Re: [PATCH v5 5/9] iommu/arm-smmu-v3: Refactor write_ctx_desc
From: Will Deacon <will@kernel.org>
Date: 2023-08-09 13:50:09
Also in:
linux-iommu, lkml
On Wed, Aug 09, 2023 at 01:12:01AM +0800, Michael Shavit wrote:
quoted hunk ↗ jump to hunk
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c index 968559d625c40..e3992a0c16377 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c@@ -37,6 +37,24 @@ struct arm_smmu_bond { static DEFINE_MUTEX(sva_lock); +static int arm_smmu_write_ctx_desc_devices(struct arm_smmu_domain *smmu_domain, + int ssid, + struct arm_smmu_ctx_desc *cd) +{ + struct arm_smmu_master *master; + unsigned long flags; + int ret; + + spin_lock_irqsave(&smmu_domain->devices_lock, flags); + list_for_each_entry(master, &smmu_domain->devices, domain_head) { + ret = arm_smmu_write_ctx_desc(master, ssid, cd); + if (ret) + break; + } + spin_unlock_irqrestore(&smmu_domain->devices_lock, flags); + return ret; +} + /* * Check if the CPU ASID is available on the SMMU side. If a private context * descriptor is using it, try to replace it.@@ -80,7 +98,7 @@ arm_smmu_share_asid(struct mm_struct *mm, u16 asid) * be some overlap between use of both ASIDs, until we invalidate the * TLB. */ - arm_smmu_write_ctx_desc(smmu_domain, 0, cd); + arm_smmu_write_ctx_desc_devices(smmu_domain, 0, cd); /* Invalidate TLB entries previously associated with that context */ arm_smmu_tlb_inv_asid(smmu, asid);@@ -222,7 +240,7 @@ static void arm_smmu_mm_release(struct mmu_notifier *mn, struct mm_struct *mm) * DMA may still be running. Keep the cd valid to avoid C_BAD_CD events, * but disable translation. */ - arm_smmu_write_ctx_desc(smmu_domain, mm->pasid, &quiet_cd); + arm_smmu_write_ctx_desc_devices(smmu_domain, mm->pasid, &quiet_cd); arm_smmu_tlb_inv_asid(smmu_domain->smmu, smmu_mn->cd->asid); arm_smmu_atc_inv_domain(smmu_domain, mm->pasid, 0, 0);@@ -279,9 +297,11 @@ arm_smmu_mmu_notifier_get(struct arm_smmu_domain *smmu_domain, goto err_free_cd; } - ret = arm_smmu_write_ctx_desc(smmu_domain, mm->pasid, cd); - if (ret) + ret = arm_smmu_write_ctx_desc_devices(smmu_domain, mm->pasid, cd); + if (ret) { + arm_smmu_write_ctx_desc_devices(smmu_domain, mm->pasid, NULL);
Why is it safe to drop the lock between these two calls?
quoted hunk ↗ jump to hunk
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 c01023404c26c..34bd7815aeb8e 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c@@ -971,14 +971,12 @@ void arm_smmu_tlb_inv_asid(struct arm_smmu_device *smmu, u16 asid) arm_smmu_cmdq_issue_cmd_with_sync(smmu, &cmd); } -static void arm_smmu_sync_cd(struct arm_smmu_domain *smmu_domain, +static void arm_smmu_sync_cd(struct arm_smmu_master *master, int ssid, bool leaf) { size_t i; - unsigned long flags; - struct arm_smmu_master *master; struct arm_smmu_cmdq_batch cmds; - struct arm_smmu_device *smmu = smmu_domain->smmu; + struct arm_smmu_device *smmu = master->smmu; struct arm_smmu_cmdq_ent cmd = { .opcode = CMDQ_OP_CFGI_CD, .cfgi = {@@ -988,15 +986,10 @@ static void arm_smmu_sync_cd(struct arm_smmu_domain *smmu_domain, }; cmds.num = 0; - - spin_lock_irqsave(&smmu_domain->devices_lock, flags);
Since you're dropping this and relying on the lock being taken higher up callstack, can we add a lockdep assertion that we do actually hold the devices_lock, please? Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel