vfio: selftests: Keep track of DMA regions mapped into the device

Keep track of the list of DMA regions that are mapped into the device
using a linked list and a new struct vfio_dma_region and use that to add
{__,}to_iova() for converting host virtual addresses into IOVAs.

This will be used in a subsequent commit to map multiple DMA regions
into a device that are then used by drivers.

Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: David Matlack <dmatlack@google.com>
Link: https://lore.kernel.org/r/20250822212518.4156428-10-dmatlack@google.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

tools/testing/selftests/vfio/lib/include/vfio_util.h

@@ -51,6 +51,17 @@ struct vfio_pci_bar {
 	void *vaddr;
 };
 
+typedef u64 iova_t;
+
+#define INVALID_IOVA UINT64_MAX
+
+struct vfio_dma_region {
+	struct list_head link;
+	void *vaddr;
+	iova_t iova;
+	u64 size;
+};
+
 struct vfio_pci_device {
 	int fd;
 	int group_fd;
@@ -63,6 +74,8 @@ struct vfio_pci_device {
 	struct vfio_irq_info msi_info;
 	struct vfio_irq_info msix_info;
 
+	struct list_head dma_regions;
+
 	/* eventfds for MSI and MSI-x interrupts */
 	int msi_eventfds[PCI_MSIX_FLAGS_QSIZE + 1];
 };
@@ -85,9 +98,10 @@ struct vfio_pci_device *vfio_pci_device_init(const char *bdf, int iommu_type);
 void vfio_pci_device_cleanup(struct vfio_pci_device *device);
 void vfio_pci_device_reset(struct vfio_pci_device *device);
 
-void vfio_pci_dma_map(struct vfio_pci_device *device, u64 iova, u64 size,
-		      void *vaddr);
-void vfio_pci_dma_unmap(struct vfio_pci_device *device, u64 iova, u64 size);
+void vfio_pci_dma_map(struct vfio_pci_device *device,
+		      struct vfio_dma_region *region);
+void vfio_pci_dma_unmap(struct vfio_pci_device *device,
+			struct vfio_dma_region *region);
 
 void vfio_pci_config_access(struct vfio_pci_device *device, bool write,
 			    size_t config, size_t size, void *data);
@@ -138,4 +152,7 @@ static inline void vfio_pci_msix_disable(struct vfio_pci_device *device)
 	vfio_pci_irq_disable(device, VFIO_PCI_MSIX_IRQ_INDEX);
 }
 
+iova_t __to_iova(struct vfio_pci_device *device, void *vaddr);
+iova_t to_iova(struct vfio_pci_device *device, void *vaddr);
+
 #endif /* SELFTESTS_VFIO_LIB_INCLUDE_VFIO_UTIL_H */

tools/testing/selftests/vfio/lib/vfio_pci_device.c

@@ -26,6 +26,33 @@
 	VFIO_ASSERT_EQ(__ret, 0, "ioctl(%s, %s, %s) returned %d\n", #_fd, #_op, #_arg, __ret); \
 } while (0)
 
+iova_t __to_iova(struct vfio_pci_device *device, void *vaddr)
+{
+	struct vfio_dma_region *region;
+
+	list_for_each_entry(region, &device->dma_regions, link) {
+		if (vaddr < region->vaddr)
+			continue;
+
+		if (vaddr >= region->vaddr + region->size)
+			continue;
+
+		return region->iova + (vaddr - region->vaddr);
+	}
+
+	return INVALID_IOVA;
+}
+
+iova_t to_iova(struct vfio_pci_device *device, void *vaddr)
+{
+	iova_t iova;
+
+	iova = __to_iova(device, vaddr);
+	VFIO_ASSERT_NE(iova, INVALID_IOVA, "%p is not mapped into device.\n", vaddr);
+
+	return iova;
+}
+
 static void vfio_pci_irq_set(struct vfio_pci_device *device,
 			     u32 index, u32 vector, u32 count, int *fds)
 {
@@ -112,28 +139,34 @@ static void vfio_pci_irq_get(struct vfio_pci_device *device, u32 index,
 	ioctl_assert(device->fd, VFIO_DEVICE_GET_IRQ_INFO, irq_info);
 }
 
-void vfio_pci_dma_map(struct vfio_pci_device *device, u64 iova, u64 size, void *vaddr)
+void vfio_pci_dma_map(struct vfio_pci_device *device,
+		      struct vfio_dma_region *region)
 {
 	struct vfio_iommu_type1_dma_map map = {
 		.argsz = sizeof(map),
 		.flags = VFIO_DMA_MAP_FLAG_READ | VFIO_DMA_MAP_FLAG_WRITE,
-		.vaddr = (u64)vaddr,
-		.iova = iova,
-		.size = size,
+		.vaddr = (u64)region->vaddr,
+		.iova = region->iova,
+		.size = region->size,
 	};
 
 	ioctl_assert(device->container_fd, VFIO_IOMMU_MAP_DMA, &map);
+
+	list_add(&region->link, &device->dma_regions);
 }
 
