drm/i915: Do not enable movntdqa optimization in hypervisor guest
authorChangbin Du <changbin.du@intel.com>
Fri, 22 Dec 2017 06:31:49 +0000 (14:31 +0800)
committerChris Wilson <chris@chris-wilson.co.uk>
Fri, 22 Dec 2017 11:12:15 +0000 (11:12 +0000)
commit219af7331f37e0e803688f6c5f7d29bc6204e88e
tree3e40004026527c3ba6d285cd7096513fd1590a30
parent27d558a1a0ab07bcf15b3ca7e816f9ed2f558e59
drm/i915: Do not enable movntdqa optimization in hypervisor guest

Our QA reported a problem caused by movntdqa instructions. Currently,
the KVM hypervisor doesn't support VEX-prefix instructions emulation.
If users passthrough a GPU to guest with vfio option 'x-no-mmap=on',
then all access to the BARs will be trapped and emulated. The KVM
hypervisor would raise an inertal error to qemu which cause the guest
killed. (Since 'movntdqa' ins is not supported.)

This patch try not to enable movntdqa optimization if the driver is
running in hypervisor guest.

Signed-off-by: Changbin Du <changbin.du@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1513924309-3113-1-git-send-email-changbin.du@intel.com
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
drivers/gpu/drm/i915/i915_memcpy.c