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path: root/drivers/gpu/drm/i915/i915_memcpy.c
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2017-12-22drm/i915: Do not enable movntdqa optimization in hypervisor guestChangbin Du
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>
2016-08-17drm/i915: Mark the static key for movntqda as staticChris Wilson
Silence sparse who warns that the global variable is not declared static. Fixes: 0b1de5d58e19 ("drm/i915: Use SSE4.1 movntdqa to ...") Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Akash Goel <akash.goel@intel.com> Cc: Damien Lespiau <damien.lespiau@intel.com> Cc: Mika Kuoppala <mika.kuoppala@intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1471432146-5196-1-git-send-email-chris@chris-wilson.co.uk Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
2016-08-12drm/i915: Use SSE4.1 movntdqa to accelerate reads from WC memoryChris Wilson
This patch provides the infrastructure for performing a 16-byte aligned read from WC memory using non-temporal instructions introduced with sse4.1. Using movntdqa we can bypass the CPU caches and read directly from memory and ignoring the page attributes set on the CPU PTE i.e. negating the impact of an otherwise UC access. Copying using movntdqa from WC is almost as fast as reading from WB memory, modulo the possibility of both hitting the CPU cache or leaving the data in the CPU cache for the next consumer. (The CPU cache itself my be flushed for the region of the movntdqa and on later access the movntdqa reads from a separate internal buffer for the cacheline.) The write back to the memory is however cached. This will be used in later patches to accelerate accessing WC memory. v2: Report whether the accelerated copy is successful/possible. v3: Function alignment override was only necessary when using the function target("sse4.1") - which is not necessary for emitting movntdqa from __asm__. v4: Improve notes on CPU cache behaviour vs non-temporal stores. v5: Fix byte offsets for unrolled moves. v6: Find all remaining typos of "movntqda", use kernel_fpu_begin. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Akash Goel <akash.goel@intel.com> Cc: Damien Lespiau <damien.lespiau@intel.com> Cc: Mika Kuoppala <mika.kuoppala@intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1471001999-17787-2-git-send-email-chris@chris-wilson.co.uk