ * Bufferes are then mapped to the pending request for further
+ * completition.
+ */
- if (ioreq->num_unmap == 0 || ioreq->mapped == 0) {
- return;
+ if (ioreq->v.niov == 0) {
+ r = 0; goto out;
}
- if (batch_maps) {
- if (!ioreq->pages) {
- return;
+
+ count = ioreq->v.niov;
+ for (i = 0; i < count; i++) {
+ domids[i] = ioreq->domids[i];
+ refs[i] = ioreq->refs[i];
+ offset[i] = ioreq->req.seg[i].first_sect * ioreq->blkdev->file_blk;
+ len[i] = (ioreq->req.seg[i].last_sect - ioreq->req.seg[i].first_sect +
1)
+ * ioreq->blkdev->file_blk;
+ pages[i] = get_buffer();
+
+ if(!pages[i]) {
+ xen_be_printf(&ioreq->blkdev->xendev, 0,
+ "failed to alloc page, errno %d \n", errno);
+ r = 1; goto out;
}
- if (xc_gnttab_munmap(gnt, ioreq->pages, ioreq->num_unmap) != 0) {
- xen_be_printf(&ioreq->blkdev->xendev, 0, "xc_gnttab_munmap failed:
%s\n",
- strerror(errno));
+ }
+ rc = xc_gnttab_copy_grant(gnt, count, domids, refs, pages, offset, len, 1);
+
+ if(rc) {
+ xen_be_printf(&ioreq->blkdev->xendev, 0,
+ "failed to copy data for write %d \n", rc);
+
+ if(free_buffers(ioreq->page, ioreq->v.niov)) {
+ xen_be_printf(&ioreq->blkdev->xendev, 0,
+ "failed to free page, errno %d \n", errno);
}
- ioreq->blkdev->cnt_map -= ioreq->num_unmap;
- ioreq->pages = NULL;
- } else {
- for (i = 0; i < ioreq->num_unmap; i++) {
- if (!ioreq->page[i]) {
- continue;
- }
- if (xc_gnttab_munmap(gnt, ioreq->page[i], 1) != 0) {
- xen_be_printf(&ioreq->blkdev->xendev, 0, "xc_gnttab_munmap
failed: %s\n",
- strerror(errno));
- }
- ioreq->blkdev->cnt_map--;
- ioreq->page[i] = NULL;
+ r = 1; goto out;
+ }
+
+ for (i = 0; i < ioreq->v.niov; i++) {
+ ioreq->page[i] = pages[i];
+ ioreq->v.iov[i].iov_base += (uintptr_t)pages[i];
+ }
+
+ r = 0;
+out:
+ return r;
+}
+
+static int ioreq_read_init(struct ioreq *ioreq)
+{
+ int i;
+
+ if (ioreq->v.niov == 0) {
+ return 0;
+ }
+
+ for (i = 0; i < ioreq->v.niov; i++) {
+ ioreq->page[i] = get_buffer();
+ if(!ioreq->page[i]) {
+ return -1;
}
+ ioreq->v.iov[i].iov_base += (uintptr_t)ioreq->page[i];
}
- ioreq->mapped = 0;
+
+ return 0;
}
-static int ioreq_map(struct ioreq *ioreq)
+
+static int ioreq_read(struct ioreq *ioreq)
{
XenGnttab gnt = ioreq->blkdev->xendev.gnttabdev;
- uint32_t domids[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+ uint16_t domids[BLKIF_MAX_SEGMENTS_PER_REQUEST];
uint32_t refs[BLKIF_MAX_SEGMENTS_PER_REQUEST];
- void *page[BLKIF_MAX_SEGMENTS_PER_REQUEST];
- int i, j, new_maps = 0;
- PersistentGrant *grant;
- PersistentRegion *region;
- /* domids and refs variables will contain the information necessary
- * to map the grants that are needed to fulfill this request.
- *
- * After mapping the needed grants, the page array will contain the
- * memory address of each granted page in the order specified in ioreq
- * (disregarding if it's a persistent grant or not).
+ uint32_t offset[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+ uint32_t len[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+ void *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+ int i, count = 0, rc;
+
+ /* Copy the data from local buffers to guest grant pages addressed by
+ * domids, refs, offset on the completition of read operation.
