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drm/i915: Force VT'd workarounds when running as a guest OS

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If i915.ko is being used as a passthrough device, it does not know if
the host is using intel_iommu. Mixing the iommu and gfx causes a few
issues (such as scanout overfetch) which we need to workaround inside
the driver, so if we detect we are running under a hypervisor, also
assume the device access is being virtualised.

Reported-by: Stefan Fritsch <sf@sfritsch.de>
Suggested-by: Stefan Fritsch <sf@sfritsch.de>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Stefan Fritsch <sf@sfritsch.de>
Cc: stable@vger.kernel.org
Tested-by: Stefan Fritsch <sf@sfritsch.de>
Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201019101523.4145-1-chris@chris-wilson.co.uk
(cherry picked from commit f566fdcd6cc49a9d5b5d782f56e3e7cb243f01b8)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
This commit is contained in:
Chris Wilson 2020-10-19 11:15:23 +01:00 committed by Rodrigo Vivi
parent 3da3c5c1c9
commit 8195400f7e
1 changed files with 5 additions and 1 deletions
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6
drivers/gpu/drm/i915/i915_drv.h
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@ -33,6 +33,8 @@
#include <uapi/drm/i915_drm.h>
#include <uapi/drm/drm_fourcc.h>
#include <asm/hypervisor.h>
#include <linux/io-mapping.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-bit.h>
@ -1760,7 +1762,9 @@ static inline bool intel_vtd_active(void)
if (intel_iommu_gfx_mapped)
return true;
#endif
return false;
/* Running as a guest, we assume the host is enforcing VT'd */
return !hypervisor_is_type(X86_HYPER_NATIVE);
}
static inline bool intel_scanout_needs_vtd_wa(struct drm_i915_private *dev_priv)