Merge remote-tracking branch 'sstabellini/tags/xen-20161128-tag' into staging

Xen 2016/11/28

# gpg: Signature made Mon 28 Nov 2016 07:37:33 PM GMT
# gpg:                using RSA key 0x894F8F4870E1AE90
# gpg: Good signature from "Stefano Stabellini <sstabellini@kernel.org>"
# gpg:                 aka "Stefano Stabellini <stefano.stabellini@eu.citrix.com>"
# Primary key fingerprint: D04E 33AB A51F 67BA 07D3  0AEA 894F 8F48 70E1 AE90

* sstabellini/tags/xen-20161128-tag:
  xen: ignore direction in bufioreq handling
  xen: slightly simplify bufioreq handling
  xen: fix quad word bufioreq handling
  xen_disk: split discard input to match internal representation

Message-id: alpine.DEB.2.10.1611281137590.21858@sstabellini-ThinkPad-X260
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

2 files changed, 52 insertions, 12 deletions

diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c
index 3a7dc194e2..456a2d5694 100644
--- a/hw/block/xen_disk.c
+++ b/hw/block/xen_disk.c
@@ -660,6 +660,38 @@ static void qemu_aio_complete(void *opaque, int ret)
     qemu_bh_schedule(ioreq->blkdev->bh);
 }
 
+static bool blk_split_discard(struct ioreq *ioreq, blkif_sector_t sector_number,
+                              uint64_t nr_sectors)
+{
+    struct XenBlkDev *blkdev = ioreq->blkdev;
+    int64_t byte_offset;
+    int byte_chunk;
+    uint64_t byte_remaining, limit;
+    uint64_t sec_start = sector_number;
+    uint64_t sec_count = nr_sectors;
+
+    /* Wrap around, or overflowing byte limit? */
+    if (sec_start + sec_count < sec_count ||
+        sec_start + sec_count > INT64_MAX >> BDRV_SECTOR_BITS) {
+        return false;
+    }
+
+    limit = BDRV_REQUEST_MAX_SECTORS << BDRV_SECTOR_BITS;
+    byte_offset = sec_start << BDRV_SECTOR_BITS;
+    byte_remaining = sec_count << BDRV_SECTOR_BITS;
+
+    do {
+        byte_chunk = byte_remaining > limit ? limit : byte_remaining;
+        ioreq->aio_inflight++;
+        blk_aio_pdiscard(blkdev->blk, byte_offset, byte_chunk,
+                         qemu_aio_complete, ioreq);
+        byte_remaining -= byte_chunk;
+        byte_offset += byte_chunk;
+    } while (byte_remaining > 0);
+
+    return true;
+}
+
 static int ioreq_runio_qemu_aio(struct ioreq *ioreq)
 {
     struct XenBlkDev *blkdev = ioreq->blkdev;
@@ -708,12 +740,10 @@ static int ioreq_runio_qemu_aio(struct ioreq *ioreq)
         break;
     case BLKIF_OP_DISCARD:
     {
-        struct blkif_request_discard *discard_req = (void *)&ioreq->req;
-        ioreq->aio_inflight++;
-        blk_aio_pdiscard(blkdev->blk,
-                         discard_req->sector_number << BDRV_SECTOR_BITS,
-                         discard_req->nr_sectors << BDRV_SECTOR_BITS,
-                         qemu_aio_complete, ioreq);
+        struct blkif_request_discard *req = (void *)&ioreq->req;
+        if (!blk_split_discard(ioreq, req->sector_number, req->nr_sectors)) {
+            goto err;
+        }
         break;
     }
     default:
diff --git a/xen-hvm.c b/xen-hvm.c
index 99b8ee8a4f..0892361cc2 100644
--- a/xen-hvm.c
+++ b/xen-hvm.c
@@ -995,6 +995,9 @@ static int handle_buffered_iopage(XenIOState *state)
     }
 
     memset(&req, 0x00, sizeof(req));
+    req.state = STATE_IOREQ_READY;
+    req.count = 1;
+    req.dir = IOREQ_WRITE;
 
     for (;;) {
         uint32_t rdptr = buf_page->read_pointer, wrptr;
@@ -1009,18 +1012,16 @@ static int handle_buffered_iopage(XenIOState *state)
             break;
         }
         buf_req = &buf_page->buf_ioreq[rdptr % IOREQ_BUFFER_SLOT_NUM];
-        req.size = 1UL << buf_req->size;
-        req.count = 1;
+        req.size = 1U << buf_req->size;
         req.addr = buf_req->addr;
         req.data = buf_req->data;
-        req.state = STATE_IOREQ_READY;
-        req.dir = buf_req->dir;
-        req.df = 1;
         req.type = buf_req->type;
-        req.data_is_ptr = 0;
         xen_rmb();
         qw = (req.size == 8);
         if (qw) {
+            if (rdptr + 1 == wrptr) {
+                hw_error("Incomplete quad word buffered ioreq");
+            }
             buf_req = &buf_page->buf_ioreq[(rdptr + 1) %
                                            IOREQ_BUFFER_SLOT_NUM];
             req.data |= ((uint64_t)buf_req->data) << 32;
@@ -1029,6 +1030,15 @@ static int handle_buffered_iopage(XenIOState *state)
 
         handle_ioreq(state, &req);
 
+        /* Only req.data may get updated by handle_ioreq(), albeit even that
+         * should not happen as such data would never make it to the guest (we
+         * can only usefully see writes here after all).
+         */
+        assert(req.state == STATE_IOREQ_READY);
+        assert(req.count == 1);
+        assert(req.dir == IOREQ_WRITE);
+        assert(!req.data_is_ptr);
+
         atomic_add(&buf_page->read_pointer, qw + 1);
     }