[PATCH 1/2] vfio: selftests: Add support of creating multiple iommus from iommufd

[PATCH 1/2] vfio: selftests: Add support of creating multiple iommus from iommufd

[Samiullah Khawaja]

IOMMUFD allows creating multiple IOAS and HWPTs under one iommufd, Add
API to init a struct iommu using an already opened iommufd. The API
internally creates a new IOAS and also a new HWPT as an option based on
the flags passed to the function.

Signed-off-by: Samiullah Khawaja <skhawaja@google.com>
---
 .../vfio/lib/include/libvfio/iommu.h          |  5 ++
 .../lib/include/libvfio/vfio_pci_device.h     |  2 +
 tools/testing/selftests/vfio/lib/iommu.c      | 62 +++++++++++++++++--
 .../selftests/vfio/lib/vfio_pci_device.c      | 22 ++++++-
 4 files changed, 84 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/vfio/lib/include/libvfio/iommu.h b/tools/testing/selftests/vfio/lib/include/libvfio/iommu.h
index e9a3386a4719..89249a294920 100644
--- a/tools/testing/selftests/vfio/lib/include/libvfio/iommu.h
+++ b/tools/testing/selftests/vfio/lib/include/libvfio/iommu.h
@@ -9,6 +9,9 @@
 
 typedef u64 iova_t;
 
+/* Create IOMMU with page tables */
+#define IOMMUFD_IOMMU_INIT_CREATE_PT 1
+
 struct iommu_mode {
 	const char *name;
 	const char *container_path;
@@ -29,10 +32,12 @@ struct iommu {
 	int container_fd;
 	int iommufd;
 	u32 ioas_id;
+	u32 hwpt_id;
 	struct list_head dma_regions;
 };
 
 struct iommu *iommu_init(const char *iommu_mode);
+struct iommu *iommufd_iommu_init(int iommufd, u32 dev_id, u32 flags);
 void iommu_cleanup(struct iommu *iommu);
 
 int __iommu_map(struct iommu *iommu, struct dma_region *region);
diff --git a/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h b/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h
index 2858885a89bb..1143ceb6a9b8 100644
--- a/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h
+++ b/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h
@@ -19,6 +19,7 @@ struct vfio_pci_device {
 	const char *bdf;
 	int fd;
 	int group_fd;
+	u32 dev_id;
 
 	struct iommu *iommu;
 
@@ -65,6 +66,7 @@ void vfio_pci_config_access(struct vfio_pci_device *device, bool write,
 #define vfio_pci_config_writew(_d, _o, _v) vfio_pci_config_write(_d, _o, _v, u16)
 #define vfio_pci_config_writel(_d, _o, _v) vfio_pci_config_write(_d, _o, _v, u32)
 
+void vfio_pci_device_attach_iommu(struct vfio_pci_device *device, struct iommu *iommu);
 void vfio_pci_irq_enable(struct vfio_pci_device *device, u32 index,
 			 u32 vector, int count);
 void vfio_pci_irq_disable(struct vfio_pci_device *device, u32 index);
diff --git a/tools/testing/selftests/vfio/lib/iommu.c b/tools/testing/selftests/vfio/lib/iommu.c
index 035dac069d60..644c049cf9f0 100644
--- a/tools/testing/selftests/vfio/lib/iommu.c
+++ b/tools/testing/selftests/vfio/lib/iommu.c
@@ -408,6 +408,18 @@ struct iommu_iova_range *iommu_iova_ranges(struct iommu *iommu, u32 *nranges)
 	return ranges;
 }
 
+static u32 iommufd_hwpt_alloc(struct iommu *iommu, u32 dev_id)
+{
+	struct iommu_hwpt_alloc args = {
+		.size = sizeof(args),
+		.pt_id = iommu->ioas_id,
+		.dev_id = dev_id,
+	};
+
+	ioctl_assert(iommu->iommufd, IOMMU_HWPT_ALLOC, &args);
+	return args.out_hwpt_id;
+}
+
 static u32 iommufd_ioas_alloc(int iommufd)
 {
 	struct iommu_ioas_alloc args = {
@@ -418,11 +430,9 @@ static u32 iommufd_ioas_alloc(int iommufd)
 	return args.out_ioas_id;
 }
 
-struct iommu *iommu_init(const char *iommu_mode)
+static struct iommu *iommu_alloc(const char *iommu_mode)
 {
-	const char *container_path;
 	struct iommu *iommu;
-	int version;
 
 	iommu = calloc(1, sizeof(*iommu));
 	VFIO_ASSERT_NOT_NULL(iommu);
@@ -430,6 +440,16 @@ struct iommu *iommu_init(const char *iommu_mode)
 	INIT_LIST_HEAD(&iommu->dma_regions);
 
 	iommu->mode = lookup_iommu_mode(iommu_mode);
+	return iommu;
+}
+
+struct iommu *iommu_init(const char *iommu_mode)
+{
+	const char *container_path;
+	struct iommu *iommu;
+	int version;
+
+	iommu = iommu_alloc(iommu_mode);
 
 	container_path = iommu->mode->container_path;
 	if (container_path) {
@@ -453,10 +473,44 @@ struct iommu *iommu_init(const char *iommu_mode)
 	return iommu;
 }
 
+struct iommu *iommufd_iommu_init(int iommufd, u32 dev_id, u32 flags)
+{
+	struct iommu *iommu;
+
+	iommu = iommu_alloc("iommufd");
+
+	iommu->iommufd = dup(iommufd);
+	VFIO_ASSERT_GT(iommu->iommufd, 0);
+
+	iommu->ioas_id = iommufd_ioas_alloc(iommu->iommufd);
+
+	if (flags & IOMMUFD_IOMMU_INIT_CREATE_PT)
+		iommu->hwpt_id = iommufd_hwpt_alloc(iommu, dev_id);
+
+	return iommu;
+}
+
+static void iommufd_cleanup(struct iommu *iommu)
+{
+	struct iommu_destroy args = {
+		.size = sizeof(args),
+	};
+
+	if (iommu->hwpt_id) {
+		args.id = iommu->hwpt_id;
+		ioctl_assert(iommu->iommufd, IOMMU_DESTROY, &args);
+	}
+
+	args.id = iommu->ioas_id;
+	ioctl_assert(iommu->iommufd, IOMMU_DESTROY, &args);
+
+	VFIO_ASSERT_EQ(close(iommu->iommufd), 0);
+}
+
 void iommu_cleanup(struct iommu *iommu)
 {
 	if (iommu->iommufd)
-		VFIO_ASSERT_EQ(close(iommu->iommufd), 0);
+		iommufd_cleanup(iommu);
 	else
 		VFIO_ASSERT_EQ(close(iommu->container_fd), 0);
 
diff --git a/tools/testing/selftests/vfio/lib/vfio_pci_device.c b/tools/testing/selftests/vfio/lib/vfio_pci_device.c
index fc75e04ef010..e2b71fe63cae 100644
--- a/tools/testing/selftests/vfio/lib/vfio_pci_device.c
+++ b/tools/testing/selftests/vfio/lib/vfio_pci_device.c
@@ -322,7 +322,7 @@ const char *vfio_pci_get_cdev_path(const char *bdf)
 	return cdev_path;
 }
 
-static void vfio_device_bind_iommufd(int device_fd, int iommufd)
+static int vfio_device_bind_iommufd(int device_fd, int iommufd)
 {
 	struct vfio_device_bind_iommufd args = {
 		.argsz = sizeof(args),
@@ -330,6 +330,7 @@ static void vfio_device_bind_iommufd(int device_fd, int iommufd)
 	};
 
 	ioctl_assert(device_fd, VFIO_DEVICE_BIND_IOMMUFD, &args);
+	return args.out_devid;
 }
 
 static void vfio_device_attach_iommufd_pt(int device_fd, u32 pt_id)
@@ -342,6 +343,21 @@ static void vfio_device_attach_iommufd_pt(int device_fd, u32 pt_id)
 	ioctl_assert(device_fd, VFIO_DEVICE_ATTACH_IOMMUFD_PT, &args);
 }
 
+void vfio_pci_device_attach_iommu(struct vfio_pci_device *device, struct iommu *iommu)
+{
+	u32 pt_id = iommu->ioas_id;
+
+	/* Only iommufd supports changing struct iommu attachments */
+	VFIO_ASSERT_TRUE(iommu->iommufd);
+
+	if (iommu->hwpt_id)
+		pt_id = iommu->hwpt_id;
+
+	VFIO_ASSERT_NE(pt_id, 0);
+	vfio_device_attach_iommufd_pt(device->fd, pt_id);
+	device->iommu = iommu;
+}
+
 static void vfio_pci_iommufd_setup(struct vfio_pci_device *device, const char *bdf)
 {
 	const char *cdev_path = vfio_pci_get_cdev_path(bdf);
@@ -350,8 +366,8 @@ static void vfio_pci_iommufd_setup(struct vfio_pci_device *device, const char *b
 	VFIO_ASSERT_GE(device->fd, 0);
 	free((void *)cdev_path);
 
-	vfio_device_bind_iommufd(device->fd, device->iommu->iommufd);
-	vfio_device_attach_iommufd_pt(device->fd, device->iommu->ioas_id);
+	device->dev_id = vfio_device_bind_iommufd(device->fd, device->iommu->iommufd);
+	vfio_pci_device_attach_iommu(device, device->iommu);
 }
 
 struct vfio_pci_device *vfio_pci_device_init(const char *bdf, struct iommu *iommu)
-- 
2.54.0.545.g6539524ca2-goog

[PATCH 2/2] vfio: selftests: Add iommufd multi iommu test

[Samiullah Khawaja]

Add a test for iommufd to verify creation of multiple iommus using an
already setup iommufd and switch between them.

