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From: Jean-Philippe Brucker <jean-philippe@linaro.org>
To: iommu@lists.linux-foundation.org, devicetree@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org,
	linux-mm@kvack.org
Cc: fenghua.yu@intel.com, kevin.tian@intel.com, jgg@ziepe.ca,
	catalin.marinas@arm.com, robin.murphy@arm.com, hch@infradead.org,
	zhangfei.gao@linaro.org,
	Jean-Philippe Brucker <jean-philippe@linaro.org>,
	felix.kuehling@amd.com, will@kernel.org,
	christian.koenig@amd.com
Subject: [PATCH v7 11/24] iommu/arm-smmu-v3: Seize private ASID
Date: Tue, 19 May 2020 19:54:49 +0200	[thread overview]
Message-ID: <20200519175502.2504091-12-jean-philippe@linaro.org> (raw)
In-Reply-To: <20200519175502.2504091-1-jean-philippe@linaro.org>

The SMMU has a single ASID space, the union of shared and private ASID
sets. This means that the SMMU driver competes with the arch allocator
for ASIDs. Shared ASIDs are those of Linux processes, allocated by the
arch, and contribute in broadcast TLB maintenance. Private ASIDs are
allocated by the SMMU driver and used for "classic" map/unmap DMA. They
require command-queue TLB invalidations.

When we pin down an mm_context and get an ASID that is already in use by
the SMMU, it belongs to a private context. We used to simply abort the
bind, but this is unfair to users that would be unable to bind a few
seemingly random processes. Try to allocate a new private ASID for the
context, and make the old ASID shared.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
v6->v7: Replace context_lock spinlock with asid_lock mutex, remove
  GFP_ATOMIC changes, add comments about locking.
---
 drivers/iommu/arm-smmu-v3.c | 100 ++++++++++++++++++++++++++++--------
 1 file changed, 80 insertions(+), 20 deletions(-)

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 52cbdf08f5e2..403871d36438 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -733,6 +733,7 @@ struct arm_smmu_option_prop {
 };
 
 static DEFINE_XARRAY_ALLOC1(asid_xa);
+static DEFINE_MUTEX(asid_lock);
 static DEFINE_MUTEX(sva_lock);
 
 static struct arm_smmu_option_prop arm_smmu_options[] = {
@@ -1537,6 +1538,17 @@ static int arm_smmu_cmdq_batch_submit(struct arm_smmu_device *smmu,
 }
 
 /* Context descriptor manipulation functions */
+static void arm_smmu_tlb_inv_asid(struct arm_smmu_device *smmu, u16 asid)
+{
+	struct arm_smmu_cmdq_ent cmd = {
+		.opcode = CMDQ_OP_TLBI_NH_ASID,
+		.tlbi.asid = asid,
+	};
+
+	arm_smmu_cmdq_issue_cmd(smmu, &cmd);
+	arm_smmu_cmdq_issue_sync(smmu);
+}
+
 static void arm_smmu_sync_cd(struct arm_smmu_domain *smmu_domain,
 			     int ssid, bool leaf)
 {
@@ -1795,9 +1807,18 @@ static bool arm_smmu_free_asid(struct arm_smmu_ctx_desc *cd)
 	return free;
 }
 
+/*
+ * Try to reserve this ASID in the SMMU. If it is in use, try to steal it from
+ * the private entry. Careful here, we may be modifying the context tables of
+ * another SMMU!
+ */
 static struct arm_smmu_ctx_desc *arm_smmu_share_asid(u16 asid)
 {
+	int ret;
+	u32 new_asid;
 	struct arm_smmu_ctx_desc *cd;
+	struct arm_smmu_device *smmu;
+	struct arm_smmu_domain *smmu_domain;
 
 	cd = xa_load(&asid_xa, asid);
 	if (!cd)
@@ -1809,11 +1830,31 @@ static struct arm_smmu_ctx_desc *arm_smmu_share_asid(u16 asid)
 		return cd;
 	}
 
+	smmu_domain = container_of(cd, struct arm_smmu_domain, s1_cfg.cd);
+	smmu = smmu_domain->smmu;
+
+	ret = xa_alloc(&asid_xa, &new_asid, cd,
+		       XA_LIMIT(1, 1 << smmu->asid_bits), GFP_KERNEL);
+	if (ret)
+		return ERR_PTR(-ENOSPC);
+	/*
+	 * Race with unmap: TLB invalidations will start targeting the new ASID,
+	 * which isn't assigned yet. We'll do an invalidate-all on the old ASID
+	 * later, so it doesn't matter.
+	 */
+	cd->asid = new_asid;
+
 	/*
-	 * Ouch, ASID is already in use for a private cd.
-	 * TODO: seize it.
+	 * Update ASID and invalidate CD in all associated masters. There will
+	 * be some overlap between use of both ASIDs, until we invalidate the
+	 * TLB.
 	 */
-	return ERR_PTR(-EEXIST);
+	arm_smmu_write_ctx_desc(smmu_domain, 0, cd);
+
+	/* Invalidate TLB entries previously associated with that context */
+	arm_smmu_tlb_inv_asid(smmu, asid);
+
+	return NULL;
 }
 
