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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: Jean-Philippe Brucker <jean-philippe@linaro.org>,
	kevin.tian@intel.com, catalin.marinas@arm.com,
	robin.murphy@arm.com, jgg@ziepe.ca, zhangfei.gao@linaro.org,
	will@kernel.org, christian.koenig@amd.com
Subject: [PATCH v5 05/25] iommu/iopf: Handle mm faults
Date: Tue, 14 Apr 2020 19:02:33 +0200
Message-ID: <20200414170252.714402-6-jean-philippe@linaro.org> (raw)
In-Reply-To: <20200414170252.714402-1-jean-philippe@linaro.org>

When a recoverable page fault is handled by the fault workqueue, find the
associated mm and call handle_mm_fault.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
v4->v5: no need to call mmput_async() anymore, since the MMU release()
        doesn't flush the IOPF queue anymore.
---
 drivers/iommu/io-pgfault.c | 77 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 75 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/io-pgfault.c b/drivers/iommu/io-pgfault.c
index 5bba8e6a13be2..fd4244023b33f 100644
--- a/drivers/iommu/io-pgfault.c
+++ b/drivers/iommu/io-pgfault.c
@@ -7,6 +7,7 @@
 
 #include <linux/iommu.h>
 #include <linux/list.h>
+#include <linux/sched/mm.h>
 #include <linux/slab.h>
 #include <linux/workqueue.h>
 
@@ -76,8 +77,57 @@ static int iopf_complete_group(struct device *dev, struct iopf_fault *iopf,
 static enum iommu_page_response_code
 iopf_handle_single(struct iopf_fault *iopf)
 {
-	/* TODO */
-	return -ENODEV;
+	vm_fault_t ret;
+	struct mm_struct *mm;
+	struct vm_area_struct *vma;
+	unsigned int access_flags = 0;
+	unsigned int fault_flags = FAULT_FLAG_REMOTE;
+	struct iommu_fault_page_request *prm = &iopf->fault.prm;
+	enum iommu_page_response_code status = IOMMU_PAGE_RESP_INVALID;
+
+	if (!(prm->flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID))
+		return status;
+
+	mm = iommu_sva_find(prm->pasid);
+	if (IS_ERR_OR_NULL(mm))
+		return status;
+
+	down_read(&mm->mmap_sem);
+
+	vma = find_extend_vma(mm, prm->addr);
+	if (!vma)
+		/* Unmapped area */
+		goto out_put_mm;
+
+	if (prm->perm & IOMMU_FAULT_PERM_READ)
+		access_flags |= VM_READ;
+
+	if (prm->perm & IOMMU_FAULT_PERM_WRITE) {
+		access_flags |= VM_WRITE;
+		fault_flags |= FAULT_FLAG_WRITE;
+	}
+
+	if (prm->perm & IOMMU_FAULT_PERM_EXEC) {
+		access_flags |= VM_EXEC;
+		fault_flags |= FAULT_FLAG_INSTRUCTION;
+	}
+
+	if (!(prm->perm & IOMMU_FAULT_PERM_PRIV))
+		fault_flags |= FAULT_FLAG_USER;
+
+	if (access_flags & ~vma->vm_flags)
+		/* Access fault */
+		goto out_put_mm;
+
+	ret = handle_mm_fault(vma, prm->addr, fault_flags);
+	status = ret & VM_FAULT_ERROR ? IOMMU_PAGE_RESP_INVALID :
+		IOMMU_PAGE_RESP_SUCCESS;
+
+out_put_mm:
+	up_read(&mm->mmap_sem);
+	mmput(mm);
+
+	return status;
 }
 
