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authorDavid Gibson <david@gibson.dropbear.id.au>2012-09-26 12:59:31 +1000
committerGerd Hoffmann <kraxel@redhat.com>2012-09-26 09:24:42 +0200
commit39c138c8420f51a7da7b35233a8d7400a0b589ac (patch)
treeaaa8f11a1095f084741ce55b2dc3539e85864218 /hw
parent8b626aa7841ef79b70066c880b3b6c29496797af (diff)
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usb: Fix usb_packet_map() in the presence of IOMMUs
With the IOMMU infrastructure introduced before 1.2, we need to use dma_memory_map() to obtain a qemu pointer to memory from an IO bus address. However, dma_memory_map() alters the given length to reflect the length over which the used DMA translation is valid - which could be either more or less than the requested length. usb_packet_map() does not correctly handle these cases, simply failing if dma_memory_map() alters the requested length. If dma_memory_map() increased the length, we just need to use the requested length for the qemu_iovec_add(). However, if it decreased the length, it means that a single DMA translation is not valid for the whole sglist element, and so we need to loop, splitting it up into multiple iovec entries for each piece with a DMA translation (in practice >2 pieces is unlikely). This patch implements the correct behaviour Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Diffstat (limited to 'hw')
-rw-r--r--hw/usb/libhw.c24
1 files changed, 15 insertions, 9 deletions
diff --git a/hw/usb/libhw.c b/hw/usb/libhw.c
index c0de30e..703e2d2 100644
--- a/hw/usb/libhw.c
+++ b/hw/usb/libhw.c
@@ -28,19 +28,25 @@ int usb_packet_map(USBPacket *p, QEMUSGList *sgl)
{
DMADirection dir = (p->pid == USB_TOKEN_IN) ?
DMA_DIRECTION_FROM_DEVICE : DMA_DIRECTION_TO_DEVICE;
- dma_addr_t len;
void *mem;
int i;
for (i = 0; i < sgl->nsg; i++) {
- len = sgl->sg[i].len;
- mem = dma_memory_map(sgl->dma, sgl->sg[i].base, &len, dir);
- if (!mem) {
- goto err;
- }
- qemu_iovec_add(&p->iov, mem, len);
- if (len != sgl->sg[i].len) {
- goto err;
+ dma_addr_t base = sgl->sg[i].base;
+ dma_addr_t len = sgl->sg[i].len;
+
+ while (len) {
+ dma_addr_t xlen = len;
+ mem = dma_memory_map(sgl->dma, sgl->sg[i].base, &xlen, dir);
+ if (!mem) {
+ goto err;
+ }
+ if (xlen > len) {
+ xlen = len;
+ }
+ qemu_iovec_add(&p->iov, mem, xlen);
+ len -= xlen;
+ base += xlen;
}
}
return 0;