 __maybe_unused
@@ -1839,7 +1880,20 @@ static struct arm_smmu_ctx_desc *arm_smmu_alloc_shared_cd(struct mm_struct *mm)
 
 	arm_smmu_init_cd(cd);
 
+	/*
+	 * Serialize against arm_smmu_domain_finalise_s1() and
+	 * arm_smmu_domain_free() as we might need to replace the private ASID
+	 * from an existing CD.
+	 */
+	mutex_lock(&asid_lock);
 	old_cd = arm_smmu_share_asid(asid);
+	if (!old_cd) {
+		ret = xa_insert(&asid_xa, asid, cd, GFP_KERNEL);
+		if (ret)
+			old_cd = ERR_PTR(ret);
+	}
+	mutex_unlock(&asid_lock);
+
 	if (IS_ERR(old_cd)) {
 		ret = PTR_ERR(old_cd);
 		goto err_free_cd;
@@ -1853,11 +1907,6 @@ static struct arm_smmu_ctx_desc *arm_smmu_alloc_shared_cd(struct mm_struct *mm)
 		return old_cd;
 	}
 
-	/* Fails if a private ASID has been allocated since we last checked */
-	ret = xa_insert(&asid_xa, asid, cd, GFP_KERNEL);
-	if (ret)
-		goto err_free_cd;
-
 	tcr = FIELD_PREP(CTXDESC_CD_0_TCR_T0SZ, 64ULL - VA_BITS) |
 	      FIELD_PREP(CTXDESC_CD_0_TCR_IRGN0, ARM_LPAE_TCR_RGN_WBWA) |
 	      FIELD_PREP(CTXDESC_CD_0_TCR_ORGN0, ARM_LPAE_TCR_RGN_WBWA) |
@@ -2401,15 +2450,6 @@ static void arm_smmu_tlb_inv_context(void *cookie)
 	struct arm_smmu_device *smmu = smmu_domain->smmu;
 	struct arm_smmu_cmdq_ent cmd;
 
-	if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1) {
-		cmd.opcode	= CMDQ_OP_TLBI_NH_ASID;
-		cmd.tlbi.asid	= smmu_domain->s1_cfg.cd.asid;
-		cmd.tlbi.vmid	= 0;
-	} else {
-		cmd.opcode	= CMDQ_OP_TLBI_S12_VMALL;
-		cmd.tlbi.vmid	= smmu_domain->s2_cfg.vmid;
-	}
-
 	/*
 	 * NOTE: when io-pgtable is in non-strict mode, we may get here with
 	 * PTEs previously cleared by unmaps on the current CPU not yet visible
@@ -2417,8 +2457,14 @@ static void arm_smmu_tlb_inv_context(void *cookie)
 	 * insertion to guarantee those are observed before the TLBI. Do be
 	 * careful, 007.
 	 */
-	arm_smmu_cmdq_issue_cmd(smmu, &cmd);
-	arm_smmu_cmdq_issue_sync(smmu);
+	if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1) {
+		arm_smmu_tlb_inv_asid(smmu, smmu_domain->s1_cfg.cd.asid);
+	} else {
+		cmd.opcode	= CMDQ_OP_TLBI_S12_VMALL;
+		cmd.tlbi.vmid	= smmu_domain->s2_cfg.vmid;
+		arm_smmu_cmdq_issue_cmd(smmu, &cmd);
+		arm_smmu_cmdq_issue_sync(smmu);
+	}
 	arm_smmu_atc_inv_domain(smmu_domain, 0, 0, 0);
 }
 
@@ -2602,9 +2648,15 @@ static void arm_smmu_domain_free(struct iommu_domain *domain)
 	if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1) {
 		struct arm_smmu_s1_cfg *cfg = &smmu_domain->s1_cfg;
 
+		/*
+		 * Prevent arm_smmu_share_asid() from rewriting CD#0 while we're
+		 * freeing it.
+		 */
+		mutex_lock(&asid_lock);
 		if (cfg->cdcfg.cdtab)
 			arm_smmu_free_cd_tables(smmu_domain);
 		arm_smmu_free_asid(&cfg->cd);
+		mutex_unlock(&asid_lock);
 	} else {
 		struct arm_smmu_s2_cfg *cfg = &smmu_domain->s2_cfg;
 		if (cfg->vmid)
@@ -2626,10 +2678,15 @@ static int arm_smmu_domain_finalise_s1(struct arm_smmu_domain *smmu_domain,
 
 	arm_smmu_init_cd(&cfg->cd);
 
+	/*
+	 * Prevent arm_smmu_share_asid() from seizing the private ASID we're
+	 * allocating here until it is written to the CD.
+	 */
+	mutex_lock(&asid_lock);
 	ret = xa_alloc(&asid_xa, &asid, &cfg->cd,
 		       XA_LIMIT(1, (1 << smmu->asid_bits) - 1), GFP_KERNEL);
 	if (ret)
-		return ret;
+		goto out_unlock;
 
 	cfg->s1cdmax = master->ssid_bits;
 