Signed-off-by: Samiullah Khawaja <skhawaja@google.com>
---
 tools/testing/selftests/vfio/Makefile         |   1 +
 .../vfio/vfio_iommufd_multi_iommu_test.c      | 203 ++++++++++++++++++
 2 files changed, 204 insertions(+)
 create mode 100644 tools/testing/selftests/vfio/vfio_iommufd_multi_iommu_test.c

diff --git a/tools/testing/selftests/vfio/Makefile b/tools/testing/selftests/vfio/Makefile
index 0684932d91bf..24bdeaad590f 100644
--- a/tools/testing/selftests/vfio/Makefile
+++ b/tools/testing/selftests/vfio/Makefile
@@ -8,6 +8,7 @@ else
 CFLAGS = $(KHDR_INCLUDES)
 TEST_GEN_PROGS += vfio_dma_mapping_test
 TEST_GEN_PROGS += vfio_dma_mapping_mmio_test
+TEST_GEN_PROGS += vfio_iommufd_multi_iommu_test
 TEST_GEN_PROGS += vfio_iommufd_setup_test
 TEST_GEN_PROGS += vfio_pci_device_test
 TEST_GEN_PROGS += vfio_pci_device_init_perf_test
diff --git a/tools/testing/selftests/vfio/vfio_iommufd_multi_iommu_test.c b/tools/testing/selftests/vfio/vfio_iommufd_multi_iommu_test.c
new file mode 100644
index 000000000000..7199c662637c
--- /dev/null
+++ b/tools/testing/selftests/vfio/vfio_iommufd_multi_iommu_test.c
@@ -0,0 +1,203 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+
+#include <linux/sizes.h>
+#include <linux/vfio.h>
+
+#include <libvfio.h>
+
+#include "kselftest_harness.h"
+
+static const char *device_bdf;
+
+#define IOMMU_DEFAULT 0
+#define IOMMU_WITH_PT 1
+#define IOMMU_WITHOUT_PT 2
+
+static void region_setup(struct iommu *iommu,
+			 struct iova_allocator *iova_allocator,
+			 struct dma_region *region, u64 size)
+{
+	const int flags = MAP_SHARED | MAP_ANONYMOUS;
+	const int prot = PROT_READ | PROT_WRITE;
+	void *vaddr;
+
+	vaddr = mmap(NULL, size, prot, flags, -1, 0);
+	VFIO_ASSERT_NE(vaddr, MAP_FAILED);
+
+	region->vaddr = vaddr;
+	region->iova = iova_allocator_alloc(iova_allocator, size);
+	region->size = size;
+
+	iommu_map(iommu, region);
+}
+
+static void region_teardown(struct iommu *iommu, struct dma_region *region)
+{
+	iommu_unmap(iommu, region);
+	VFIO_ASSERT_EQ(munmap(region->vaddr, region->size), 0);
+}
+
+FIXTURE(vfio_iommufd_multi_iommu_test) {
+	struct iommu *iommu;
+	struct vfio_pci_device *device;
+	struct iova_allocator *iova_allocator;
+	struct dma_region memcpy_region;
+	void *vaddr;
+
+	u64 size;
+	void *src;
+	void *dst;
+	iova_t src_iova;
+	iova_t dst_iova;
+};
+
+FIXTURE_SETUP(vfio_iommufd_multi_iommu_test)
+{
+	struct vfio_pci_driver *driver;
+
+	self->iommu = iommu_init("iommufd");
+	self->device = vfio_pci_device_init(device_bdf, self->iommu);
+	self->iova_allocator = iova_allocator_init(self->iommu);
+
+	driver = &self->device->driver;
+
+	region_setup(self->iommu, self->iova_allocator, &self->memcpy_region, SZ_1G);
+	region_setup(self->iommu, self->iova_allocator, &driver->region, SZ_2M);
+
+	if (driver->ops)
+		vfio_pci_driver_init(self->device);
+
+	self->size = self->memcpy_region.size / 2;
+	self->src = self->memcpy_region.vaddr;
+	self->dst = self->src + self->size;
+
+	self->src_iova = to_iova(self->device, self->src);
+	self->dst_iova = to_iova(self->device, self->dst);
+}
+
+FIXTURE_TEARDOWN(vfio_iommufd_multi_iommu_test)
+{
+	struct vfio_pci_driver *driver = &self->device->driver;
+
+	if (driver->ops)
+		vfio_pci_driver_remove(self->device);
+
+	region_teardown(self->iommu, &self->memcpy_region);
+	region_teardown(self->iommu, &driver->region);
+
+	iova_allocator_cleanup(self->iova_allocator);
+	vfio_pci_device_cleanup(self->device);
+	iommu_cleanup(self->iommu);
+}
+
+FIXTURE_VARIANT(vfio_iommufd_multi_iommu_test) {
+	u32 start_iommu;
+	u32 end_iommu;
+};
+
+#define ADD_IOMMU_VARIANT(S, E) \
+	FIXTURE_VARIANT_ADD(vfio_iommufd_multi_iommu_test, S##_to_##E) { \
+		.start_iommu = IOMMU_##S, \
+		.end_iommu = IOMMU_##E \
+	};
+
+#define ADD_ALL_VARIANTS(S) \
+	ADD_IOMMU_VARIANT(S, DEFAULT) \
+	ADD_IOMMU_VARIANT(S, WITH_PT) \
+	ADD_IOMMU_VARIANT(S, WITHOUT_PT)
+
+ADD_ALL_VARIANTS(DEFAULT)
+ADD_ALL_VARIANTS(WITH_PT)
+ADD_ALL_VARIANTS(WITHOUT_PT)
+
+static struct iommu *setup_variant_iommu(struct iommu *fixture_iommu,
+					 u32 dev_id, u32 type)
+{
+	switch (type) {
+	case IOMMU_WITH_PT:
+		return iommufd_iommu_init(fixture_iommu->iommufd, dev_id,
+					  IOMMUFD_IOMMU_INIT_CREATE_PT);
+	case IOMMU_WITHOUT_PT:
+		return iommufd_iommu_init(fixture_iommu->iommufd, dev_id, 0);
+	default:
+		return fixture_iommu;
+	}
+}
+
+static void test_memcpy(struct vfio_pci_device *device, void *src, void *dst,
+			iova_t src_iova, iova_t dst_iova, u64 size, char val)
+{
+	if (!device->driver.ops)
+		return;
+
+	memset(src, val, size);
+	memset(dst, 0, size);
+
+	vfio_pci_driver_memcpy_start(device, src_iova, dst_iova, size, 100);
+	VFIO_ASSERT_EQ(vfio_pci_driver_memcpy_wait(device), 0);
+	VFIO_ASSERT_EQ(memcmp(src, dst, size), 0);
+}
+
+TEST_F(vfio_iommufd_multi_iommu_test, memcpy)
+{
+	struct dma_region memcpy_region1, driver_region1;
+	struct dma_region memcpy_region2, driver_region2;
+	struct iommu *iommu1;
+	struct iommu *iommu2;
+
+	iommu1 = setup_variant_iommu(self->iommu, self->device->dev_id,
+				     variant->start_iommu);
+	if (iommu1 != self->iommu) {
+		memcpy_region1 = self->memcpy_region;
+		driver_region1 = self->device->driver.region;
+
+		iommu_map(iommu1, &memcpy_region1);
+		iommu_map(iommu1, &driver_region1);
+
+		vfio_pci_device_attach_iommu(self->device, iommu1);
+	}
+
+	test_memcpy(self->device, self->src, self->dst, self->src_iova,
+		    self->dst_iova, self->size, 'x');
+
+	iommu2 = setup_variant_iommu(self->iommu, self->device->dev_id,
+				     variant->end_iommu);
+	if (iommu2 != self->iommu) {
+		memcpy_region2 = self->memcpy_region;
+		driver_region2 = self->device->driver.region;
+
+		iommu_map(iommu2, &memcpy_region2);
+		iommu_map(iommu2, &driver_region2);
+	}
+
+	vfio_pci_device_attach_iommu(self->device, iommu2);
+	test_memcpy(self->device, self->src, self->dst, self->src_iova,
+		    self->dst_iova, self->size, 'a');
+
+	vfio_pci_device_attach_iommu(self->device, iommu1);
+	test_memcpy(self->device, self->src, self->dst, self->src_iova,
+		    self->dst_iova, self->size, '1');
+
+	if (iommu1 != self->iommu) {
+		/* attach back to default iommu for cleanup */
+		vfio_pci_device_attach_iommu(self->device, self->iommu);
+		iommu_unmap(iommu1, &memcpy_region1);
+		iommu_unmap(iommu1, &driver_region1);
+		iommu_cleanup(iommu1);
+	}
+
+	if (iommu2 != self->iommu) {
+		iommu_unmap(iommu2, &memcpy_region2);
+		iommu_unmap(iommu2, &driver_region2);
+		iommu_cleanup(iommu2);
+	}
+}
+
+int main(int argc, char *argv[])
+{
+	device_bdf = vfio_selftests_get_bdf(&argc, argv);
+
+	return test_harness_run(argc, argv);
+}
-- 
2.54.0.545.g6539524ca2-goog

Re: [PATCH 1/2] vfio: selftests: Add support of creating multiple iommus from iommufd

[David Matlack]

On 2026-05-05 10:14 PM, Samiullah Khawaja wrote:
> IOMMUFD allows creating multiple IOAS and HWPTs under one iommufd, Add
> API to init a struct iommu using an already opened iommufd. The API
> internally creates a new IOAS and also a new HWPT as an option based on
> the flags passed to the function.
> 
> Signed-off-by: Samiullah Khawaja <skhawaja@google.com>
> ---
>  .../vfio/lib/include/libvfio/iommu.h          |  5 ++
>  .../lib/include/libvfio/vfio_pci_device.h     |  2 +
>  tools/testing/selftests/vfio/lib/iommu.c      | 62 +++++++++++++++++--
>  .../selftests/vfio/lib/vfio_pci_device.c      | 22 ++++++-
>  4 files changed, 84 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/testing/selftests/vfio/lib/include/libvfio/iommu.h b/tools/testing/selftests/vfio/lib/include/libvfio/iommu.h
> index e9a3386a4719..89249a294920 100644
> --- a/tools/testing/selftests/vfio/lib/include/libvfio/iommu.h
> +++ b/tools/testing/selftests/vfio/lib/include/libvfio/iommu.h
> @@ -9,6 +9,9 @@
>  
>  typedef u64 iova_t;
>  
> +/* Create IOMMU with page tables */
> +#define IOMMUFD_IOMMU_INIT_CREATE_PT 1
> +
>  struct iommu_mode {
>  	const char *name;
>  	const char *container_path;
> @@ -29,10 +32,12 @@ struct iommu {
>  	int container_fd;
>  	int iommufd;
>  	u32 ioas_id;
> +	u32 hwpt_id;
>  	struct list_head dma_regions;
>  };
>  
>  struct iommu *iommu_init(const char *iommu_mode);
> +struct iommu *iommufd_iommu_init(int iommufd, u32 dev_id, u32 flags);
>  void iommu_cleanup(struct iommu *iommu);
>  
>  int __iommu_map(struct iommu *iommu, struct dma_region *region);
> diff --git a/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h b/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h
> index 2858885a89bb..1143ceb6a9b8 100644
> --- a/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h
> +++ b/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h
> @@ -19,6 +19,7 @@ struct vfio_pci_device {
>  	const char *bdf;
>  	int fd;
>  	int group_fd;
> +	u32 dev_id;

Please introduce an initialize this field in its own patch and, in the
commit message, explain why it is being added and  how it will be used.

>  
>  	struct iommu *iommu;
>  
> @@ -65,6 +66,7 @@ void vfio_pci_config_access(struct vfio_pci_device *device, bool write,
>  #define vfio_pci_config_writew(_d, _o, _v) vfio_pci_config_write(_d, _o, _v, u16)
>  #define vfio_pci_config_writel(_d, _o, _v) vfio_pci_config_write(_d, _o, _v, u32)
>  
> +void vfio_pci_device_attach_iommu(struct vfio_pci_device *device, struct iommu *iommu);
>  void vfio_pci_irq_enable(struct vfio_pci_device *device, u32 index,
>  			 u32 vector, int count);
>  void vfio_pci_irq_disable(struct vfio_pci_device *device, u32 index);
> diff --git a/tools/testing/selftests/vfio/lib/iommu.c b/tools/testing/selftests/vfio/lib/iommu.c
> index 035dac069d60..644c049cf9f0 100644
> --- a/tools/testing/selftests/vfio/lib/iommu.c
> +++ b/tools/testing/selftests/vfio/lib/iommu.c
> @@ -408,6 +408,18 @@ struct iommu_iova_range *iommu_iova_ranges(struct iommu *iommu, u32 *nranges)
>  	return ranges;
>  }
>  
> +static u32 iommufd_hwpt_alloc(struct iommu *iommu, u32 dev_id)
> +{
> +	struct iommu_hwpt_alloc args = {
> +		.size = sizeof(args),
> +		.pt_id = iommu->ioas_id,
> +		.dev_id = dev_id,
> +	};
> +
> +	ioctl_assert(iommu->iommufd, IOMMU_HWPT_ALLOC, &args);
> +	return args.out_hwpt_id;
> +}
> +
>  static u32 iommufd_ioas_alloc(int iommufd)
>  {
>  	struct iommu_ioas_alloc args = {
> @@ -418,11 +430,9 @@ static u32 iommufd_ioas_alloc(int iommufd)
>  	return args.out_ioas_id;
>  }
>  
> -struct iommu *iommu_init(const char *iommu_mode)
> +static struct iommu *iommu_alloc(const char *iommu_mode)
>  {
> -	const char *container_path;
>  	struct iommu *iommu;
> -	int version;
>  
>  	iommu = calloc(1, sizeof(*iommu));
>  	VFIO_ASSERT_NOT_NULL(iommu);
> @@ -430,6 +440,16 @@ struct iommu *iommu_init(const char *iommu_mode)
>  	INIT_LIST_HEAD(&iommu->dma_regions);
>  
>  	iommu->mode = lookup_iommu_mode(iommu_mode);
> +	return iommu;
> +}
> +
> +struct iommu *iommu_init(const char *iommu_mode)
> +{
> +	const char *container_path;
> +	struct iommu *iommu;
> +	int version;
> +
> +	iommu = iommu_alloc(iommu_mode);
>  
>  	container_path = iommu->mode->container_path;
>  	if (container_path) {
> @@ -453,10 +473,44 @@ struct iommu *iommu_init(const char *iommu_mode)
>  	return iommu;
>  }
>  
> +struct iommu *iommufd_iommu_init(int iommufd, u32 dev_id, u32 flags)
> +{
> +	struct iommu *iommu;
> +
> +	iommu = iommu_alloc("iommufd");

Use MODE_IOMMUFD instead of string literal.

> +
> +	iommu->iommufd = dup(iommufd);
> +	VFIO_ASSERT_GT(iommu->iommufd, 0);
> +
> +	iommu->ioas_id = iommufd_ioas_alloc(iommu->iommufd);

Please avoid duplicating this code. e.g. Something like this:

diff --git a/tools/testing/selftests/vfio/lib/iommu.c b/tools/testing/selftests/vfio/lib/iommu.c
index 644c049cf9f0..4909cda5c840 100644
--- a/tools/testing/selftests/vfio/lib/iommu.c
+++ b/tools/testing/selftests/vfio/lib/iommu.c
@@ -443,6 +443,19 @@ static struct iommu *iommu_alloc(const char *iommu_mode)
        return iommu;
 }

+static void iommufd_init(struct iommu *iommu, int iommufd)
+{
+       /*
+        * Require device->iommufd to be >0 so that a simple non-0 check can be
+        * used to check if iommufd is enabled. In practice open() will never
+        * return 0 unless stdin is closed.
+        */
+       VFIO_ASSERT_GT(iommufd, 0);
+
+       iommu->iommufd = iommufd;
+       iommu->ioas_id = iommufd_ioas_alloc(iommu->iommufd);
+}
+
 struct iommu *iommu_init(const char *iommu_mode)
 {
        const char *container_path;
@@ -459,15 +472,7 @@ struct iommu *iommu_init(const char *iommu_mode)
                version = ioctl(iommu->container_fd, VFIO_GET_API_VERSION);
                VFIO_ASSERT_EQ(version, VFIO_API_VERSION, "Unsupported version: %d\n", version);
        } else {
-               /*
-                * Require device->iommufd to be >0 so that a simple non-0 check can be
-                * used to check if iommufd is enabled. In practice open() will never
-                * return 0 unless stdin is closed.
-                */
-               iommu->iommufd = open("/dev/iommu", O_RDWR);
-               VFIO_ASSERT_GT(iommu->iommufd, 0);
-
-               iommu->ioas_id = iommufd_ioas_alloc(iommu->iommufd);
+               iommufd_init(iommu, open("/dev/iommu", O_RDWR));
        }

        return iommu;
@@ -478,11 +483,7 @@ struct iommu *iommufd_iommu_init(int iommufd, u32 dev_id, u32 flags)
        struct iommu *iommu;

        iommu = iommu_alloc("iommufd");
-
-       iommu->iommufd = dup(iommufd);
-       VFIO_ASSERT_GT(iommu->iommufd, 0);
-
-       iommu->ioas_id = iommufd_ioas_alloc(iommu->iommufd);
+       iommufd_init(iommu, dup(iommufd));

        if (flags & IOMMUFD_IOMMU_INIT_CREATE_PT)
                iommu->hwpt_id = iommufd_hwpt_alloc(iommu, dev_id);

> +
> +	if (flags & IOMMUFD_IOMMU_INIT_CREATE_PT)
> +		iommu->hwpt_id = iommufd_hwpt_alloc(iommu, dev_id);

Does this need to be part of iommufd_iommu_init()? Maybe it would be
better to expose a separate helper to allocate a HWPT for a given struct
iommu *.

This would enable use of HWPTs in iommus constructed by iommu_init() as
well, which someone may want to do in the future.

If you go this route, please introduce this in its own commit.

