From: Jason Gunthorpe jgg@nvidia.com
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 mshavit@google.com Reviewed-by: Nicolin Chen nicolinc@nvidia.com Reviewed-by: Mostafa Saleh smostafa@google.com Tested-by: Shameer Kolothum shameerali.kolothum.thodi@huawei.com Tested-by: Nicolin Chen nicolinc@nvidia.com Tested-by: Moritz Fischer moritzf@google.com Signed-off-by: Jason Gunthorpe jgg@nvidia.com Link: https://lore.kernel.org/r/8-v6-96275f25c39d+2d4-smmuv3_newapi_p1_jgg@nvidia.... Signed-off-by: Will Deacon will@kernel.org Signed-off-by: Kunkun Jiang jiangkunkun@huawei.com --- drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 29 ++++++++++++++------- 1 file changed, 20 insertions(+), 9 deletions(-)
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 4792600019d1..3c36550ff050 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c @@ -2736,14 +2736,6 @@ 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) @@ -2820,6 +2812,17 @@ 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); @@ -2829,15 +2832,23 @@ 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;