[RFC PATCH v1 5/8] iommufd: Prepare software MSI maps for address lists

[Andrew Jones]

Teach iommufd_sw_msi_get_map() to match an ordered physical address list
against an existing contiguous IOVA range. Mark the first map with the
range size so an identical list can reuse the allocation.

Teach iommufd_sw_msi_alloc_map() to reserve identifiers and offsets for
the complete list and build its maps on a temporary list. Keep the
existing scalar installation behavior and only publish newly allocated
maps after installation succeeds.

Signed-off-by: Andrew Jones <andrew.jones@xxxxxxxxxxxxxxxx>
---
 drivers/iommu/iommufd/driver.c          | 161 ++++++++++++++++++------
 drivers/iommu/iommufd/iommufd_private.h |   1 +
 2 files changed, 123 insertions(+), 39 deletions(-)

diff --git a/drivers/iommu/iommufd/driver.c b/drivers/iommu/iommufd/driver.c
index 8bb47a81fed1..6a0527f4b058 100644
--- a/drivers/iommu/iommufd/driver.c
+++ b/drivers/iommu/iommufd/driver.c
@@ -179,35 +179,91 @@ EXPORT_SYMBOL_NS_GPL(iommufd_viommu_report_event, "IOMMUFD");
 
 #ifdef CONFIG_IRQ_MSI_IOMMU
 /*
- * Get a iommufd_sw_msi_map for the msi physical address requested by the irq
+ * Get an iommufd_sw_msi_map for the msi physical addresses requested by the irq
  * layer. The mapping to IOVA is global to the iommufd file descriptor, every
  * domain that is attached to a device using the same MSI parameters will use
- * the same IOVA.
+ * the same contiguous IOVA range.
  */
 static struct iommufd_sw_msi_map *
-iommufd_sw_msi_get_map(struct iommufd_ctx *ictx, phys_addr_t msi_addr,
-		       const struct iommufd_sw_msi_range *sw_msi_range)
+iommufd_sw_msi_get_map(struct iommufd_ctx *ictx, const phys_addr_t *phys_addrs,
+		       unsigned int nr_addrs, const struct iommufd_sw_msi_range *sw_msi_range)
 {
-	struct iommufd_sw_msi_map *cur;
+	struct iommufd_sw_msi_map *cur, *msi_map;
+	unsigned int nr_found;
 
 	lockdep_assert_held(&ictx->sw_msi_lock);
 
-	list_for_each_entry(cur, &ictx->sw_msi_list, sw_msi_item) {
-		if (cur->sw_msi_start != sw_msi_range->start ||
-		    cur->pgoff >= sw_msi_range->length / PAGE_SIZE)
+	list_for_each_entry(msi_map, &ictx->sw_msi_list, sw_msi_item) {
+		if (msi_map->sw_msi_start != sw_msi_range->start ||
+		    msi_map->msi_addr != phys_addrs[0])
+			continue;
+		if (msi_map->range_size != nr_addrs * PAGE_SIZE)
 			continue;
-		if (cur->msi_addr == msi_addr)
-			return cur;
+		if (msi_map->pgoff > sw_msi_range->length / PAGE_SIZE ||
+		    nr_addrs > sw_msi_range->length / PAGE_SIZE - msi_map->pgoff)
+			continue;
+
+		nr_found = 0;
+		list_for_each_entry(cur, &ictx->sw_msi_list, sw_msi_item) {
+			unsigned int index;
+
+			if (cur->sw_msi_start != sw_msi_range->start ||
+			    cur->pgoff < msi_map->pgoff)
+				continue;
+			index = cur->pgoff - msi_map->pgoff;
+			if (index >= nr_addrs)
+				continue;
+			if (cur->msi_addr != phys_addrs[index])
+				break;
+			nr_found++;
+		}
+		if (nr_found == nr_addrs)
+			return msi_map;
 	}
 	return NULL;
 }
 