> +
> +	return iommu;
> +}
> +
> +static void iommufd_cleanup(struct iommu *iommu)
> +{
> +	struct iommu_destroy args = {
> +		.size = sizeof(args),
> +	};
> +
> +	if (iommu->hwpt_id) {
> +		args.id = iommu->hwpt_id;
> +		ioctl_assert(iommu->iommufd, IOMMU_DESTROY, &args);
> +	}
> +
> +	args.id = iommu->ioas_id;
> +	ioctl_assert(iommu->iommufd, IOMMU_DESTROY, &args);


Please create a helper function to do IOMMU_DESTROY ioctl. Then here you
can just do:

  if (iommu->hwpt_id)
          iommufd_iommu_destroy(iommu, iommu->hwpt_id);

  iommfd_iommu_destroy(iommu, iommu->ioas_id);

> +
> +	VFIO_ASSERT_EQ(close(iommu->iommufd), 0);
> +}
> +
>  void iommu_cleanup(struct iommu *iommu)
>  {
>  	if (iommu->iommufd)
> -		VFIO_ASSERT_EQ(close(iommu->iommufd), 0);
> +		iommufd_cleanup(iommu);
>  	else
>  		VFIO_ASSERT_EQ(close(iommu->container_fd), 0);
>  
> diff --git a/tools/testing/selftests/vfio/lib/vfio_pci_device.c b/tools/testing/selftests/vfio/lib/vfio_pci_device.c
> index fc75e04ef010..e2b71fe63cae 100644
> --- a/tools/testing/selftests/vfio/lib/vfio_pci_device.c
> +++ b/tools/testing/selftests/vfio/lib/vfio_pci_device.c
> @@ -322,7 +322,7 @@ const char *vfio_pci_get_cdev_path(const char *bdf)
>  	return cdev_path;
>  }
>  
> -static void vfio_device_bind_iommufd(int device_fd, int iommufd)
> +static int vfio_device_bind_iommufd(int device_fd, int iommufd)
>  {
>  	struct vfio_device_bind_iommufd args = {
>  		.argsz = sizeof(args),
> @@ -330,6 +330,7 @@ static void vfio_device_bind_iommufd(int device_fd, int iommufd)
>  	};
>  
>  	ioctl_assert(device_fd, VFIO_DEVICE_BIND_IOMMUFD, &args);
> +	return args.out_devid;
>  }
>  
>  static void vfio_device_attach_iommufd_pt(int device_fd, u32 pt_id)
> @@ -342,6 +343,21 @@ static void vfio_device_attach_iommufd_pt(int device_fd, u32 pt_id)
>  	ioctl_assert(device_fd, VFIO_DEVICE_ATTACH_IOMMUFD_PT, &args);
>  }
>  
> +void vfio_pci_device_attach_iommu(struct vfio_pci_device *device, struct iommu *iommu)
> +{
> +	u32 pt_id = iommu->ioas_id;
> +
> +	/* Only iommufd supports changing struct iommu attachments */
> +	VFIO_ASSERT_TRUE(iommu->iommufd);
> +
> +	if (iommu->hwpt_id)
> +		pt_id = iommu->hwpt_id;

nit: This can be folded into the variable declaration.

  const u32 pt_id = iommu->hwpt_id ?: iommu->ioas_id;

> +
> +	VFIO_ASSERT_NE(pt_id, 0);

Why is this check needed?

> +	vfio_device_attach_iommufd_pt(device->fd, pt_id);
> +	device->iommu = iommu;
> +}

Please introduce vfio_pci_device_attach_iommu() in its own patch.

> +
>  static void vfio_pci_iommufd_setup(struct vfio_pci_device *device, const char *bdf)
>  {
>  	const char *cdev_path = vfio_pci_get_cdev_path(bdf);
> @@ -350,8 +366,8 @@ static void vfio_pci_iommufd_setup(struct vfio_pci_device *device, const char *b
>  	VFIO_ASSERT_GE(device->fd, 0);
>  	free((void *)cdev_path);
>  
> -	vfio_device_bind_iommufd(device->fd, device->iommu->iommufd);
> -	vfio_device_attach_iommufd_pt(device->fd, device->iommu->ioas_id);
> +	device->dev_id = vfio_device_bind_iommufd(device->fd, device->iommu->iommufd);
> +	vfio_pci_device_attach_iommu(device, device->iommu);
>  }
>  
>  struct vfio_pci_device *vfio_pci_device_init(const char *bdf, struct iommu *iommu)
> -- 
> 2.54.0.545.g6539524ca2-goog
> 

Re: [PATCH 2/2] vfio: selftests: Add iommufd multi iommu test

[David Matlack]

On 2026-05-05 10:14 PM, Samiullah Khawaja wrote:
> Add a test for iommufd to verify creation of multiple iommus using an
> already setup iommufd and switch between them.
> 
> Signed-off-by: Samiullah Khawaja <skhawaja@google.com>
> ---
>  tools/testing/selftests/vfio/Makefile         |   1 +
>  .../vfio/vfio_iommufd_multi_iommu_test.c      | 203 ++++++++++++++++++
>  2 files changed, 204 insertions(+)
>  create mode 100644 tools/testing/selftests/vfio/vfio_iommufd_multi_iommu_test.c
> 
> diff --git a/tools/testing/selftests/vfio/Makefile b/tools/testing/selftests/vfio/Makefile
> index 0684932d91bf..24bdeaad590f 100644
> --- a/tools/testing/selftests/vfio/Makefile
> +++ b/tools/testing/selftests/vfio/Makefile
> @@ -8,6 +8,7 @@ else
>  CFLAGS = $(KHDR_INCLUDES)
>  TEST_GEN_PROGS += vfio_dma_mapping_test
>  TEST_GEN_PROGS += vfio_dma_mapping_mmio_test
> +TEST_GEN_PROGS += vfio_iommufd_multi_iommu_test
>  TEST_GEN_PROGS += vfio_iommufd_setup_test
>  TEST_GEN_PROGS += vfio_pci_device_test
>  TEST_GEN_PROGS += vfio_pci_device_init_perf_test
> diff --git a/tools/testing/selftests/vfio/vfio_iommufd_multi_iommu_test.c b/tools/testing/selftests/vfio/vfio_iommufd_multi_iommu_test.c
> new file mode 100644
> index 000000000000..7199c662637c
> --- /dev/null
> +++ b/tools/testing/selftests/vfio/vfio_iommufd_multi_iommu_test.c
> @@ -0,0 +1,203 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +#include <sys/ioctl.h>
> +#include <sys/mman.h>
> +
> +#include <linux/sizes.h>
> +#include <linux/vfio.h>
> +
> +#include <libvfio.h>
> +
> +#include "kselftest_harness.h"
> +
> +static const char *device_bdf;
> +
> +#define IOMMU_DEFAULT 0
> +#define IOMMU_WITH_PT 1
> +#define IOMMU_WITHOUT_PT 2
> +
> +static void region_setup(struct iommu *iommu,
> +			 struct iova_allocator *iova_allocator,
> +			 struct dma_region *region, u64 size)
> +{
> +	const int flags = MAP_SHARED | MAP_ANONYMOUS;
> +	const int prot = PROT_READ | PROT_WRITE;
> +	void *vaddr;
> +
> +	vaddr = mmap(NULL, size, prot, flags, -1, 0);
> +	VFIO_ASSERT_NE(vaddr, MAP_FAILED);
> +
> +	region->vaddr = vaddr;
> +	region->iova = iova_allocator_alloc(iova_allocator, size);
> +	region->size = size;
> +
> +	iommu_map(iommu, region);
> +}
> +
> +static void region_teardown(struct iommu *iommu, struct dma_region *region)
> +{
> +	iommu_unmap(iommu, region);
> +	VFIO_ASSERT_EQ(munmap(region->vaddr, region->size), 0);
> +}

Can you create library helpers in the library to share with
vfio_pci_driver_test.c?

  dma_region_setup()
  dma_region_teardown()

> +
> +FIXTURE(vfio_iommufd_multi_iommu_test) {
> +	struct iommu *iommu;
> +	struct vfio_pci_device *device;
> +	struct iova_allocator *iova_allocator;
> +	struct dma_region memcpy_region;
> +	void *vaddr;
> +
> +	u64 size;
> +	void *src;
> +	void *dst;
> +	iova_t src_iova;
> +	iova_t dst_iova;
> +};
> +
> +FIXTURE_SETUP(vfio_iommufd_multi_iommu_test)
> +{
> +	struct vfio_pci_driver *driver;
> +
> +	self->iommu = iommu_init("iommufd");

