On Wed, Jul 7 2021 at 21:57:05 +0400, Rob Clark robdclark@gmail.com wrote:

From: Rob Clark robdclark@chromium.org

It turns out that when the display is enabled by the bootloader, we can get some transient iommu faults from the display. Which doesn't go over too well when we install a fault handler that is gpu specific. To avoid this, defer installing the fault handler until we get around to setting up per-process pgtables (which is adreno_smmu specific). The arm-smmu fallback error reporting is sufficient for reporting display related faults (and in fact was all we had prior to f8f934c180f629bb927a04fd90d)

Reported-by: Dmitry Baryshkov dmitry.baryshkov@linaro.org Reported-by: Yassine Oudjana y.oudjana@protonmail.com Fixes: 2a574cc05d38 ("drm/msm: Improve the a6xx page fault handler") Signed-off-by: Rob Clark robdclark@chromium.org Tested-by: John Stultz john.stultz@linaro.org

---

drivers/gpu/drm/msm/msm_iommu.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/msm_iommu.c b/drivers/gpu/drm/msm/msm_iommu.c index eed2a762e9dd..bcaddbba564d 100644 --- a/drivers/gpu/drm/msm/msm_iommu.c +++ b/drivers/gpu/drm/msm/msm_iommu.c @@ -142,6 +142,9 @@ static const struct iommu_flush_ops null_tlb_ops = { .tlb_add_page = msm_iommu_tlb_add_page, };

+static int msm_fault_handler(struct iommu_domain *domain, struct device *dev,

• unsigned long iova, int flags, void *arg);
  

struct msm_mmu *msm_iommu_pagetable_create(struct msm_mmu *parent) { struct adreno_smmu_priv *adreno_smmu = dev_get_drvdata(parent->dev); @@ -157,6 +160,13 @@ struct msm_mmu *msm_iommu_pagetable_create(struct msm_mmu *parent) if (!ttbr1_cfg) return ERR_PTR(-ENODEV);

• /*

• * Defer setting the fault handler until we have a valid adreno_smmu
  

• * to avoid accidentially installing a GPU specific fault handler 
  

for

• * the display's iommu
  

• */
  

• iommu_set_fault_handler(iommu->domain, msm_fault_handler, iommu);
• pagetable = kzalloc(sizeof(*pagetable), GFP_KERNEL); if (!pagetable) return ERR_PTR(-ENOMEM);

@@ -300,7 +310,6 @@ struct msm_mmu *msm_iommu_new(struct device *dev, struct iommu_domain *domain)

iommu->domain = domain; msm_mmu_init(&iommu->base, dev, &funcs, MSM_MMU_IOMMU);

• iommu_set_fault_handler(domain, msm_fault_handler, iommu);

  atomic_set(&iommu->pagetables, 0);

-- 2.31.1

Tested-by: Yassine Oudjana y.oudjana@protonmail.com

On Wed 07 Jul 11:01 PDT 2021, Rob Clark wrote:

From: Rob Clark robdclark@chromium.org

It turns out that when the display is enabled by the bootloader, we can get some transient iommu faults from the display. Which doesn't go over too well when we install a fault handler that is gpu specific. To avoid this, defer installing the fault handler until we get around to setting up per-process pgtables (which is adreno_smmu specific). The arm-smmu fallback error reporting is sufficient for reporting display related faults (and in fact was all we had prior to f8f934c180f629bb927a04fd90d)

Reported-by: Dmitry Baryshkov dmitry.baryshkov@linaro.org Reported-by: Yassine Oudjana y.oudjana@protonmail.com Fixes: 2a574cc05d38 ("drm/msm: Improve the a6xx page fault handler") Signed-off-by: Rob Clark robdclark@chromium.org Tested-by: John Stultz john.stultz@linaro.org

Reviewed-by: Bjorn Andersson bjorn.andersson@linaro.org

Regards, Bjorn

---

drivers/gpu/drm/msm/msm_iommu.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/msm_iommu.c b/drivers/gpu/drm/msm/msm_iommu.c index eed2a762e9dd..bcaddbba564d 100644 --- a/drivers/gpu/drm/msm/msm_iommu.c +++ b/drivers/gpu/drm/msm/msm_iommu.c @@ -142,6 +142,9 @@ static const struct iommu_flush_ops null_tlb_ops = { .tlb_add_page = msm_iommu_tlb_add_page, };

+static int msm_fault_handler(struct iommu_domain *domain, struct device *dev,

• unsigned long iova, int flags, void *arg);
  

struct msm_mmu *msm_iommu_pagetable_create(struct msm_mmu *parent) { struct adreno_smmu_priv *adreno_smmu = dev_get_drvdata(parent->dev); @@ -157,6 +160,13 @@ struct msm_mmu *msm_iommu_pagetable_create(struct msm_mmu *parent) if (!ttbr1_cfg) return ERR_PTR(-ENODEV);

• /*

• * Defer setting the fault handler until we have a valid adreno_smmu
  

• * to avoid accidentially installing a GPU specific fault handler for
  

• * the display's iommu
  

• */
  

• iommu_set_fault_handler(iommu->domain, msm_fault_handler, iommu);
• pagetable = kzalloc(sizeof(*pagetable), GFP_KERNEL); if (!pagetable) return ERR_PTR(-ENOMEM);

@@ -300,7 +310,6 @@ struct msm_mmu *msm_iommu_new(struct device *dev, struct iommu_domain *domain)

iommu->domain = domain; msm_mmu_init(&iommu->base, dev, &funcs, MSM_MMU_IOMMU);

• iommu_set_fault_handler(domain, msm_fault_handler, iommu);

  atomic_set(&iommu->pagetables, 0);

-- 2.31.1