+static int iommufd_sw_msi_check_alloc(struct iommufd_ctx *ictx,
+				      const struct iommufd_sw_msi_range *sw_msi_range,
+				      unsigned int first_pgoff, unsigned int nr_addrs,
+				      size_t *range_size)
+{
+	unsigned long max_iova_pgoff;
+	unsigned int last_pgoff;
+	unsigned int last_id;
+	size_t range_pages;
+
+	if (!nr_addrs)
+		return -EINVAL;
+	if (sw_msi_range->start > ULONG_MAX)
+		return -EOVERFLOW;
+
+	range_pages = sw_msi_range->length / PAGE_SIZE;
+	max_iova_pgoff = (ULONG_MAX - sw_msi_range->start) / PAGE_SIZE;
+
+	if (check_add_overflow(ictx->sw_msi_id, nr_addrs - 1, &last_id) ||
+	    last_id > IOMMUFD_SW_MSI_MAX_ID ||
+	    check_add_overflow(first_pgoff, nr_addrs - 1, &last_pgoff) ||
+	    last_pgoff > max_iova_pgoff ||
+	    check_mul_overflow((size_t)nr_addrs, PAGE_SIZE, range_size))
+		return -EOVERFLOW;
+
+	if (last_pgoff >= range_pages)
+		return -ENOSPC;
+
+	return 0;
+}
+
 static struct iommufd_sw_msi_map *
-iommufd_sw_msi_alloc_map(struct iommufd_ctx *ictx, phys_addr_t msi_addr,
-			 const struct iommufd_sw_msi_range *sw_msi_range)
+iommufd_sw_msi_alloc_map(struct iommufd_ctx *ictx, const phys_addr_t *phys_addrs,
+			 unsigned int nr_addrs, const struct iommufd_sw_msi_range *sw_msi_range,
+			 struct list_head *new_msi_maps)
 {
-	struct iommufd_sw_msi_map *cur;
-	unsigned int max_pgoff = 0;
+	struct iommufd_sw_msi_map *cur, *first_map = NULL;
+	unsigned int next_pgoff = 0;
+	unsigned int i;
+	size_t size;
+	int rc;
 
 	lockdep_assert_held(&ictx->sw_msi_lock);
 
@@ -216,25 +272,38 @@ iommufd_sw_msi_alloc_map(struct iommufd_ctx *ictx, phys_addr_t msi_addr,
 			continue;
 		if (cur->pgoff == UINT_MAX)
 			return ERR_PTR(-EOVERFLOW);
-		max_pgoff = max(max_pgoff, cur->pgoff + 1);
+		next_pgoff = max(next_pgoff, cur->pgoff + 1);
 	}
 
-	if (ictx->sw_msi_id > IOMMUFD_SW_MSI_MAX_ID ||
-	    max_pgoff > (ULONG_MAX - sw_msi_range->start) / PAGE_SIZE)
-		return ERR_PTR(-EOVERFLOW);
-	if (max_pgoff >= sw_msi_range->length / PAGE_SIZE)
-		return ERR_PTR(-ENOSPC);
-
-	cur = kzalloc_obj(*cur);
-	if (!cur)
-		return ERR_PTR(-ENOMEM);
-
-	cur->sw_msi_start = sw_msi_range->start;
-	cur->msi_addr = msi_addr;
-	cur->pgoff = max_pgoff;
-	cur->id = ictx->sw_msi_id++;
-	list_add_tail(&cur->sw_msi_item, &ictx->sw_msi_list);
-	return cur;
+	rc = iommufd_sw_msi_check_alloc(ictx, sw_msi_range, next_pgoff, nr_addrs, &size);
+	if (rc)
+		return ERR_PTR(rc);
+
+	for (i = 0; i < nr_addrs; i++) {
+		cur = kzalloc_obj(*cur);
+		if (!cur)
+			goto err_free;
+
+		cur->sw_msi_start = sw_msi_range->start;
+		cur->msi_addr = phys_addrs[i];
+		cur->pgoff = next_pgoff + i;
+		cur->id = ictx->sw_msi_id + i;
+		if (!i) {
+			cur->range_size = size;
+			first_map = cur;
+		}
+		list_add_tail(&cur->sw_msi_item, new_msi_maps);
+	}
+
+	return first_map;
+
+err_free:
+	while (!list_empty(new_msi_maps)) {
+		cur = list_first_entry(new_msi_maps, typeof(*cur), sw_msi_item);
+		list_del(&cur->sw_msi_item);
+		kfree(cur);
+	}
+	return ERR_PTR(-ENOMEM);
 }
 
