From d2e053d73247b68144c7f44d002ebf56acaf2d48 Mon Sep 17 00:00:00 2001 From: Jason Gunthorpe Date: Mon, 26 Feb 2024 13:07:19 -0400 Subject: iommu/arm-smmu-v3: Put writing the context descriptor in the right order Get closer to the IOMMU API ideal that changes between domains can be hitless. The ordering for the CD table entry is not entirely clean from this perspective. When switching away from a STE with a CD table programmed in it we should write the new STE first, then clear any old data in the CD entry. If we are programming a CD table for the first time to a STE then the CD entry should be programmed before the STE is loaded. If we are replacing a CD table entry when the STE already points at the CD entry then we just need to do the make/break sequence. Lift this code out of arm_smmu_detach_dev() so it can all be sequenced properly. The only other caller is arm_smmu_release_device() and it is going to free the cdtable anyhow, so it doesn't matter what is in it. Reviewed-by: Michael Shavit Reviewed-by: Nicolin Chen Reviewed-by: Mostafa Saleh Tested-by: Shameer Kolothum Tested-by: Nicolin Chen Tested-by: Moritz Fischer Signed-off-by: Jason Gunthorpe Link: https://lore.kernel.org/r/8-v6-96275f25c39d+2d4-smmuv3_newapi_p1_jgg@nvidia.com Signed-off-by: Will Deacon --- drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 29 ++++++++++++++++++++--------- 1 file changed, 20 insertions(+), 9 deletions(-) (limited to 'drivers/iommu') diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c index 597a8c5f9658..ec05743ee208 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c @@ -2522,14 +2522,6 @@ static void arm_smmu_detach_dev(struct arm_smmu_master *master) master->domain = NULL; master->ats_enabled = false; - /* - * Clearing the CD entry isn't strictly required to detach the domain - * since the table is uninstalled anyway, but it helps avoid confusion - * in the call to arm_smmu_write_ctx_desc on the next attach (which - * expects the entry to be empty). - */ - if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1 && master->cd_table.cdtab) - arm_smmu_write_ctx_desc(master, IOMMU_NO_PASID, NULL); } static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev) @@ -2606,6 +2598,17 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev) master->domain = NULL; goto out_list_del; } + } else { + /* + * arm_smmu_write_ctx_desc() relies on the entry being + * invalid to work, clear any existing entry. + */ + ret = arm_smmu_write_ctx_desc(master, IOMMU_NO_PASID, + NULL); + if (ret) { + master->domain = NULL; + goto out_list_del; + } } ret = arm_smmu_write_ctx_desc(master, IOMMU_NO_PASID, &smmu_domain->cd); @@ -2615,15 +2618,23 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev) } arm_smmu_make_cdtable_ste(&target, master); + arm_smmu_install_ste_for_dev(master, &target); break; case ARM_SMMU_DOMAIN_S2: arm_smmu_make_s2_domain_ste(&target, master, smmu_domain); + arm_smmu_install_ste_for_dev(master, &target); + if (master->cd_table.cdtab) + arm_smmu_write_ctx_desc(master, IOMMU_NO_PASID, + NULL); break; case ARM_SMMU_DOMAIN_BYPASS: arm_smmu_make_bypass_ste(&target); + arm_smmu_install_ste_for_dev(master, &target); + if (master->cd_table.cdtab) + arm_smmu_write_ctx_desc(master, IOMMU_NO_PASID, + NULL); break; } - arm_smmu_install_ste_for_dev(master, &target); arm_smmu_enable_ats(master); goto out_unlock; -- cgit v1.2.3