Merge remote-tracking branch 'remotes/jnsnow/tags/ide-pull-request' into staging

# gpg: Signature made Sat Jul  4 07:06:08 2015 BST using RSA key ID AAFC390E
# gpg: Good signature from "John Snow (John Huston) <jsnow@redhat.com>"
# gpg: WARNING: This key is not certified with sufficiently trusted signatures!
# gpg:          It is not certain that the signature belongs to the owner.
# Primary key fingerprint: FAEB 9711 A12C F475 812F  18F2 88A9 064D 1835 61EB
#      Subkey fingerprint: F9B7 ABDB BCAC DF95 BE76  CBD0 7DEF 8106 AAFC 390E

* remotes/jnsnow/tags/ide-pull-request: (35 commits)
  ahci: fix sdb fis semantics
  qtest/ahci: halted ncq migration test
  ahci: Do not map cmd_fis to generate response
  ahci: ncq migration
  ahci: add get_cmd_header helper
  ahci: add cmd header to ncq transfer state
  qtest/ahci: halted NCQ test
  ahci: correct ncq sector count
  ahci: correct types in NCQTransferState
  ahci: add rwerror=stop support for ncq
  ahci: factor ncq_finish out of ncq_cb
  ahci: refactor process_ncq_command
  ahci: assert is_ncq for process_ncq
  ahci: stash ncq command
  ide: add limit to .prepare_buf()
  qtest/ahci: ncq migration test
  qtest/ahci: simple ncq data test
  libqos/ahci: Force all NCQ commands to be LBA48
  libqos/ahci: set the NCQ tag on command_commit
  libqos/ahci: adjust expected NCQ interrupts
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 16 insertions, 5 deletions

diff --git a/hw/ide/pci.c b/hw/ide/pci.c
index 4afd0cfe8c..d31ff885b7 100644
--- a/hw/ide/pci.c
+++ b/hw/ide/pci.c
@@ -53,10 +53,14 @@ static void bmdma_start_dma(IDEDMA *dma, IDEState *s,
 }
 
 /**
- * Return the number of bytes successfully prepared.
- * -1 on error.
+ * Prepare an sglist based on available PRDs.
+ * @limit: How many bytes to prepare total.
+ *
+ * Returns the number of bytes prepared, -1 on error.
+ * IDEState.io_buffer_size will contain the number of bytes described
+ * by the PRDs, whether or not we added them to the sglist.
  */
-static int32_t bmdma_prepare_buf(IDEDMA *dma, int is_write)
+static int32_t bmdma_prepare_buf(IDEDMA *dma, int32_t limit)
 {
     BMDMAState *bm = DO_UPCAST(BMDMAState, dma, dma);
     IDEState *s = bmdma_active_if(bm);
@@ -75,7 +79,7 @@ static int32_t bmdma_prepare_buf(IDEDMA *dma, int is_write)
             /* end of table (with a fail safe of one page) */
             if (bm->cur_prd_last ||
                 (bm->cur_addr - bm->addr) >= BMDMA_PAGE_SIZE) {
-                return s->io_buffer_size;
+                return s->sg.size;
             }
             pci_dma_read(pci_dev, bm->cur_addr, &prd, 8);
             bm->cur_addr += 8;
@@ -90,7 +94,14 @@ static int32_t bmdma_prepare_buf(IDEDMA *dma, int is_write)
         }
         l = bm->cur_prd_len;
         if (l > 0) {
-            qemu_sglist_add(&s->sg, bm->cur_prd_addr, l);
+            uint64_t sg_len;
+
+            /* Don't add extra bytes to the SGList; consume any remaining
+             * PRDs from the guest, but ignore them. */
+            sg_len = MIN(limit - s->sg.size, bm->cur_prd_len);
+            if (sg_len) {
+                qemu_sglist_add(&s->sg, bm->cur_prd_addr, sg_len);
+            }
 
             /* Note: We limit the max transfer to be 2GiB.
              * This should accommodate the largest ATA transaction