Re: [PATCH v3 09/11] iommu: Make iommu_queue_iopf() more generic

Baolu Lu <baolu.lu@xxxxxxxxxxxxxxx> · Tue, 22 Aug 2023 16:47:55 +0800

On 2023/8/22 1:11, Jason Gunthorpe wrote:
On Fri, Aug 18, 2023 at 07:40:45AM +0800, Lu Baolu wrote:
This completely separates the IO page fault handling framework from the
SVA implementation. Previously, the SVA implementation was tightly coupled
with the IO page fault handling framework. This makes SVA a "customer" of
the IO page fault handling framework by converting domain's page fault
handler to handle a group of faults and calling it directly from
iommu_queue_iopf().

Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
---
  include/linux/iommu.h      |  5 +++--
  drivers/iommu/iommu-sva.h  |  8 --------
  drivers/iommu/io-pgfault.c | 16 +++++++++++++---
  drivers/iommu/iommu-sva.c  | 14 ++++----------
  drivers/iommu/iommu.c      |  4 ++--
  5 files changed, 22 insertions(+), 25 deletions(-)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index ff292eea9d31..cf1cb0bb46af 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -41,6 +41,7 @@ struct iommu_sva;
  struct iommu_fault_event;
  struct iommu_dma_cookie;
  struct iopf_queue;
+struct iopf_group;
  
  #define IOMMU_FAULT_PERM_READ	(1 << 0) /* read */
  #define IOMMU_FAULT_PERM_WRITE	(1 << 1) /* write */
@@ -175,8 +176,7 @@ struct iommu_domain {
  	unsigned long pgsize_bitmap;	/* Bitmap of page sizes in use */
  	struct iommu_domain_geometry geometry;
  	struct iommu_dma_cookie *iova_cookie;
-	enum iommu_page_response_code (*iopf_handler)(struct iommu_fault *fault,
-						      void *data);
+	int (*iopf_handler)(struct iopf_group *group);
  	void *fault_data;
  	union {
  		struct {
@@ -526,6 +526,7 @@ struct iopf_group {
  	struct list_head		faults;
  	struct work_struct		work;
  	struct device			*dev;
+	void				*data;
  };
  
  int iommu_device_register(struct iommu_device *iommu,
diff --git a/drivers/iommu/iommu-sva.h b/drivers/iommu/iommu-sva.h
index 510a7df23fba..cf41e88fac17 100644
--- a/drivers/iommu/iommu-sva.h
+++ b/drivers/iommu/iommu-sva.h
@@ -22,8 +22,6 @@ int iopf_queue_flush_dev(struct device *dev);
  struct iopf_queue *iopf_queue_alloc(const char *name);
  void iopf_queue_free(struct iopf_queue *queue);
  int iopf_queue_discard_partial(struct iopf_queue *queue);
-enum iommu_page_response_code
-iommu_sva_handle_iopf(struct iommu_fault *fault, void *data);
  void iopf_free_group(struct iopf_group *group);
  int iopf_queue_work(struct iopf_group *group, work_func_t func);
  int iommu_sva_handle_iopf_group(struct iopf_group *group);
@@ -65,12 +63,6 @@ static inline int iopf_queue_discard_partial(struct iopf_queue *queue)
  	return -ENODEV;
  }
  
-static inline enum iommu_page_response_code
-iommu_sva_handle_iopf(struct iommu_fault *fault, void *data)
-{
-	return IOMMU_PAGE_RESP_INVALID;
-}
-
  static inline void iopf_free_group(struct iopf_group *group)
  {
  }
diff --git a/drivers/iommu/io-pgfault.c b/drivers/iommu/io-pgfault.c
index 00c2e447b740..a61c2aabd1b8 100644
--- a/drivers/iommu/io-pgfault.c
+++ b/drivers/iommu/io-pgfault.c
@@ -11,8 +11,6 @@
  #include <linux/slab.h>
  #include <linux/workqueue.h>
  
-#include "iommu-sva.h"
-
  /**
   * struct iopf_queue - IO Page Fault queue
   * @wq: the fault workqueue
@@ -93,6 +91,7 @@ int iommu_queue_iopf(struct iommu_fault *fault, struct device *dev)
  {
  	int ret;
  	struct iopf_group *group;
+	struct iommu_domain *domain;
  	struct iopf_fault *iopf, *next;
  	struct iommu_fault_param *iopf_param;
  	struct dev_iommu *param = dev->iommu;
@@ -124,6 +123,16 @@ int iommu_queue_iopf(struct iommu_fault *fault, struct device *dev)
  		return 0;
  	}
  