 int iommufd_sw_msi_install(struct iommufd_ctx *ictx,
@@ -280,7 +349,9 @@ int iommufd_sw_msi(struct iommu_domain *domain, struct msi_desc *desc,
 	struct iommufd_attach_handle *handle;
 	struct iommufd_sw_msi_map *msi_map;
 	struct iommufd_ctx *ictx;
+	LIST_HEAD(new_msi_maps);
 	unsigned long iova;
+	phys_addr_t phys_addr;
 	int rc;
 
 	/*
@@ -308,29 +379,41 @@ int iommufd_sw_msi(struct iommu_domain *domain, struct msi_desc *desc,
 	 * assume the caller has checked that it is contained with a MMIO region
 	 * that is secure to map at PAGE_SIZE.
 	 */
-	msi_map = iommufd_sw_msi_get_map(handle->idev->ictx,
-					 msi_addr & PAGE_MASK,
-					 &handle->idev->igroup->sw_msi_range);
+	phys_addr = msi_addr & PAGE_MASK;
+	msi_map = iommufd_sw_msi_get_map(ictx, &phys_addr, 1, &handle->idev->igroup->sw_msi_range);
 	if (!msi_map)
-		msi_map = iommufd_sw_msi_alloc_map(handle->idev->ictx,
-						   msi_addr & PAGE_MASK,
-						   &handle->idev->igroup->sw_msi_range);
+		msi_map = iommufd_sw_msi_alloc_map(ictx, &phys_addr, 1,
+						   &handle->idev->igroup->sw_msi_range,
+						   &new_msi_maps);
 	if (IS_ERR(msi_map))
 		return PTR_ERR(msi_map);
 
 	rc = iommufd_sw_msi_maps_ensure(&handle->idev->igroup->required_sw_msi,
 					msi_map->id);
 	if (rc)
-		return rc;
+		goto err_free;
 
 	rc = iommufd_sw_msi_install(ictx, hwpt_paging, msi_map);
 	if (rc)
-		return rc;
+		goto err_free;
 	__set_bit(msi_map->id, handle->idev->igroup->required_sw_msi.bitmap);
 
+	if (!list_empty(&new_msi_maps)) {
+		list_splice_tail_init(&new_msi_maps, &ictx->sw_msi_list);
+		ictx->sw_msi_id++;
+	}
+
 	iova = msi_map->sw_msi_start + msi_map->pgoff * PAGE_SIZE;
 	msi_desc_set_iommu_msi_iova(desc, iova, PAGE_SHIFT);
 	return 0;
+
+err_free:
+	while (!list_empty(&new_msi_maps)) {
+		msi_map = list_first_entry(&new_msi_maps, typeof(*msi_map), sw_msi_item);
+		list_del(&msi_map->sw_msi_item);
+		kfree(msi_map);
+	}
+	return rc;
 }
 EXPORT_SYMBOL_NS_GPL(iommufd_sw_msi, "IOMMUFD");
 #endif
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 4e2d32809695..797965557281 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -33,6 +33,7 @@ struct iommufd_sw_msi_map {
 	phys_addr_t msi_addr;
 	unsigned int pgoff;
 	unsigned int id;
+	size_t range_size; /* IOVA range size, or 0 if not the first map */
 };
 
 /* Bitmap of struct iommufd_sw_msi_map::id; starts empty, grows on demand. */
-- 
2.43.0