-void vfio_pci_dma_unmap(struct vfio_pci_device *device, u64 iova, u64 size)
+void vfio_pci_dma_unmap(struct vfio_pci_device *device,
+			struct vfio_dma_region *region)
 {
 	struct vfio_iommu_type1_dma_unmap unmap = {
 		.argsz = sizeof(unmap),
-		.iova = iova,
-		.size = size,
+		.iova = region->iova,
+		.size = region->size,
 	};
 
 	ioctl_assert(device->container_fd, VFIO_IOMMU_UNMAP_DMA, &unmap);
+
+	list_del(&region->link);
 }
 
 static void vfio_pci_region_get(struct vfio_pci_device *device, int index,
@@ -260,6 +293,8 @@ static void vfio_pci_iommu_setup(struct vfio_pci_device *device, unsigned long i
 {
 	int ret;
 
+	INIT_LIST_HEAD(&device->dma_regions);
+
 	ret = ioctl(device->container_fd, VFIO_CHECK_EXTENSION, iommu_type);
 	VFIO_ASSERT_GT(ret, 0, "VFIO IOMMU type %lu not supported\n", iommu_type);
 

tools/testing/selftests/vfio/vfio_dma_mapping_test.c

@@ -128,30 +128,32 @@ TEST_F(vfio_dma_mapping_test, dma_map_unmap)
 {
 	const u64 size = variant->size ?: getpagesize();
 	const int flags = variant->mmap_flags;
+	struct vfio_dma_region region;
 	struct iommu_mapping mapping;
-	void *mem;
-	u64 iova;
 	int rc;
 
-	mem = mmap(NULL, size, PROT_READ | PROT_WRITE, flags, -1, 0);
+	region.vaddr = mmap(NULL, size, PROT_READ | PROT_WRITE, flags, -1, 0);
 
 	/* Skip the test if there aren't enough HugeTLB pages available. */
-	if (flags & MAP_HUGETLB && mem == MAP_FAILED)
+	if (flags & MAP_HUGETLB && region.vaddr == MAP_FAILED)
 		SKIP(return, "mmap() failed: %s (%d)\n", strerror(errno), errno);
 	else
-		ASSERT_NE(mem, MAP_FAILED);
+		ASSERT_NE(region.vaddr, MAP_FAILED);
 
-	iova = (u64)mem;
+	region.iova = (u64)region.vaddr;
+	region.size = size;
 
-	vfio_pci_dma_map(self->device, iova, size, mem);
-	printf("Mapped HVA %p (size 0x%lx) at IOVA 0x%lx\n", mem, size, iova);
+	vfio_pci_dma_map(self->device, &region);
+	printf("Mapped HVA %p (size 0x%lx) at IOVA 0x%lx\n", region.vaddr, size, region.iova);
 
-	rc = iommu_mapping_get(device_bdf, iova, &mapping);
+	ASSERT_EQ(region.iova, to_iova(self->device, region.vaddr));
+
+	rc = iommu_mapping_get(device_bdf, region.iova, &mapping);
 	if (rc == -EOPNOTSUPP)
 		goto unmap;
 
 	ASSERT_EQ(0, rc);
-	printf("Found IOMMU mappings for IOVA 0x%lx:\n", iova);
+	printf("Found IOMMU mappings for IOVA 0x%lx:\n", region.iova);
 	printf("PGD: 0x%016lx\n", mapping.pgd);
 	printf("P4D: 0x%016lx\n", mapping.p4d);
 	printf("PUD: 0x%016lx\n", mapping.pud);
@@ -176,11 +178,12 @@ TEST_F(vfio_dma_mapping_test, dma_map_unmap)
 	}
 
 unmap:
-	vfio_pci_dma_unmap(self->device, iova, size);
-	printf("Unmapped IOVA 0x%lx\n", iova);
-	ASSERT_NE(0, iommu_mapping_get(device_bdf, iova, &mapping));
+	vfio_pci_dma_unmap(self->device, &region);
+	printf("Unmapped IOVA 0x%lx\n", region.iova);
+	ASSERT_EQ(INVALID_IOVA, __to_iova(self->device, region.vaddr));
+	ASSERT_NE(0, iommu_mapping_get(device_bdf, region.iova, &mapping));
 
-	ASSERT_TRUE(!munmap(mem, size));
+	ASSERT_TRUE(!munmap(region.vaddr, size));
 }
 
 int main(int argc, char *argv[])