@@ -2657,12 +2714,15 @@ static int arm_smmu_domain_finalise_s1(struct arm_smmu_domain *smmu_domain,
 	if (ret)
 		goto out_free_cd_tables;
 
+	mutex_unlock(&asid_lock);
 	return 0;
 
 out_free_cd_tables:
 	arm_smmu_free_cd_tables(smmu_domain);
 out_free_asid:
 	arm_smmu_free_asid(&cfg->cd);
+out_unlock:
+	mutex_unlock(&asid_lock);
 	return ret;
 }
 
-- 
2.26.2

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  parent reply	other threads:[~2020-05-19 18:02 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-19 17:54 [PATCH v7 00/24] iommu: Shared Virtual Addressing for SMMUv3 Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 01/24] mm: Add a PASID field to mm_struct Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 02/24] iommu/ioasid: Add ioasid references Jean-Philippe Brucker
2020-05-20  2:31   ` Lu Baolu
2020-05-19 17:54 ` [PATCH v7 03/24] iommu/sva: Add PASID helpers Jean-Philippe Brucker
2020-05-20  2:41   ` Lu Baolu
2020-05-19 17:54 ` [PATCH v7 04/24] iommu: Add a page fault handler Jean-Philippe Brucker
2020-05-20  6:42   ` Lu Baolu
2020-11-11 13:57     ` Jean-Philippe Brucker
2020-11-11 23:11       ` Lu Baolu
2020-05-29  9:18   ` Xiang Zheng
2020-11-11 13:57     ` Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 05/24] arm64: mm: Add asid_gen_match() helper Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 06/24] arm64: mm: Pin down ASIDs for sharing mm with devices Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 07/24] iommu/io-pgtable-arm: Move some definitions to a header Jean-Philippe Brucker
2020-05-21 14:16   ` Will Deacon
2020-05-19 17:54 ` [PATCH v7 08/24] iommu/arm-smmu-v3: Manage ASIDs with xarray Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 09/24] arm64: cpufeature: Export symbol read_sanitised_ftr_reg() Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 10/24] iommu/arm-smmu-v3: Share process page tables Jean-Philippe Brucker
2020-05-19 17:54 ` Jean-Philippe Brucker [this message]
2020-05-19 17:54 ` [PATCH v7 12/24] iommu/arm-smmu-v3: Add support for VHE Jean-Philippe Brucker
2020-05-21 14:16   ` Will Deacon
2020-05-19 17:54 ` [PATCH v7 13/24] iommu/arm-smmu-v3: Enable broadcast TLB maintenance Jean-Philippe Brucker
2020-05-21 14:17   ` Will Deacon
2020-05-21 14:38     ` Marc Zyngier
2020-05-22 10:17       ` Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 14/24] iommu/arm-smmu-v3: Add SVA feature checking Jean-Philippe Brucker
2020-05-21 14:17   ` Will Deacon
2020-05-19 17:54 ` [PATCH v7 15/24] iommu/arm-smmu-v3: Add SVA device feature Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 16/24] iommu/arm-smmu-v3: Implement iommu_sva_bind/unbind() Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 17/24] iommu/arm-smmu-v3: Hook up ATC invalidation to mm ops Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 18/24] iommu/arm-smmu-v3: Add support for Hardware Translation Table Update Jean-Philippe Brucker
2020-05-21 11:12   ` Will Deacon
2020-05-27  3:00   ` Xiang Zheng
2020-05-27  8:41     ` Jean-Philippe Brucker
2020-08-28  9:28   ` Zenghui Yu
2020-09-16 14:11     ` Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 19/24] iommu/arm-smmu-v3: Maintain a SID->device structure Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 20/24] dt-bindings: document stall property for IOMMU masters Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 21/24] iommu/arm-smmu-v3: Add stall support for platform devices Jean-Philippe Brucker
2020-06-01 12:42   ` Shameerali Kolothum Thodi
2020-06-02  9:38     ` Jean-Philippe Brucker
2020-06-02 10:31       ` Shameerali Kolothum Thodi
2020-06-02 11:46         ` Jean-Philippe Brucker
2020-06-02 12:12           ` Shameerali Kolothum Thodi
2020-06-03  7:38             ` Jean-Philippe Brucker
2020-05-19 17:55 ` [PATCH v7 22/24] PCI/ATS: Add PRI stubs Jean-Philippe Brucker
2020-05-19 17:55 ` [PATCH v7 23/24] PCI/ATS: Export PRI functions Jean-Philippe Brucker
2020-05-19 17:55 ` [PATCH v7 24/24] iommu/arm-smmu-v3: Add support for PRI Jean-Philippe Brucker
2020-05-21 10:35 ` [PATCH v7 00/24] iommu: Shared Virtual Addressing for SMMUv3 Will Deacon
2020-05-21 14:17   ` Will Deacon

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