drm/i915/vgpu: Disallow loading on old vGPU hosts

Since commit fd8526e50902 ("drm/i915/execlists: Trust the CSB") we
actually broke the force-mmio mode for our execlists implementation. No
one noticed, so ergo no one is actually using an old vGPU host (where we
required the older method) and so can simply remove the broken support.

v2: csb_read can go as well (Mika)

Reported-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Fixes: fd8526e50902 ("drm/i915/execlists: Trust the CSB")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181130125954.11924-1-chris@chris-wilson.co.uk

1 files changed, 14 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index e39016713464..3e5e2efce670 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1384,6 +1384,20 @@ static int i915_driver_init_hw(struct drm_i915_private *dev_priv)
 		}
 	}
 
+	if (HAS_EXECLISTS(dev_priv)) {
+		/*
+		 * Older GVT emulation depends upon intercepting CSB mmio,
+		 * which we no longer use, preferring to use the HWSP cache
+		 * instead.
+		 */
+		if (intel_vgpu_active(dev_priv) &&
+		    !intel_vgpu_has_hwsp_emulation(dev_priv)) {
+			i915_report_error(dev_priv,
+					  "old vGPU host found, support for HWSP emulation required\n");
+			return -ENXIO;
+		}
+	}
+
 	intel_sanitize_options(dev_priv);
 
 	i915_perf_init(dev_priv);