xemu/hw/usb/libhw.c
David Gibson 39c138c842 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>
2012-09-26 09:24:42 +02:00

71 lines
2.3 KiB
C

/*
* QEMU USB emulation, libhw bits.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu-common.h"
#include "cpu-common.h"
#include "hw/usb.h"
#include "dma.h"
int usb_packet_map(USBPacket *p, QEMUSGList *sgl)
{
DMADirection dir = (p->pid == USB_TOKEN_IN) ?
DMA_DIRECTION_FROM_DEVICE : DMA_DIRECTION_TO_DEVICE;
void *mem;
int i;
for (i = 0; i < sgl->nsg; i++) {
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;
err:
usb_packet_unmap(p, sgl);
return -1;
}
void usb_packet_unmap(USBPacket *p, QEMUSGList *sgl)
{
DMADirection dir = (p->pid == USB_TOKEN_IN) ?
DMA_DIRECTION_FROM_DEVICE : DMA_DIRECTION_TO_DEVICE;
int i;
for (i = 0; i < p->iov.niov; i++) {
dma_memory_unmap(sgl->dma, p->iov.iov[i].iov_base,
p->iov.iov[i].iov_len, dir,
p->iov.iov[i].iov_len);
}
}