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vfio_pci: Enable memory accesses before calling pci_map_rom

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[ Upstream commit 0cfd027be1d6def4a462cdc180c055143af24069 ]

pci_map_rom/pci_get_rom_size() performs memory access in the ROM.
In case the Memory Space accesses were disabled, readw() is likely
to trigger a synchronous external abort on some platforms.

In case memory accesses were disabled, re-enable them before the
call and disable them back again just after.

Fixes: 89e1f7d4c66d ("vfio: Add PCI device driver")
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Suggested-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Eric Auger 2019-02-15 17:16:06 +01:00 committed by prashantpaddune
parent 15e2533507
commit 71a5a54fbc
1 changed files with 17 additions and 8 deletions
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25
drivers/vfio/pci/vfio_pci.c
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@ -496,6 +496,7 @@ static long vfio_pci_ioctl(void *device_data,
{
void __iomem *io;
size_t size;
u16 orig_cmd;
info.offset = VFIO_PCI_INDEX_TO_OFFSET(info.index);
info.flags = 0;
@ -505,15 +506,23 @@ static long vfio_pci_ioctl(void *device_data,
if (!info.size)
break;
/* Is it really there? */
io = pci_map_rom(pdev, &size);
if (!io || !size) {
info.size = 0;
break;
}
pci_unmap_rom(pdev, io);
/*
* Is it really there? Enable memory decode for
* implicit access in pci_map_rom().
*/
pci_read_config_word(pdev, PCI_COMMAND, &orig_cmd);
pci_write_config_word(pdev, PCI_COMMAND,
orig_cmd | PCI_COMMAND_MEMORY);
info.flags = VFIO_REGION_INFO_FLAG_READ;
io = pci_map_rom(pdev, &size);
if (io) {
info.flags = VFIO_REGION_INFO_FLAG_READ;
pci_unmap_rom(pdev, io);
} else {
info.size = 0;
}
pci_write_config_word(pdev, PCI_COMMAND, orig_cmd);
break;
}
case VFIO_PCI_VGA_REGION_INDEX: