qemu-e2k/hw/vfio
Jose Ricardo Ziviani 15126cba86 vfio: Set MemoryRegionOps:max_access_size and min_access_size
Sets valid.max_access_size and valid.min_access_size to ensure safe
8-byte accesses to vfio. Today, 8-byte accesses are broken into pairs
of 4-byte calls that goes unprotected:

qemu_mutex_lock locked mutex 0x10905ad8
  vfio_region_write  (0001:03:00.0:region1+0xc0, 0x2020c, 4)
qemu_mutex_unlock unlocked mutex 0x10905ad8
qemu_mutex_lock locked mutex 0x10905ad8
  vfio_region_write  (0001:03:00.0:region1+0xc4, 0xa0000, 4)
qemu_mutex_unlock unlocked mutex 0x10905ad8

which occasionally leads to:

qemu_mutex_lock locked mutex 0x10905ad8
  vfio_region_write  (0001:03:00.0:region1+0xc0, 0x2030c, 4)
qemu_mutex_unlock unlocked mutex 0x10905ad8
qemu_mutex_lock locked mutex 0x10905ad8
  vfio_region_write  (0001:03:00.0:region1+0xc0, 0x1000c, 4)
qemu_mutex_unlock unlocked mutex 0x10905ad8
qemu_mutex_lock locked mutex 0x10905ad8
  vfio_region_write  (0001:03:00.0:region1+0xc4, 0xb0000, 4)
qemu_mutex_unlock unlocked mutex 0x10905ad8
qemu_mutex_lock locked mutex 0x10905ad8
  vfio_region_write  (0001:03:00.0:region1+0xc4, 0xa0000, 4)
qemu_mutex_unlock unlocked mutex 0x10905ad8

causing strange errors in guest OS. With this patch, such accesses
are protected by the same lock guard:

qemu_mutex_lock locked mutex 0x10905ad8
vfio_region_write  (0001:03:00.0:region1+0xc0, 0x2000c, 4)
vfio_region_write  (0001:03:00.0:region1+0xc4, 0xb0000, 4)
qemu_mutex_unlock unlocked mutex 0x10905ad8

This happens because the 8-byte write should be broken into 4-byte
writes by memory.c:access_with_adjusted_size() in order to be under
the same lock. Today, it's done in exec.c:address_space_write_continue()
which was able to handle only 4 bytes due to a zero'ed
valid.max_access_size (see exec.c:memory_access_size()).

Signed-off-by: Jose Ricardo Ziviani <joserz@linux.vnet.ibm.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2017-05-03 14:52:34 -06:00
..
amd-xgbe.c
calxeda-xgmac.c
common.c vfio: Set MemoryRegionOps:max_access_size and min_access_size 2017-05-03 14:52:34 -06:00
Makefile.objs hw/vfio: Add CONFIG switches for calxeda-xgmac and amd-xgbe 2017-02-10 13:12:03 -07:00
pci-quirks.c vfio/pci-quirks: Exclude non-ioport BAR from NVIDIA quirk 2017-04-06 16:03:26 -06:00
pci.c vfio/pci: Improve extended capability comments, skip masked caps 2017-02-22 13:19:58 -07:00
pci.h
platform.c
spapr.c
trace-events vfio: trace map/unmap for notify as well 2017-02-17 21:52:31 +02:00