[PATCH v2 01/14] iommufd: Convert struct iommufd_sw_msi_maps to a growable bitmap

struct iommufd_sw_msi_maps currently uses a fixed 64-bit bitmap,
capping the number of distinct SW MSI mappings a context or hwpt can
track. An upcoming caller needs one mapping per possible CPU.

Convert the fixed bitmap to a pointer plus size that grows on demand
via iommufd_sw_msi_maps_ensure(). Add iommufd_sw_msi_maps_test_bit()
alongside it: unlike the __set_bit() call sites, which always follow
their own successful iommufd_sw_msi_maps_ensure() call on the same id,
iommufd_group_setup_msi() tests an id from the fd-global sw_msi_list
against a specific group's required_sw_msi map, which may not have
been grown to cover that id yet.

Signed-off-by: Andrew Jones <[email protected]>
---
 drivers/iommu/iommufd/device.c          |  3 +-
 drivers/iommu/iommufd/driver.c          | 38 ++++++++++++++++---------
 drivers/iommu/iommufd/hw_pagetable.c    |  1 +
 drivers/iommu/iommufd/iommufd_private.h | 38 +++++++++++++++++++++++--
 4 files changed, 64 insertions(+), 16 deletions(-)

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index 170a7005f0bc..402251c7b887 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -34,6 +34,7 @@ static void iommufd_group_release(struct kref *kref)
 		   NULL, GFP_KERNEL);
 	iommu_group_put(igroup->group);
 	mutex_destroy(&igroup->lock);
+	kfree(igroup->required_sw_msi.bitmap);
 	kfree(igroup);
 }
 
@@ -384,7 +385,7 @@ static int iommufd_group_setup_msi(struct iommufd_group *igroup,
 		int rc;
 
 		if (cur->sw_msi_start != igroup->sw_msi_start ||
-		    !test_bit(cur->id, igroup->required_sw_msi.bitmap))
+		    !iommufd_sw_msi_maps_test_bit(&igroup->required_sw_msi, cur->id))
 			continue;
 
 		rc = iommufd_sw_msi_install(ictx, hwpt_paging, cur);
diff --git a/drivers/iommu/iommufd/driver.c b/drivers/iommu/iommufd/driver.c
index 3b8067976eac..3cd617dfc351 100644
--- a/drivers/iommu/iommufd/driver.c
+++ b/drivers/iommu/iommufd/driver.c
@@ -196,13 +196,15 @@ iommufd_sw_msi_get_map(struct iommufd_ctx *ictx, phys_addr_t msi_addr,
 	list_for_each_entry(cur, &ictx->sw_msi_list, sw_msi_item) {
 		if (cur->sw_msi_start != sw_msi_start)
 			continue;
+		if (cur->pgoff == UINT_MAX)
+			return ERR_PTR(-EOVERFLOW);
 		max_pgoff = max(max_pgoff, cur->pgoff + 1);
 		if (cur->msi_addr == msi_addr)
 			return cur;
 	}
 
-	if (ictx->sw_msi_id >=
-	    BITS_PER_BYTE * sizeof_field(struct iommufd_sw_msi_maps, bitmap))
+	if (ictx->sw_msi_id == UINT_MAX ||
+	    max_pgoff > (ULONG_MAX - sw_msi_start) / PAGE_SIZE)
 		return ERR_PTR(-EOVERFLOW);
 
 	cur = kzalloc_obj(*cur);
@@ -222,21 +224,26 @@ int iommufd_sw_msi_install(struct iommufd_ctx *ictx,
 			   struct iommufd_sw_msi_map *msi_map)
 {
 	unsigned long iova;
+	int rc;
 
 	lockdep_assert_held(&ictx->sw_msi_lock);
 
