On 10/11/2021 07:12, Lu Baolu wrote:
Hi Tvrtko,
On 2021/11/9 20:17, Tvrtko Ursulin wrote:
From: Tvrtko Ursulintvrtko.ursulin@intel.com
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 Ursulintvrtko.ursulin@intel.com Cc: Lu Baolubaolu.lu@linux.intel.com
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