From 8195400f7ea95399f721ad21f4d663a62c65036f Mon Sep 17 00:00:00 2001

From: Chris Wilson <chris@chris-wilson.co.uk>

Date: Mon, 19 Oct 2020 11:15:23 +0100

Subject: [PATCH] drm/i915: Force VT'd workarounds when running as a guest OS

Git-commit: 8195400f7ea95399f721ad21f4d663a62c65036f

Patch-mainline: v5.10-rc1

No-fix: f566fdcd6cc49a9d5b5d782f56e3e7cb243f01b8

References: git-fixes

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>

Acked-by: Takashi Iwai <tiwai@suse.de>

---

 drivers/gpu/drm/i915/i915_drv.h | 6 +++++-

 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h

index eef9a821c49c..8426d5974669 100644

--- a/drivers/gpu/drm/i915/i915_drv.h

+++ b/drivers/gpu/drm/i915/i915_drv.h

@@ -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)

-- 

2.16.4