MODE_IOMMUFD

> +	self->device = vfio_pci_device_init(device_bdf, self->iommu);
> +	self->iova_allocator = iova_allocator_init(self->iommu);
> +
> +	driver = &self->device->driver;
> +
> +	region_setup(self->iommu, self->iova_allocator, &self->memcpy_region, SZ_1G);
> +	region_setup(self->iommu, self->iova_allocator, &driver->region, SZ_2M);
> +
> +	if (driver->ops)
> +		vfio_pci_driver_init(self->device);
> +
> +	self->size = self->memcpy_region.size / 2;
> +	self->src = self->memcpy_region.vaddr;
> +	self->dst = self->src + self->size;
> +
> +	self->src_iova = to_iova(self->device, self->src);
> +	self->dst_iova = to_iova(self->device, self->dst);
> +}
> +
> +FIXTURE_TEARDOWN(vfio_iommufd_multi_iommu_test)
> +{
> +	struct vfio_pci_driver *driver = &self->device->driver;
> +
> +	if (driver->ops)
> +		vfio_pci_driver_remove(self->device);
> +
> +	region_teardown(self->iommu, &self->memcpy_region);
> +	region_teardown(self->iommu, &driver->region);
> +
> +	iova_allocator_cleanup(self->iova_allocator);
> +	vfio_pci_device_cleanup(self->device);
> +	iommu_cleanup(self->iommu);
> +}
> +
> +FIXTURE_VARIANT(vfio_iommufd_multi_iommu_test) {
> +	u32 start_iommu;
> +	u32 end_iommu;
> +};
> +
> +#define ADD_IOMMU_VARIANT(S, E) \
> +	FIXTURE_VARIANT_ADD(vfio_iommufd_multi_iommu_test, S##_to_##E) { \
> +		.start_iommu = IOMMU_##S, \
> +		.end_iommu = IOMMU_##E \
> +	};
> +
> +#define ADD_ALL_VARIANTS(S) \
> +	ADD_IOMMU_VARIANT(S, DEFAULT) \
> +	ADD_IOMMU_VARIANT(S, WITH_PT) \
> +	ADD_IOMMU_VARIANT(S, WITHOUT_PT)
> +
> +ADD_ALL_VARIANTS(DEFAULT)
> +ADD_ALL_VARIANTS(WITH_PT)
> +ADD_ALL_VARIANTS(WITHOUT_PT)
> +
> +static struct iommu *setup_variant_iommu(struct iommu *fixture_iommu,
> +					 u32 dev_id, u32 type)
> +{
> +	switch (type) {
> +	case IOMMU_WITH_PT:
> +		return iommufd_iommu_init(fixture_iommu->iommufd, dev_id,
> +					  IOMMUFD_IOMMU_INIT_CREATE_PT);
> +	case IOMMU_WITHOUT_PT:
> +		return iommufd_iommu_init(fixture_iommu->iommufd, dev_id, 0);
> +	default:
> +		return fixture_iommu;
> +	}
> +}
> +
> +static void test_memcpy(struct vfio_pci_device *device, void *src, void *dst,
> +			iova_t src_iova, iova_t dst_iova, u64 size, char val)
> +{
> +	if (!device->driver.ops)
> +		return;
> +
> +	memset(src, val, size);
> +	memset(dst, 0, size);
> +
> +	vfio_pci_driver_memcpy_start(device, src_iova, dst_iova, size, 100);

Why do 100 copies?

> +	VFIO_ASSERT_EQ(vfio_pci_driver_memcpy_wait(device), 0);
> +	VFIO_ASSERT_EQ(memcmp(src, dst, size), 0);
> +}
> +
> +TEST_F(vfio_iommufd_multi_iommu_test, memcpy)
> +{
> +	struct dma_region memcpy_region1, driver_region1;
> +	struct dma_region memcpy_region2, driver_region2;
> +	struct iommu *iommu1;
> +	struct iommu *iommu2;
> +
> +	iommu1 = setup_variant_iommu(self->iommu, self->device->dev_id,
> +				     variant->start_iommu);
> +	if (iommu1 != self->iommu) {
> +		memcpy_region1 = self->memcpy_region;
> +		driver_region1 = self->device->driver.region;
> +
> +		iommu_map(iommu1, &memcpy_region1);

Can you make a helper to copy dma_region into a new iommu? It should set
up the new struct dma_region based on the old one, re-initialize the
link field, and then call iommu_map().

> +		iommu_map(iommu1, &driver_region1);
> +
> +		vfio_pci_device_attach_iommu(self->device, iommu1);
> +	}
> +
> +	test_memcpy(self->device, self->src, self->dst, self->src_iova,
> +		    self->dst_iova, self->size, 'x');

nit: You can pass in self to avoid unpacking it in every call to
test_memcpy(). The type would be:

  struct _test_data_vfio_iommufd_multi_iommu_test *self

> +
> +	iommu2 = setup_variant_iommu(self->iommu, self->device->dev_id,
> +				     variant->end_iommu);
> +	if (iommu2 != self->iommu) {
> +		memcpy_region2 = self->memcpy_region;
> +		driver_region2 = self->device->driver.region;
> +
> +		iommu_map(iommu2, &memcpy_region2);
> +		iommu_map(iommu2, &driver_region2);
> +	}
> +
> +	vfio_pci_device_attach_iommu(self->device, iommu2);
> +	test_memcpy(self->device, self->src, self->dst, self->src_iova,
> +		    self->dst_iova, self->size, 'a');

test_memcpy() zeroes self->dst every time so do you need to use a
different character for each call?

> +
> +	vfio_pci_device_attach_iommu(self->device, iommu1);
> +	test_memcpy(self->device, self->src, self->dst, self->src_iova,
> +		    self->dst_iova, self->size, '1');
> +
> +	if (iommu1 != self->iommu) {
> +		/* attach back to default iommu for cleanup */
> +		vfio_pci_device_attach_iommu(self->device, self->iommu);
> +		iommu_unmap(iommu1, &memcpy_region1);
> +		iommu_unmap(iommu1, &driver_region1);
> +		iommu_cleanup(iommu1);
> +	}
> +
> +	if (iommu2 != self->iommu) {
> +		iommu_unmap(iommu2, &memcpy_region2);
> +		iommu_unmap(iommu2, &driver_region2);

nit: You don't need to unmap before cleanup. Is this just to exercise
that unmap works on the variant iommus?

> +		iommu_cleanup(iommu2);
> +	}
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	device_bdf = vfio_selftests_get_bdf(&argc, argv);
> +
> +	return test_harness_run(argc, argv);
> +}
> -- 
> 2.54.0.545.g6539524ca2-goog
> 

Re: [PATCH 1/2] vfio: selftests: Add support of creating multiple iommus from iommufd

[Samiullah Khawaja]

On Fri, May 08, 2026 at 06:17:19PM +0000, David Matlack wrote:
>On 2026-05-05 10:14 PM, Samiullah Khawaja wrote:
>> IOMMUFD allows creating multiple IOAS and HWPTs under one iommufd, Add
>> API to init a struct iommu using an already opened iommufd. The API
>> internally creates a new IOAS and also a new HWPT as an option based on
>> the flags passed to the function.
>>
>> Signed-off-by: Samiullah Khawaja <skhawaja@google.com>
>> ---
>>  .../vfio/lib/include/libvfio/iommu.h          |  5 ++
>>  .../lib/include/libvfio/vfio_pci_device.h     |  2 +
>>  tools/testing/selftests/vfio/lib/iommu.c      | 62 +++++++++++++++++--
>>  .../selftests/vfio/lib/vfio_pci_device.c      | 22 ++++++-
>>  4 files changed, 84 insertions(+), 7 deletions(-)
>>

[snip]
>>  int __iommu_map(struct iommu *iommu, struct dma_region *region);
>> diff --git a/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h b/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h
>> index 2858885a89bb..1143ceb6a9b8 100644
>> --- a/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h
>> +++ b/tools/testing/selftests/vfio/lib/include/libvfio/vfio_pci_device.h
>> @@ -19,6 +19,7 @@ struct vfio_pci_device {
>>  	const char *bdf;
>>  	int fd;
>>  	int group_fd;
>> +	u32 dev_id;
>
>Please introduce an initialize this field in its own patch and, in the
>commit message, explain why it is being added and  how it will be used.

Agreed. Will do in next revision.
>
>>
>>  	struct iommu *iommu;
>>
>> @@ -65,6 +66,7 @@ void vfio_pci_config_access(struct vfio_pci_device *device, bool write,
>>  #define vfio_pci_config_writew(_d, _o, _v) vfio_pci_config_write(_d, _o, _v, u16)
>>  #define vfio_pci_config_writel(_d, _o, _v) vfio_pci_config_write(_d, _o, _v, u32)
>>
>> +void vfio_pci_device_attach_iommu(struct vfio_pci_device *device, struct iommu *iommu);
>>  void vfio_pci_irq_enable(struct vfio_pci_device *device, u32 index,
>>  			 u32 vector, int count);
>>  void vfio_pci_irq_disable(struct vfio_pci_device *device, u32 index);
>> diff --git a/tools/testing/selftests/vfio/lib/iommu.c b/tools/testing/selftests/vfio/lib/iommu.c
>> index 035dac069d60..644c049cf9f0 100644
>> --- a/tools/testing/selftests/vfio/lib/iommu.c
>> +++ b/tools/testing/selftests/vfio/lib/iommu.c
>> @@ -408,6 +408,18 @@ struct iommu_iova_range *iommu_iova_ranges(struct iommu *iommu, u32 *nranges)
>>  	return ranges;
>>  }
>>

[snip]
>> +struct iommu *iommufd_iommu_init(int iommufd, u32 dev_id, u32 flags)
>> +{
>> +	struct iommu *iommu;
>> +
>> +	iommu = iommu_alloc("iommufd");
>
>Use MODE_IOMMUFD instead of string literal.

