| Message ID | 20240717072145.107412-1-amhetre@nvidia.com |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | iommu: arm-smmu: Fix Tegra workaround for PAGE_SIZE mappings | expand |
On Wed, Jul 17, 2024 at 07:21:45AM +0000, Ashish Mhetre wrote: > PAGE_SIZE can be 16KB for Tegra which is not supported by MMU-500 on > both Tegra194 and Tegra234. So, use 4KB mappings when PAGE_SIZE is 16KB. > > Signed-off-by: Ashish Mhetre <amhetre@nvidia.com> > --- > drivers/iommu/arm/arm-smmu/arm-smmu-nvidia.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-nvidia.c b/drivers/iommu/arm/arm-smmu/arm-smmu-nvidia.c > index 4b2994b6126d..bb621a94f6fe 100644 > --- a/drivers/iommu/arm/arm-smmu/arm-smmu-nvidia.c > +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-nvidia.c > @@ -273,11 +273,12 @@ static int nvidia_smmu_init_context(struct arm_smmu_domain *smmu_domain, > * release of PMD entry and avoid translations seeing stale PMD entry in > * walk cache. > * Fix this by limiting the page mappings to PAGE_SIZE on Tegra194 and > - * Tegra234. > + * Tegra234. Use 4K page mappings if PAGE_SIZE is 16K as MMU500 doesn't > + * support it. > */ > if (of_device_is_compatible(np, "nvidia,tegra234-smmu") || > of_device_is_compatible(np, "nvidia,tegra194-smmu")) { > - smmu->pgsize_bitmap = PAGE_SIZE; > + smmu->pgsize_bitmap = (PAGE_SIZE == SZ_16K) ? SZ_4K : PAGE_SIZE; Perhaps it would be more robust to do a read-modify-write of the pgsize_bitmap, preserving all the page-sizes that are <= PAGE_SIZE (i.e. and it with something like GENMASK(PAGE_SHIFT, 0)? Will
On 7/23/2024 9:41 PM, Will Deacon wrote: > External email: Use caution opening links or attachments > > > On Wed, Jul 17, 2024 at 07:21:45AM +0000, Ashish Mhetre wrote: >> PAGE_SIZE can be 16KB for Tegra which is not supported by MMU-500 on >> both Tegra194 and Tegra234. So, use 4KB mappings when PAGE_SIZE is 16KB. >> >> Signed-off-by: Ashish Mhetre <amhetre@nvidia.com> >> --- >> drivers/iommu/arm/arm-smmu/arm-smmu-nvidia.c | 5 +++-- >> 1 file changed, 3 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-nvidia.c b/drivers/iommu/arm/arm-smmu/arm-smmu-nvidia.c >> index 4b2994b6126d..bb621a94f6fe 100644 >> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-nvidia.c >> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-nvidia.c >> @@ -273,11 +273,12 @@ static int nvidia_smmu_init_context(struct arm_smmu_domain *smmu_domain, >> * release of PMD entry and avoid translations seeing stale PMD entry in >> * walk cache. >> * Fix this by limiting the page mappings to PAGE_SIZE on Tegra194 and >> - * Tegra234. >> + * Tegra234. Use 4K page mappings if PAGE_SIZE is 16K as MMU500 doesn't >> + * support it. >> */ >> if (of_device_is_compatible(np, "nvidia,tegra234-smmu") || >> of_device_is_compatible(np, "nvidia,tegra194-smmu")) { >> - smmu->pgsize_bitmap = PAGE_SIZE; >> + smmu->pgsize_bitmap = (PAGE_SIZE == SZ_16K) ? SZ_4K : PAGE_SIZE; > Perhaps it would be more robust to do a read-modify-write of the > pgsize_bitmap, preserving all the page-sizes that are <= PAGE_SIZE (i.e. > and it with something like GENMASK(PAGE_SHIFT, 0)? > > Will Thanks for the review Will. Yes, that will be a better approach as pgsize_bitmap will never be with 16K granularity for Tegra. I will send new version with this update.
diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-nvidia.c b/drivers/iommu/arm/arm-smmu/arm-smmu-nvidia.c index 4b2994b6126d..bb621a94f6fe 100644 --- a/drivers/iommu/arm/arm-smmu/arm-smmu-nvidia.c +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-nvidia.c @@ -273,11 +273,12 @@ static int nvidia_smmu_init_context(struct arm_smmu_domain *smmu_domain, * release of PMD entry and avoid translations seeing stale PMD entry in * walk cache. * Fix this by limiting the page mappings to PAGE_SIZE on Tegra194 and - * Tegra234. + * Tegra234. Use 4K page mappings if PAGE_SIZE is 16K as MMU500 doesn't + * support it. */ if (of_device_is_compatible(np, "nvidia,tegra234-smmu") || of_device_is_compatible(np, "nvidia,tegra194-smmu")) { - smmu->pgsize_bitmap = PAGE_SIZE; + smmu->pgsize_bitmap = (PAGE_SIZE == SZ_16K) ? SZ_4K : PAGE_SIZE; pgtbl_cfg->pgsize_bitmap = smmu->pgsize_bitmap; }
PAGE_SIZE can be 16KB for Tegra which is not supported by MMU-500 on both Tegra194 and Tegra234. So, use 4KB mappings when PAGE_SIZE is 16KB. Signed-off-by: Ashish Mhetre <amhetre@nvidia.com> --- drivers/iommu/arm/arm-smmu/arm-smmu-nvidia.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)