+	if (fault->prm.flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID)
+		domain = iommu_get_domain_for_dev_pasid(dev, fault->prm.pasid, 0);
+	else
+		domain = iommu_get_domain_for_dev(dev);
+
+	if (!domain || !domain->iopf_handler) {
+		ret = -ENODEV;
+		goto cleanup_partial;
+	}
+
  	group = kzalloc(sizeof(*group), GFP_KERNEL);
  	if (!group) {
  		/*
@@ -137,6 +146,7 @@ int iommu_queue_iopf(struct iommu_fault *fault, struct device *dev)
  
  	group->dev = dev;
  	group->last_fault.fault = *fault;
+	group->data = domain->fault_data;
  	INIT_LIST_HEAD(&group->faults);
  	list_add(&group->last_fault.list, &group->faults);
  
@@ -147,7 +157,7 @@ int iommu_queue_iopf(struct iommu_fault *fault, struct device *dev)
  			list_move(&iopf->list, &group->faults);
  	}
  
-	ret = iommu_sva_handle_iopf_group(group);
+	ret = domain->iopf_handler(group);
  	if (ret)
  		iopf_free_group(group);
  
diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
index df8734b6ec00..2811f34947ab 100644
--- a/drivers/iommu/iommu-sva.c
+++ b/drivers/iommu/iommu-sva.c
@@ -148,13 +148,14 @@ EXPORT_SYMBOL_GPL(iommu_sva_get_pasid);
  /*
   * I/O page fault handler for SVA
   */
-enum iommu_page_response_code
+static enum iommu_page_response_code
  iommu_sva_handle_iopf(struct iommu_fault *fault, void *data)
  {
  	vm_fault_t ret;
  	struct vm_area_struct *vma;
-	struct mm_struct *mm = data;
  	unsigned int access_flags = 0;
+	struct iommu_domain *domain = data;
+	struct mm_struct *mm = domain->mm;
  	unsigned int fault_flags = FAULT_FLAG_REMOTE;
  	struct iommu_fault_page_request *prm = &fault->prm;
  	enum iommu_page_response_code status = IOMMU_PAGE_RESP_INVALID;
@@ -231,23 +232,16 @@ static void iommu_sva_iopf_handler(struct work_struct *work)
  {
  	struct iopf_fault *iopf;
  	struct iopf_group *group;
-	struct iommu_domain *domain;
  	enum iommu_page_response_code status = IOMMU_PAGE_RESP_SUCCESS;
  
  	group = container_of(work, struct iopf_group, work);
-	domain = iommu_get_domain_for_dev_pasid(group->dev,
-				group->last_fault.fault.prm.pasid, 0);
-	if (!domain || !domain->iopf_handler)
-		status = IOMMU_PAGE_RESP_INVALID;
-
  	list_for_each_entry(iopf, &group->faults, list) {
  		/*
  		 * For the moment, errors are sticky: don't handle subsequent
  		 * faults in the group if there is an error.
  		 */
  		if (status == IOMMU_PAGE_RESP_SUCCESS)
-			status = domain->iopf_handler(&iopf->fault,
-						      domain->fault_data);
+			status = iommu_sva_handle_iopf(&iopf->fault, group->data);
  	}
  
  	iommu_sva_complete_iopf(group->dev, &group->last_fault, status);
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index b280b9f4d8b4..9b622088c741 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -3395,8 +3395,8 @@ struct iommu_domain *iommu_sva_domain_alloc(struct device *dev,
  	domain->type = IOMMU_DOMAIN_SVA;
  	mmgrab(mm);
  	domain->mm = mm;
-	domain->iopf_handler = iommu_sva_handle_iopf;
-	domain->fault_data = mm;
+	domain->iopf_handler = iommu_sva_handle_iopf_group;
+	domain->fault_data = domain;

Why fault_data? The domain handling the fault should be passed
through naturally without relying on fault_data.

eg make

   iommu_sva_handle_iopf(struct iommu_fault *fault, void *data)

into
   iommu_sva_handle_iopf(struct iommu_fault *fault, struct iommu_domain *domain)

See your point now. I will remove "void *data" and move "domain" to
"group->domain".


And delete domain->fault_data until we have some use for it.

Perhaps we will soon have a use for it.

In the iommufd case, the iommufd iopf handler has a need to retrieve the
hwpt pointer from a domain pointer, right? With the domain->fault_data
pointing to the hwpt, the iopf handler has no need to lookup it in the
critical path.


The core code should be keeping track of the iommu_domain lifetime.

I added the debugging code in the next patch as you suggested.

Best regards,
baolu