Agreed. Will update this.
>
>> +
>> +	iommu->iommufd = dup(iommufd);
>> +	VFIO_ASSERT_GT(iommu->iommufd, 0);
>> +
>> +	iommu->ioas_id = iommufd_ioas_alloc(iommu->iommufd);
>
>Please avoid duplicating this code. e.g. Something like this:

Agreed. Will update this.
>
>diff --git a/tools/testing/selftests/vfio/lib/iommu.c b/tools/testing/selftests/vfio/lib/iommu.c
>index 644c049cf9f0..4909cda5c840 100644
>--- a/tools/testing/selftests/vfio/lib/iommu.c
>+++ b/tools/testing/selftests/vfio/lib/iommu.c
>@@ -443,6 +443,19 @@ static struct iommu *iommu_alloc(const char *iommu_mode)
>        return iommu;
> }
>
>+static void iommufd_init(struct iommu *iommu, int iommufd)
>+{
>+       /*
>+        * Require device->iommufd to be >0 so that a simple non-0 check can be
>+        * used to check if iommufd is enabled. In practice open() will never
>+        * return 0 unless stdin is closed.
>+        */
>+       VFIO_ASSERT_GT(iommufd, 0);
>+
>+       iommu->iommufd = iommufd;
>+       iommu->ioas_id = iommufd_ioas_alloc(iommu->iommufd);
>+}
>+
> struct iommu *iommu_init(const char *iommu_mode)
> {
>        const char *container_path;
>@@ -459,15 +472,7 @@ struct iommu *iommu_init(const char *iommu_mode)
>                version = ioctl(iommu->container_fd, VFIO_GET_API_VERSION);
>                VFIO_ASSERT_EQ(version, VFIO_API_VERSION, "Unsupported version: %d\n", version);
>        } else {
>-               /*
>-                * Require device->iommufd to be >0 so that a simple non-0 check can be
>-                * used to check if iommufd is enabled. In practice open() will never
>-                * return 0 unless stdin is closed.
>-                */
>-               iommu->iommufd = open("/dev/iommu", O_RDWR);
>-               VFIO_ASSERT_GT(iommu->iommufd, 0);
>-
>-               iommu->ioas_id = iommufd_ioas_alloc(iommu->iommufd);
>+               iommufd_init(iommu, open("/dev/iommu", O_RDWR));
>        }
>
>        return iommu;
>@@ -478,11 +483,7 @@ struct iommu *iommufd_iommu_init(int iommufd, u32 dev_id, u32 flags)
>        struct iommu *iommu;
>
>        iommu = iommu_alloc("iommufd");
>-
>-       iommu->iommufd = dup(iommufd);
>-       VFIO_ASSERT_GT(iommu->iommufd, 0);
>-
>-       iommu->ioas_id = iommufd_ioas_alloc(iommu->iommufd);
>+       iommufd_init(iommu, dup(iommufd));
>
>        if (flags & IOMMUFD_IOMMU_INIT_CREATE_PT)
>                iommu->hwpt_id = iommufd_hwpt_alloc(iommu, dev_id);
>
>> +
>> +	if (flags & IOMMUFD_IOMMU_INIT_CREATE_PT)
>> +		iommu->hwpt_id = iommufd_hwpt_alloc(iommu, dev_id);
>
>Does this need to be part of iommufd_iommu_init()? Maybe it would be
>better to expose a separate helper to allocate a HWPT for a given struct
>iommu *.

Hmm.. that is interesting.. I think we can have following immediate
possibilities when creating a struct iommu (there will be more down the
road, but can be handled in similar way):

- create using struct iommu with a new IOAS.
- create using struct iommu with existing IOAS but new HWPT.
- create using struct iommu with new IOAS and new HWPT.

I think I should probably add following flags:

IOMMUFD_IOMMU_INIT_CREATE_IOPT (IO Page Table) or _PT
IOMMUFD_IOMMU_INIT_CREATE_IOAS (IO address Space) or _AS

At least one of those should be required when creating new struct iommu
from an existing one. WDYT?
>
>This would enable use of HWPTs in iommus constructed by iommu_init() as
>well, which someone may want to do in the future.
>
>If you go this route, please introduce this in its own commit.

Both flags can be introduced in same commit or should be separate?
>
>> +
>> +	return iommu;
>> +}
>> +
>> +static void iommufd_cleanup(struct iommu *iommu)
>> +{
>> +	struct iommu_destroy args = {
>> +		.size = sizeof(args),
>> +	};
>> +
>> +	if (iommu->hwpt_id) {
>> +		args.id = iommu->hwpt_id;
>> +		ioctl_assert(iommu->iommufd, IOMMU_DESTROY, &args);
>> +	}
>> +
>> +	args.id = iommu->ioas_id;
>> +	ioctl_assert(iommu->iommufd, IOMMU_DESTROY, &args);
>
>
>Please create a helper function to do IOMMU_DESTROY ioctl. Then here you
>can just do:
>
>  if (iommu->hwpt_id)
>          iommufd_iommu_destroy(iommu, iommu->hwpt_id);
>
>  iommfd_iommu_destroy(iommu, iommu->ioas_id);

Looks great. Will do.
>
>> +
>> +	VFIO_ASSERT_EQ(close(iommu->iommufd), 0);
>> +}
>> +
>>  void iommu_cleanup(struct iommu *iommu)
>>  {
>>  	if (iommu->iommufd)
>> -		VFIO_ASSERT_EQ(close(iommu->iommufd), 0);
>> +		iommufd_cleanup(iommu);
>>  	else
>>  		VFIO_ASSERT_EQ(close(iommu->container_fd), 0);
>>

[snip]
>> +void vfio_pci_device_attach_iommu(struct vfio_pci_device *device, struct iommu *iommu)
>> +{
>> +	u32 pt_id = iommu->ioas_id;
>> +
>> +	/* Only iommufd supports changing struct iommu attachments */
>> +	VFIO_ASSERT_TRUE(iommu->iommufd);
>> +
>> +	if (iommu->hwpt_id)
>> +		pt_id = iommu->hwpt_id;
>
>nit: This can be folded into the variable declaration.
>
>  const u32 pt_id = iommu->hwpt_id ?: iommu->ioas_id;

Agreed
>
>> +
>> +	VFIO_ASSERT_NE(pt_id, 0);
>
>Why is this check needed?

I think it is redundant. I will remove it.
>
>> +	vfio_device_attach_iommufd_pt(device->fd, pt_id);
>> +	device->iommu = iommu;
>> +}
>
>Please introduce vfio_pci_device_attach_iommu() in its own patch.

Agreed. Will do.
>
>> +
>>  static void vfio_pci_iommufd_setup(struct vfio_pci_device *device, const char *bdf)
>>  {
>>  	const char *cdev_path = vfio_pci_get_cdev_path(bdf);
>> @@ -350,8 +366,8 @@ static void vfio_pci_iommufd_setup(struct vfio_pci_device *device, const char *b
>>  	VFIO_ASSERT_GE(device->fd, 0);
>>  	free((void *)cdev_path);
>>
>> -	vfio_device_bind_iommufd(device->fd, device->iommu->iommufd);
>> -	vfio_device_attach_iommufd_pt(device->fd, device->iommu->ioas_id);
>> +	device->dev_id = vfio_device_bind_iommufd(device->fd, device->iommu->iommufd);
>> +	vfio_pci_device_attach_iommu(device, device->iommu);
>>  }
>>
>>  struct vfio_pci_device *vfio_pci_device_init(const char *bdf, struct iommu *iommu)
>> --
>> 2.54.0.545.g6539524ca2-goog
>>

Thanks,
Sami

Re: [PATCH 2/2] vfio: selftests: Add iommufd multi iommu test

[Samiullah Khawaja]

On Fri, May 08, 2026 at 08:14:08PM +0000, David Matlack wrote:
>On 2026-05-05 10:14 PM, Samiullah Khawaja wrote:
>> Add a test for iommufd to verify creation of multiple iommus using an
>> already setup iommufd and switch between them.
>>
>> Signed-off-by: Samiullah Khawaja <skhawaja@google.com>
>> ---
>>  tools/testing/selftests/vfio/Makefile         |   1 +
>>  .../vfio/vfio_iommufd_multi_iommu_test.c      | 203 ++++++++++++++++++
>>  2 files changed, 204 insertions(+)
>>  create mode 100644 tools/testing/selftests/vfio/vfio_iommufd_multi_iommu_test.c
>>
>> diff --git a/tools/testing/selftests/vfio/Makefile b/tools/testing/selftests/vfio/Makefile
>> index 0684932d91bf..24bdeaad590f 100644
>> --- a/tools/testing/selftests/vfio/Makefile
>> +++ b/tools/testing/selftests/vfio/Makefile
>> @@ -8,6 +8,7 @@ else
>>  CFLAGS = $(KHDR_INCLUDES)
>>  TEST_GEN_PROGS += vfio_dma_mapping_test
>>  TEST_GEN_PROGS += vfio_dma_mapping_mmio_test
>> +TEST_GEN_PROGS += vfio_iommufd_multi_iommu_test
>>  TEST_GEN_PROGS += vfio_iommufd_setup_test
>>  TEST_GEN_PROGS += vfio_pci_device_test
>>  TEST_GEN_PROGS += vfio_pci_device_init_perf_test
>> diff --git a/tools/testing/selftests/vfio/vfio_iommufd_multi_iommu_test.c b/tools/testing/selftests/vfio/vfio_iommufd_multi_iommu_test.c
>> new file mode 100644
>> index 000000000000..7199c662637c
>> --- /dev/null
>> +++ b/tools/testing/selftests/vfio/vfio_iommufd_multi_iommu_test.c
>> @@ -0,0 +1,203 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +#include <sys/ioctl.h>
>> +#include <sys/mman.h>
>> +
>> +#include <linux/sizes.h>
>> +#include <linux/vfio.h>
>> +
>> +#include <libvfio.h>
>> +
>> +#include "kselftest_harness.h"
>> +
>> +static const char *device_bdf;
>> +
>> +#define IOMMU_DEFAULT 0
>> +#define IOMMU_WITH_PT 1
>> +#define IOMMU_WITHOUT_PT 2
>> +
>> +static void region_setup(struct iommu *iommu,
>> +			 struct iova_allocator *iova_allocator,
>> +			 struct dma_region *region, u64 size)
>> +{
>> +	const int flags = MAP_SHARED | MAP_ANONYMOUS;
>> +	const int prot = PROT_READ | PROT_WRITE;
>> +	void *vaddr;
>> +
>> +	vaddr = mmap(NULL, size, prot, flags, -1, 0);
>> +	VFIO_ASSERT_NE(vaddr, MAP_FAILED);
>> +
>> +	region->vaddr = vaddr;
>> +	region->iova = iova_allocator_alloc(iova_allocator, size);
>> +	region->size = size;
>> +
>> +	iommu_map(iommu, region);
>> +}
>> +
>> +static void region_teardown(struct iommu *iommu, struct dma_region *region)
>> +{
>> +	iommu_unmap(iommu, region);
>> +	VFIO_ASSERT_EQ(munmap(region->vaddr, region->size), 0);
>> +}
>
>Can you create library helpers in the library to share with
>vfio_pci_driver_test.c?
>
>  dma_region_setup()
>  dma_region_teardown()

I thought it is ok to duplicate this as each test (in future) might have
different mapping requirements? we might have memfd, guest_memfd,
dma_buf with various mapping strategies for different usecases?