+	if (iommufd_sw_msi_maps_test_bit(&hwpt_paging->present_sw_msi,
+					 msi_map->id))
+		return 0;
+
 	iova = msi_map->sw_msi_start + msi_map->pgoff * PAGE_SIZE;
-	if (!test_bit(msi_map->id, hwpt_paging->present_sw_msi.bitmap)) {
-		int rc;
-
-		rc = iommu_map(hwpt_paging->common.domain, iova,
-			       msi_map->msi_addr, PAGE_SIZE,
-			       IOMMU_WRITE | IOMMU_READ | IOMMU_MMIO,
-			       GFP_KERNEL_ACCOUNT);
-		if (rc)
-			return rc;
-		__set_bit(msi_map->id, hwpt_paging->present_sw_msi.bitmap);
-	}
+	rc = iommufd_sw_msi_maps_ensure(&hwpt_paging->present_sw_msi, msi_map->id);
+	if (rc)
+		return rc;
+
+	rc = iommu_map(hwpt_paging->common.domain, iova,
+		       msi_map->msi_addr, PAGE_SIZE,
+		       IOMMU_WRITE | IOMMU_READ | IOMMU_MMIO,
+		       GFP_KERNEL_ACCOUNT);
+	if (rc)
+		return rc;
+	__set_bit(msi_map->id, hwpt_paging->present_sw_msi.bitmap);
 	return 0;
 }
 EXPORT_SYMBOL_NS_GPL(iommufd_sw_msi_install, "IOMMUFD_INTERNAL");
@@ -290,6 +297,11 @@ int iommufd_sw_msi(struct iommu_domain *domain, struct msi_desc *desc,
 	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;
+
 	rc = iommufd_sw_msi_install(ictx, hwpt_paging, msi_map);
 	if (rc)
 		return rc;
diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c
index 623cc608ca0c..54873de43eb0 100644
--- a/drivers/iommu/iommufd/hw_pagetable.c
+++ b/drivers/iommu/iommufd/hw_pagetable.c
@@ -32,6 +32,7 @@ void iommufd_hwpt_paging_destroy(struct iommufd_object *obj)
 	}
 
 	__iommufd_hwpt_destroy(&hwpt_paging->common);
+	kfree(hwpt_paging->present_sw_msi.bitmap);
 	refcount_dec(&hwpt_paging->ioas->obj.users);
 }
 
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 43fbc5bed8de..44d6dc94fb6b 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -29,11 +29,45 @@ struct iommufd_sw_msi_map {
 	unsigned int id;
 };
 
-/* Bitmap of struct iommufd_sw_msi_map::id */
+/* Bitmap of struct iommufd_sw_msi_map::id; starts empty, grows on demand. */
 struct iommufd_sw_msi_maps {
-	DECLARE_BITMAP(bitmap, 64);
+	unsigned long *bitmap;
+	unsigned int nbits;
 };
 
+/* Grow bitmap to accommodate id. Must be called under ictx->sw_msi_lock. */
+static inline int iommufd_sw_msi_maps_ensure(struct iommufd_sw_msi_maps *maps,
+					     unsigned int id)
+{
+	unsigned long *new_bitmap;
+	unsigned int new_nbits;
+
+	if (id < maps->nbits)
+		return 0;
+
+	new_nbits = ALIGN(max(maps->nbits ? maps->nbits * 2 : 64U, id + 1),
+			  BITS_PER_LONG);
+	if (new_nbits <= id)
+		return -EOVERFLOW;
+	new_bitmap = krealloc(maps->bitmap,
+			      BITS_TO_LONGS(new_nbits) * sizeof(unsigned long),
+			      GFP_KERNEL_ACCOUNT);
+	if (!new_bitmap)
+		return -ENOMEM;
+	bitmap_clear(new_bitmap, maps->nbits, new_nbits - maps->nbits);
+	maps->bitmap = new_bitmap;
+	maps->nbits = new_nbits;
+	return 0;
+}
+
+static inline bool iommufd_sw_msi_maps_test_bit(const struct iommufd_sw_msi_maps *maps,
+						unsigned int id)
+{
+	if (id >= maps->nbits)
+		return false;
+	return test_bit(id, maps->bitmap);
+}
+
 #ifdef CONFIG_IRQ_MSI_IOMMU
 int iommufd_sw_msi_install(struct iommufd_ctx *ictx,
 			   struct iommufd_hwpt_paging *hwpt_paging,
-- 
2.43.0