 static void iopf_handle_group(struct work_struct *work)
@@ -112,6 +162,29 @@ static void iopf_handle_group(struct work_struct *work)
  *
  * Add a fault to the device workqueue, to be handled by mm.
  *
+ * This module doesn't handle PCI PASID Stop Marker; IOMMU drivers must discard
+ * them before reporting faults. A PASID Stop Marker (LRW = 0b100) doesn't
+ * expect a response. It may be generated when disabling a PASID (issuing a
+ * PASID stop request) by some PCI devices.
+ *
+ * The PASID stop request is issued by the device driver before unbind(). Once
+ * it completes, no page request is generated for this PASID anymore and
+ * outstanding ones have been pushed to the IOMMU (as per PCIe 4.0r1.0 - 6.20.1
+ * and 10.4.1.2 - Managing PASID TLP Prefix Usage). Some PCI devices will wait
+ * for all outstanding page requests to come back with a response before
+ * completing the PASID stop request. Others do not wait for page responses, and
+ * instead issue this Stop Marker that tells us when the PASID can be
+ * reallocated.
+ *
+ * It is safe to discard the Stop Marker because it is an optimization.
+ * a. Page requests, which are posted requests, have been flushed to the IOMMU
+ *    when the stop request completes.
+ * b. We flush all fault queues on unbind() before freeing the PASID.
+ *
+ * So even though the Stop Marker might be issued by the device *after* the stop
+ * request completes, outstanding faults will have been dealt with by the time
+ * we free the PASID.
+ *
  * Return: 0 on success and <0 on error.
  */
 int iommu_queue_iopf(struct iommu_fault *fault, void *cookie)
-- 
2.26.0

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  parent reply index

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-14 17:02 [PATCH v5 00/25] iommu: Shared Virtual Addressing and SMMUv3 support Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 01/25] mm/mmu_notifiers: pass private data down to alloc_notifier() Jean-Philippe Brucker
2020-04-14 18:09   ` Jason Gunthorpe
2020-04-14 17:02 ` [PATCH v5 02/25] iommu/sva: Manage process address spaces Jean-Philippe Brucker
2020-04-16  7:28   ` Christoph Hellwig
2020-04-16  8:54     ` Jean-Philippe Brucker
2020-04-16 12:13       ` Christoph Hellwig
2020-04-20  7:42         ` Jean-Philippe Brucker
2020-04-20  8:10           ` Christoph Hellwig
2020-04-20 11:44             ` Christian König
2020-04-20 11:55               ` Christoph Hellwig
2020-04-20 12:40                 ` Christian König
2020-04-20 15:00                   ` Felix Kuehling
2020-04-20 17:44                     ` Jacob Pan
2020-04-20 17:52                       ` Felix Kuehling
2020-04-20 13:57           ` Jason Gunthorpe
2020-04-20 17:48             ` Jacob Pan
2020-04-20 18:14               ` Fenghua Yu
2020-04-21  8:55                 ` Christoph Hellwig
2020-04-14 17:02 ` [PATCH v5 03/25] iommu: Add a page fault handler Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 04/25] iommu/sva: Search mm by PASID Jean-Philippe Brucker
2020-04-14 17:02 ` Jean-Philippe Brucker [this message]
2020-04-14 17:02 ` [PATCH v5 06/25] iommu/sva: Register page fault handler Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 07/25] arm64: mm: Add asid_gen_match() helper Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 08/25] arm64: mm: Pin down ASIDs for sharing mm with devices Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 09/25] iommu/io-pgtable-arm: Move some definitions to a header Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 10/25] iommu/arm-smmu-v3: Manage ASIDs with xarray Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 11/25] arm64: cpufeature: Export symbol read_sanitised_ftr_reg() Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 12/25] iommu/arm-smmu-v3: Share process page tables Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 13/25] iommu/arm-smmu-v3: Seize private ASID Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 14/25] iommu/arm-smmu-v3: Add support for VHE Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 15/25] iommu/arm-smmu-v3: Enable broadcast TLB maintenance Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 16/25] iommu/arm-smmu-v3: Add SVA feature checking Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 17/25] iommu/arm-smmu-v3: Implement mm operations Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 18/25] iommu/arm-smmu-v3: Hook up ATC invalidation to mm ops Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 19/25] iommu/arm-smmu-v3: Add support for Hardware Translation Table Update Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 20/25] iommu/arm-smmu-v3: Maintain a SID->device structure Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 21/25] dt-bindings: document stall property for IOMMU masters Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 22/25] iommu/arm-smmu-v3: Add stall support for platform devices Jean-Philippe Brucker
2020-04-14 17:02 ` [PATCH v5 23/25] PCI/ATS: Add PRI stubs Jean-Philippe Brucker
2020-04-14 18:03   ` Kuppuswamy, Sathyanarayanan
2020-04-14 17:02 ` [PATCH v5 24/25] PCI/ATS: Export PRI functions Jean-Philippe Brucker
2020-04-14 18:03   ` Kuppuswamy, Sathyanarayanan
2020-04-14 17:02 ` [PATCH v5 25/25] iommu/arm-smmu-v3: Add support for PRI Jean-Philippe Brucker

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