*/
- if (ioreq->v.niov == 0 || ioreq->mapped == 1) {
+ if (ioreq->v.niov == 0) {
return 0;
}
- if (ioreq->blkdev->feature_persistent) {
- for (i = 0; i < ioreq->v.niov; i++) {
- grant = g_tree_lookup(ioreq->blkdev->persistent_gnts,
- GUINT_TO_POINTER(ioreq->refs[i]));
-
- if (grant != NULL) {
- page[i] = grant->page;
- xen_be_printf(&ioreq->blkdev->xendev, 3,
- "using persistent-grant %" PRIu32 "\n",
- ioreq->refs[i]);
- } else {
- /* Add the grant to the list of grants that
- * should be mapped
- */
- domids[new_maps] = ioreq->domids[i];
- refs[new_maps] = ioreq->refs[i];
- page[i] = NULL;
- new_maps++;
- }
- }
- /* Set the protection to RW, since grants may be reused later
- * with a different protection than the one needed for this request
- */
- ioreq->prot = PROT_WRITE | PROT_READ;
- } else {
- /* All grants in the request should be mapped */
- memcpy(refs, ioreq->refs, sizeof(refs));
- memcpy(domids, ioreq->domids, sizeof(domids));
- memset(page, 0, sizeof(page));
- new_maps = ioreq->v.niov;
- }
- if (batch_maps && new_maps) {
- ioreq->pages = xc_gnttab_map_grant_refs
- (gnt, new_maps, domids, refs, ioreq->prot);
- if (ioreq->pages == NULL) {
- xen_be_printf(&ioreq->blkdev->xendev, 0,
- "can't map %d grant refs (%s, %d maps)\n",
- new_maps, strerror(errno), ioreq->blkdev->cnt_map);
- return -1;
- }
- for (i = 0, j = 0; i < ioreq->v.niov; i++) {
- if (page[i] == NULL) {
- page[i] = ioreq->pages + (j++) * XC_PAGE_SIZE;
- }
- }
- ioreq->blkdev->cnt_map += new_maps;
- } else if (new_maps) {
- for (i = 0; i < new_maps; i++) {
- ioreq->page[i] = xc_gnttab_map_grant_ref
- (gnt, domids[i], refs[i], ioreq->prot);
- if (ioreq->page[i] == NULL) {
- xen_be_printf(&ioreq->blkdev->xendev, 0,
- "can't map grant ref %d (%s, %d maps)\n",
- refs[i], strerror(errno),
ioreq->blkdev->cnt_map);
- ioreq->mapped = 1;
- ioreq_unmap(ioreq);
- return -1;
- }
- ioreq->blkdev->cnt_map++;
- }
- for (i = 0, j = 0; i < ioreq->v.niov; i++) {
- if (page[i] == NULL) {
- page[i] = ioreq->page[j++];
- }
- }
+ count = ioreq->v.niov;
+ for (i = 0; i < count; i++) {
+ domids[i] = ioreq->domids[i];
+ refs[i] = ioreq->refs[i];
+ offset[i] = ioreq->req.seg[i].first_sect * ioreq->blkdev->file_blk;
+ len[i] = (ioreq->req.seg[i].last_sect - ioreq->req.seg[i].first_sect +
1)
+ * ioreq->blkdev->file_blk;
+ pages[i] = ioreq->v.iov[i].iov_base;
}
- if (ioreq->blkdev->feature_persistent && new_maps != 0 &&
- (!batch_maps || (ioreq->blkdev->persistent_gnt_count + new_maps <=
- ioreq->blkdev->max_grants))) {
- /*
- * If we are using persistent grants and batch mappings only
- * add the new maps to the list of persistent grants if the whole
- * area can be persistently mapped.
- */
- if (batch_maps) {
- region = g_malloc0(sizeof(*region));
- region->addr = ioreq->pages;
- region->num = new_maps;
- ioreq->blkdev->persistent_regions = g_slist_append(
- ioreq->blkdev->persistent_regions,
- region);
- }
- while ((ioreq->blkdev->persistent_gnt_count <
ioreq->blkdev->max_grants)
- && new_maps) {
- /* Go through the list of newly mapped grants and add as many
- * as possible to the list of persistently mapped grants.
- *
- * Since we start at the end of ioreq->page(s), we only need
- * to decrease new_maps to prevent this granted pages from
- * being unmapped in ioreq_unmap.
- */
- grant = g_malloc0(sizeof(*grant));
- new_maps--;
- if (batch_maps) {
- grant->page = ioreq->pages + (new_maps) * XC_PAGE_SIZE;
- } else {
- grant->page = ioreq->page[new_maps];
- }
- grant->blkdev = ioreq->blkdev;
- xen_be_printf(&ioreq->blkdev->xendev, 3,
- "adding grant %" PRIu32 " page: %p\n",
- refs[new_maps], grant->page);
- g_tree_insert(ioreq->blkdev->persistent_gnts,
- GUINT_TO_POINTER(refs[new_maps]),
- grant);
- ioreq->blkdev->persistent_gnt_count++;
- }
- assert(!batch_maps || new_maps == 0);
- }
- for (i = 0; i < ioreq->v.niov; i++) {
- ioreq->v.iov[i].iov_base += (uintptr_t)page[i];
+
+ rc = xc_gnttab_copy_grant(gnt, count, domids, refs, pages, offset, len, 0);
+
+ if(rc) {
+ xen_be_printf(&ioreq->blkdev->xendev, 0,
+ "failed to copy data to guest %d \n", rc);
+ return -1;
}