Or you are thinking of a basic helper that can be used by tests if they
are not doing anything fancy?
>
>> +
>> +FIXTURE(vfio_iommufd_multi_iommu_test) {
>> +	struct iommu *iommu;
>> +	struct vfio_pci_device *device;
>> +	struct iova_allocator *iova_allocator;
>> +	struct dma_region memcpy_region;
>> +	void *vaddr;
>> +
>> +	u64 size;
>> +	void *src;
>> +	void *dst;
>> +	iova_t src_iova;
>> +	iova_t dst_iova;
>> +};
>> +
>> +FIXTURE_SETUP(vfio_iommufd_multi_iommu_test)
>> +{
>> +	struct vfio_pci_driver *driver;
>> +
>> +	self->iommu = iommu_init("iommufd");
>
>MODE_IOMMUFD

Will update.
>
>> +	self->device = vfio_pci_device_init(device_bdf, self->iommu);
>> +	self->iova_allocator = iova_allocator_init(self->iommu);
>> +
>> +	driver = &self->device->driver;
>> +
>> +	region_setup(self->iommu, self->iova_allocator, &self->memcpy_region, SZ_1G);
>> +	region_setup(self->iommu, self->iova_allocator, &driver->region, SZ_2M);
>> +
>> +	if (driver->ops)
>> +		vfio_pci_driver_init(self->device);
>> +
>> +	self->size = self->memcpy_region.size / 2;
>> +	self->src = self->memcpy_region.vaddr;
>> +	self->dst = self->src + self->size;
>> +
>> +	self->src_iova = to_iova(self->device, self->src);
>> +	self->dst_iova = to_iova(self->device, self->dst);
>> +}
>> +

[snip]
>> +static void test_memcpy(struct vfio_pci_device *device, void *src, void *dst,
>> +			iova_t src_iova, iova_t dst_iova, u64 size, char val)
>> +{
>> +	if (!device->driver.ops)
>> +		return;
>> +
>> +	memset(src, val, size);
>> +	memset(dst, 0, size);
>> +
>> +	vfio_pci_driver_memcpy_start(device, src_iova, dst_iova, size, 100);
>
>Why do 100 copies?

Will remove in next revision.
>
>> +	VFIO_ASSERT_EQ(vfio_pci_driver_memcpy_wait(device), 0);
>> +	VFIO_ASSERT_EQ(memcmp(src, dst, size), 0);
>> +}
>> +
>> +TEST_F(vfio_iommufd_multi_iommu_test, memcpy)
>> +{
>> +	struct dma_region memcpy_region1, driver_region1;
>> +	struct dma_region memcpy_region2, driver_region2;
>> +	struct iommu *iommu1;
>> +	struct iommu *iommu2;
>> +
>> +	iommu1 = setup_variant_iommu(self->iommu, self->device->dev_id,
>> +				     variant->start_iommu);
>> +	if (iommu1 != self->iommu) {
>> +		memcpy_region1 = self->memcpy_region;
>> +		driver_region1 = self->device->driver.region;
>> +
>> +		iommu_map(iommu1, &memcpy_region1);
>
>Can you make a helper to copy dma_region into a new iommu? It should set
>up the new struct dma_region based on the old one, re-initialize the
>link field, and then call iommu_map().

Can you please clarify, I didn't get it completely. so basically
something that can be called like following?

setup_copy_dma_regions(self, iommu1, &memcpy_region1, &driver_region1);

I think I get that you are concerned about link init. Maybe I can do?

int clone_dma_region(struct dma_region *source_region,
                      struct dma_region *dest_region);

We can maybe add it to the library?
>
>> +		iommu_map(iommu1, &driver_region1);
>> +
>> +		vfio_pci_device_attach_iommu(self->device, iommu1);
>> +	}
>> +
>> +	test_memcpy(self->device, self->src, self->dst, self->src_iova,
>> +		    self->dst_iova, self->size, 'x');
>
>nit: You can pass in self to avoid unpacking it in every call to
>test_memcpy(). The type would be:
>
>  struct _test_data_vfio_iommufd_multi_iommu_test *self

Agreed. Will do.
>
>> +
>> +	iommu2 = setup_variant_iommu(self->iommu, self->device->dev_id,
>> +				     variant->end_iommu);
>> +	if (iommu2 != self->iommu) {
>> +		memcpy_region2 = self->memcpy_region;
>> +		driver_region2 = self->device->driver.region;
>> +
>> +		iommu_map(iommu2, &memcpy_region2);
>> +		iommu_map(iommu2, &driver_region2);
>> +	}
>> +
>> +	vfio_pci_device_attach_iommu(self->device, iommu2);
>> +	test_memcpy(self->device, self->src, self->dst, self->src_iova,
>> +		    self->dst_iova, self->size, 'a');
>
>test_memcpy() zeroes self->dst every time so do you need to use a
>different character for each call?

I will update this.
>
>> +
>> +	vfio_pci_device_attach_iommu(self->device, iommu1);
>> +	test_memcpy(self->device, self->src, self->dst, self->src_iova,
>> +		    self->dst_iova, self->size, '1');
>> +
>> +	if (iommu1 != self->iommu) {
>> +		/* attach back to default iommu for cleanup */
>> +		vfio_pci_device_attach_iommu(self->device, self->iommu);
>> +		iommu_unmap(iommu1, &memcpy_region1);
>> +		iommu_unmap(iommu1, &driver_region1);
>> +		iommu_cleanup(iommu1);
>> +	}
>> +
>> +	if (iommu2 != self->iommu) {
>> +		iommu_unmap(iommu2, &memcpy_region2);
>> +		iommu_unmap(iommu2, &driver_region2);
>
>nit: You don't need to unmap before cleanup. Is this just to exercise
>that unmap works on the variant iommus?

Not really. I thought it is needed. But I think I will keep it to
exercise that. Will add a comment to clarify.
>
>> +		iommu_cleanup(iommu2);
>> +	}
>> +}
>> +
>> +int main(int argc, char *argv[])
>> +{
>> +	device_bdf = vfio_selftests_get_bdf(&argc, argv);
>> +
>> +	return test_harness_run(argc, argv);
>> +}
>> --
>> 2.54.0.545.g6539524ca2-goog
>>

Thanks,
Sami

Re: [PATCH 1/2] vfio: selftests: Add support of creating multiple iommus from iommufd

[David Matlack]

On 2026-05-11 08:21 PM, Samiullah Khawaja wrote:
> On Fri, May 08, 2026 at 06:17:19PM +0000, David Matlack wrote:
> > On 2026-05-05 10:14 PM, Samiullah Khawaja wrote:

> > @@ -478,11 +483,7 @@ struct iommu *iommufd_iommu_init(int iommufd, u32 dev_id, u32 flags)
> >        struct iommu *iommu;
> > 
> >        iommu = iommu_alloc("iommufd");
> > -
> > -       iommu->iommufd = dup(iommufd);
> > -       VFIO_ASSERT_GT(iommu->iommufd, 0);
> > -
> > -       iommu->ioas_id = iommufd_ioas_alloc(iommu->iommufd);
> > +       iommufd_init(iommu, dup(iommufd));
> > 
> >        if (flags & IOMMUFD_IOMMU_INIT_CREATE_PT)
> >                iommu->hwpt_id = iommufd_hwpt_alloc(iommu, dev_id);
> > 
> > > +
> > > +	if (flags & IOMMUFD_IOMMU_INIT_CREATE_PT)
> > > +		iommu->hwpt_id = iommufd_hwpt_alloc(iommu, dev_id);
> > 
> > Does this need to be part of iommufd_iommu_init()? Maybe it would be
> > better to expose a separate helper to allocate a HWPT for a given struct
> > iommu *.
> 
> Hmm.. that is interesting.. I think we can have following immediate
> possibilities when creating a struct iommu (there will be more down the
> road, but can be handled in similar way):
> 
> - create using struct iommu with a new IOAS.
> - create using struct iommu with existing IOAS but new HWPT.
> - create using struct iommu with new IOAS and new HWPT.
> 
> I think I should probably add following flags:
> 
> IOMMUFD_IOMMU_INIT_CREATE_IOPT (IO Page Table) or _PT
> IOMMUFD_IOMMU_INIT_CREATE_IOAS (IO address Space) or _AS
> 
> At least one of those should be required when creating new struct iommu
> from an existing one. WDYT?

I don't love the idea of passing in flags to control the logic,
especially since not every combination of flags is valid. And also tests
would be required to pass in dev_id even if it's not needed (first
possibility in your list).

Maybe add explicit helpers for each case?

