On 10/11/2021 07:12, Lu Baolu wrote:
Hi Tvrtko,
On 2021/11/9 20:17, Tvrtko Ursulin wrote:
From: Tvrtko Ursulin<tvrtko.ursulin@xxxxxxxxx>
On igfx + dgfx setups, it appears that intel_iommu=igfx_off option only
disables the igfx iommu. Stop relying on global intel_iommu_gfx_mapped
and probe presence of iommu domain per device to accurately reflect its
status.
Signed-off-by: Tvrtko Ursulin<tvrtko.ursulin@xxxxxxxxx>
Cc: Lu Baolu<baolu.lu@xxxxxxxxxxxxxxx>
---
Baolu, is my understanding here correct? Maybe I am confused by both
intel_iommu_gfx_mapped and dmar_map_gfx being globals in the intel_iommu
driver. But it certainly appears the setup can assign some iommu ops (and
assign the discrete i915 to iommu group) when those two are set to off.
diff --git a/drivers/gpu/drm/i915/i915_drv.h
b/drivers/gpu/drm/i915/i915_drv.h
index e967cd08f23e..9fb38a54f1fe 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1763,26 +1763,27 @@ static inline bool run_as_guest(void)
#define HAS_D12_PLANE_MINIMIZATION(dev_priv) (IS_ROCKETLAKE(dev_priv)
|| \
IS_ALDERLAKE_S(dev_priv))
-static inline bool intel_vtd_active(void)
+static inline bool intel_vtd_active(struct drm_i915_private *i915)
{
-#ifdef CONFIG_INTEL_IOMMU
- if (intel_iommu_gfx_mapped)
+ if (iommu_get_domain_for_dev(i915->drm.dev))
return true;
-#endif
/* Running as a guest, we assume the host is enforcing VT'd */
return run_as_guest();
}
Have you verified this change? I am afraid that
iommu_get_domain_for_dev() always gets a valid iommu domain even
intel_iommu_gfx_mapped == 0.
Yes it seems to work as is:
default:
# grep -i iommu /sys/kernel/debug/dri/*/i915_capabilities
/sys/kernel/debug/dri/0/i915_capabilities:iommu: enabled
/sys/kernel/debug/dri/1/i915_capabilities:iommu: enabled
intel_iommu=igfx_off:
# grep -i iommu /sys/kernel/debug/dri/*/i915_capabilities
/sys/kernel/debug/dri/0/i915_capabilities:iommu: disabled
/sys/kernel/debug/dri/1/i915_capabilities:iommu: enabled
On my system dri device 0 is integrated graphics and 1 is discrete.
Regards,
Tvrtko
A possible way could look like this:
static bool intel_vtd_active(struct drm_i915_private *i915)
{
struct iommu_domain *domain;
domain = iommu_get_domain_for_dev(i915->drm.dev);
if (domain && (domain->type & __IOMMU_DOMAIN_PAGING))
return true;
... ...
}
Actually I don't like this either since it checks the domain->type out
of the iommu subsystem. We could refactor this later by export an iommu
interface for this check.
Best regards,
baolu