- ioreq->mapped = 1;
- ioreq->num_unmap = new_maps;
+
return 0;
}
@@ -529,7 +461,23 @@ static void qemu_aio_complete(void *opaque, int ret)
}
ioreq->status = ioreq->aio_errors ? BLKIF_RSP_ERROR : BLKIF_RSP_OKAY;
- ioreq_unmap(ioreq);
+
+ switch(ioreq->req.operation) {
+ case BLKIF_OP_READ:
+ if(ioreq_read(ioreq)) {
+ xen_be_printf(&ioreq->blkdev->xendev, 0,
+ "failed to copy read data to guest\n");
+ }
+ case BLKIF_OP_WRITE:
+ if(free_buffers(ioreq->page, ioreq->v.niov)) {
+ xen_be_printf(&ioreq->blkdev->xendev, 0,
+ "failed to free page, errno %d \n", errno);
+ }
+ break;
+ default:
+ break;
+ }
+
ioreq_finish(ioreq);
switch (ioreq->req.operation) {
case BLKIF_OP_WRITE:
@@ -551,8 +499,25 @@ static int ioreq_runio_qemu_aio(struct ioreq *ioreq)
{
struct XenBlkDev *blkdev = ioreq->blkdev;
- if (ioreq->req.nr_segments && ioreq_map(ioreq) == -1) {
- goto err_no_map;
+ switch (ioreq->req.operation) {
+ case BLKIF_OP_READ:
+ if (ioreq_read_init(ioreq)) {
+ xen_be_printf(&ioreq->blkdev->xendev, 0,
+ "failed to initialize buffers for"
+ "copy data to guest %d \n", errno);
+ goto out;
+ }
+ break;
+ case BLKIF_OP_WRITE:
+ case BLKIF_OP_FLUSH_DISKCACHE:
+ if (ioreq_write(ioreq)) {
+ xen_be_printf(&ioreq->blkdev->xendev, 0,
+ "failed to write data from guest\n");
+ goto out;
+ }
+ break;
+ default:
+ break;
}
ioreq->aio_inflight++;
@@ -594,16 +559,14 @@ static int ioreq_runio_qemu_aio(struct ioreq *ioreq)
}
default:
/* unknown operation (shouldn't happen -- parse catches this) */
- goto err;
+ goto out;
}
qemu_aio_complete(ioreq, 0);
return 0;
-err:
- ioreq_unmap(ioreq);
-err_no_map:
+out:
ioreq_finish(ioreq);
ioreq->status = BLKIF_RSP_ERROR;
return -1;
@@ -764,11 +727,6 @@ static void blk_alloc(struct XenDevice *xendev)
if (xen_mode != XEN_EMULATE) {
batch_maps = 1;
}
- if (xc_gnttab_set_max_grants(xendev->gnttabdev,
- MAX_GRANTS(max_requests, BLKIF_MAX_SEGMENTS_PER_REQUEST)) < 0) {
- xen_be_printf(xendev, 0, "xc_gnttab_set_max_grants failed: %s\n",
- strerror(errno));
- }
}
static void blk_parse_discard(struct XenBlkDev *blkdev)
@@ -880,7 +838,7 @@ out_error:
static int blk_connect(struct XenDevice *xendev)
{
struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
- int pers, index, qflags;
+ int index, qflags;
bool readonly = true;
/* read-only ? */
@@ -958,11 +916,6 @@ static int blk_connect(struct XenDevice *xendev)
&blkdev->xendev.remote_port) == -1) {
return -1;
}
- if (xenstore_read_fe_int(&blkdev->xendev, "feature-persistent", &pers)) {
- blkdev->feature_persistent = FALSE;
- } else {
- blkdev->feature_persistent = !!pers;
- }
blkdev->protocol = BLKIF_PROTOCOL_NATIVE;
if (blkdev->xendev.protocol) {
@@ -1006,18 +959,6 @@ static int blk_connect(struct XenDevice *xendev)
}
}
- if (blkdev->feature_persistent) {
- /* Init persistent grants */
- blkdev->max_grants = max_requests * BLKIF_MAX_SEGMENTS_PER_REQUEST;
- blkdev->persistent_gnts = g_tree_new_full((GCompareDataFunc)int_cmp,
- NULL, NULL,
- batch_maps ?
- (GDestroyNotify)g_free :
- (GDestroyNotify)destroy_grant);
- blkdev->persistent_regions = NULL;
- blkdev->persistent_gnt_count = 0;
- }
-
xen_be_bind_evtchn(&blkdev->xendev);
xen_be_printf(&blkdev->xendev, 1, "ok: proto %s, ring-ref %d, "
@@ -1043,26 +984,6 @@ static void blk_disconnect(struct XenDevice *xendev)
blkdev->cnt_map--;
blkdev->sring = NULL;
}
-
- /*
- * Unmap persistent grants before switching to the closed state
- * so the frontend can free them.
- *
- * In the !batch_maps case g_tree_destroy will take care of unmapping
- * the grant, but in the batch_maps case we need to iterate over every
- * region in persistent_regions and unmap it.
- */
- if (blkdev->feature_persistent) {
- g_tree_destroy(blkdev->persistent_gnts);
- assert(batch_maps || blkdev->persistent_gnt_count == 0);
- if (batch_maps) {
- blkdev->persistent_gnt_count = 0;
- g_slist_foreach(blkdev->persistent_regions,
- (GFunc)remove_persistent_region, blkdev);
- g_slist_free(blkdev->persistent_regions);
- }
- blkdev->feature_persistent = false;
- }
}
static int blk_free(struct XenDevice *xendev)
--
1.9.1
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