/*** static (private) helpers ***/

static u32 iommufd_hwpt_alloc(struct iommu *iommu, u32 dev_id)
{
	struct iommu_hwpt_alloc args = {
		.size = sizeof(args),
		.pt_id = iommu->ioas_id,
		.dev_id = dev_id,
	};

	VFIO_ASSERT_EQ(iommu->hwpt_id, 0);
	ioctl_assert(iommu->iommufd, IOMMU_HWPT_ALLOC, &args);

	iommu->hwpt_id = args.out_hwpt_id;
}

static struct iommu *iommufd_new(int iommufd, u32 ioas_id)
{
	struct iommu *new;

	new = iommu_alloc("iommufd");

	new->iommufd = dup(iommufd);
	VFIO_ASSERT_GT(new->iommufd, 0);

	new->ioas_id = ioas_id;

	return new;
}

/*** Public API for tests ***/

struct iommu *iommufd_new_ioas(struct iommu *cur)
{
	return iommufd_new(cur->iommufd, iommufd_ioas_alloc(cur->iommufd));
}

struct iommu *iommufd_new_hwpt(struct iommu *cur, u32 dev_id)
{
	struct iommu *new = iommufd_new(cur->iommufd, cur->ioas_id);

	iommufd_hwpt_alloc(new, dev_id);
	return new;
}

struct iommu *iommufd_new_ioas_hwpt(struct iommu *cur, u32 dev_id)
{
	struct iommu *new = iommufd_new_ioas(cur);

	iommufd_hwpt_alloc(new, dev_id);
	return new;
}

Re: [PATCH 2/2] vfio: selftests: Add iommufd multi iommu test

[David Matlack]

On 2026-05-11 08:53 PM, Samiullah Khawaja wrote:
> On Fri, May 08, 2026 at 08:14:08PM +0000, David Matlack wrote:
> > On 2026-05-05 10:14 PM, Samiullah Khawaja wrote:
> > > Add a test for iommufd to verify creation of multiple iommus using an
> > > already setup iommufd and switch between them.
> > > 
> > > Signed-off-by: Samiullah Khawaja <skhawaja@google.com>
> > > ---
> > >  tools/testing/selftests/vfio/Makefile         |   1 +
> > >  .../vfio/vfio_iommufd_multi_iommu_test.c      | 203 ++++++++++++++++++
> > >  2 files changed, 204 insertions(+)
> > >  create mode 100644 tools/testing/selftests/vfio/vfio_iommufd_multi_iommu_test.c
> > > 
> > > diff --git a/tools/testing/selftests/vfio/Makefile b/tools/testing/selftests/vfio/Makefile
> > > index 0684932d91bf..24bdeaad590f 100644
> > > --- a/tools/testing/selftests/vfio/Makefile
> > > +++ b/tools/testing/selftests/vfio/Makefile
> > > @@ -8,6 +8,7 @@ else
> > >  CFLAGS = $(KHDR_INCLUDES)
> > >  TEST_GEN_PROGS += vfio_dma_mapping_test
> > >  TEST_GEN_PROGS += vfio_dma_mapping_mmio_test
> > > +TEST_GEN_PROGS += vfio_iommufd_multi_iommu_test
> > >  TEST_GEN_PROGS += vfio_iommufd_setup_test
> > >  TEST_GEN_PROGS += vfio_pci_device_test
> > >  TEST_GEN_PROGS += vfio_pci_device_init_perf_test
> > > diff --git a/tools/testing/selftests/vfio/vfio_iommufd_multi_iommu_test.c b/tools/testing/selftests/vfio/vfio_iommufd_multi_iommu_test.c
> > > new file mode 100644
> > > index 000000000000..7199c662637c
> > > --- /dev/null
> > > +++ b/tools/testing/selftests/vfio/vfio_iommufd_multi_iommu_test.c
> > > @@ -0,0 +1,203 @@
> > > +// SPDX-License-Identifier: GPL-2.0-only
> > > +#include <sys/ioctl.h>
> > > +#include <sys/mman.h>
> > > +
> > > +#include <linux/sizes.h>
> > > +#include <linux/vfio.h>
> > > +
> > > +#include <libvfio.h>
> > > +
> > > +#include "kselftest_harness.h"
> > > +
> > > +static const char *device_bdf;
> > > +
> > > +#define IOMMU_DEFAULT 0
> > > +#define IOMMU_WITH_PT 1
> > > +#define IOMMU_WITHOUT_PT 2
> > > +
> > > +static void region_setup(struct iommu *iommu,
> > > +			 struct iova_allocator *iova_allocator,
> > > +			 struct dma_region *region, u64 size)
> > > +{
> > > +	const int flags = MAP_SHARED | MAP_ANONYMOUS;
> > > +	const int prot = PROT_READ | PROT_WRITE;
> > > +	void *vaddr;
> > > +
> > > +	vaddr = mmap(NULL, size, prot, flags, -1, 0);
> > > +	VFIO_ASSERT_NE(vaddr, MAP_FAILED);
> > > +
> > > +	region->vaddr = vaddr;
> > > +	region->iova = iova_allocator_alloc(iova_allocator, size);
> > > +	region->size = size;
> > > +
> > > +	iommu_map(iommu, region);
> > > +}
> > > +
> > > +static void region_teardown(struct iommu *iommu, struct dma_region *region)
> > > +{
> > > +	iommu_unmap(iommu, region);
> > > +	VFIO_ASSERT_EQ(munmap(region->vaddr, region->size), 0);
> > > +}
> > 
> > Can you create library helpers in the library to share with
> > vfio_pci_driver_test.c?
> > 
> >  dma_region_setup()
> >  dma_region_teardown()
> 
> I thought it is ok to duplicate this as each test (in future) might have
> different mapping requirements? we might have memfd, guest_memfd,
> dma_buf with various mapping strategies for different usecases?
> 
> Or you are thinking of a basic helper that can be used by tests if they
> are not doing anything fancy?

We have 2 tests now that need the same code to setup their regions so we
might as well share it. As new and more complex use-cases arise we can
figure out how to support them (per-test logic or fancier library
support).

> > > +TEST_F(vfio_iommufd_multi_iommu_test, memcpy)
> > > +{
> > > +	struct dma_region memcpy_region1, driver_region1;
> > > +	struct dma_region memcpy_region2, driver_region2;
> > > +	struct iommu *iommu1;
> > > +	struct iommu *iommu2;
> > > +
> > > +	iommu1 = setup_variant_iommu(self->iommu, self->device->dev_id,
> > > +				     variant->start_iommu);
> > > +	if (iommu1 != self->iommu) {
> > > +		memcpy_region1 = self->memcpy_region;
> > > +		driver_region1 = self->device->driver.region;
> > > +
> > > +		iommu_map(iommu1, &memcpy_region1);
> > 
> > Can you make a helper to copy dma_region into a new iommu? It should set
> > up the new struct dma_region based on the old one, re-initialize the
> > link field, and then call iommu_map().
> 
> Can you please clarify, I didn't get it completely. so basically
> something that can be called like following?
> 
> setup_copy_dma_regions(self, iommu1, &memcpy_region1, &driver_region1);

I was thinking something like this exposed by lib/iommu.c:

void iommu_copy_mapping(struct iommu *iommu,
			struct dma_region *new_region,
			struct dma_region *existing_region)
{
	*new_region = *existing_region;
	INIT_LIST_HEAD(&new_region->link);
	iommu_map(iommu, new_region);
}

And then in the test you just do:

if (iommu1 != self->iommu)
	iommu_copy_mapping(iommu1, memcpy_region1, self->memcpy_region);

Re: [PATCH 2/2] vfio: selftests: Add iommufd multi iommu test

[Samiullah Khawaja]

On Mon, May 11, 2026 at 09:10:42PM +0000, David Matlack wrote:
>On 2026-05-11 08:53 PM, Samiullah Khawaja wrote:
>> On Fri, May 08, 2026 at 08:14:08PM +0000, David Matlack wrote:
>> > On 2026-05-05 10:14 PM, Samiullah Khawaja wrote:
>> > > Add a test for iommufd to verify creation of multiple iommus using an
>> > > already setup iommufd and switch between them.
>> > >
>> > > Signed-off-by: Samiullah Khawaja <skhawaja@google.com>
>> > > ---
>> > >  tools/testing/selftests/vfio/Makefile         |   1 +
>> > >  .../vfio/vfio_iommufd_multi_iommu_test.c      | 203 ++++++++++++++++++
>> > >  2 files changed, 204 insertions(+)
>> > >  create mode 100644 tools/testing/selftests/vfio/vfio_iommufd_multi_iommu_test.c
>> > >
>> > > diff --git a/tools/testing/selftests/vfio/Makefile b/tools/testing/selftests/vfio/Makefile
>> > > index 0684932d91bf..24bdeaad590f 100644
>> > > --- a/tools/testing/selftests/vfio/Makefile
>> > > +++ b/tools/testing/selftests/vfio/Makefile
>> > > @@ -8,6 +8,7 @@ else
>> > >  CFLAGS = $(KHDR_INCLUDES)
>> > >  TEST_GEN_PROGS += vfio_dma_mapping_test
>> > >  TEST_GEN_PROGS += vfio_dma_mapping_mmio_test
>> > > +TEST_GEN_PROGS += vfio_iommufd_multi_iommu_test
>> > >  TEST_GEN_PROGS += vfio_iommufd_setup_test
>> > >  TEST_GEN_PROGS += vfio_pci_device_test
>> > >  TEST_GEN_PROGS += vfio_pci_device_init_perf_test
>> > > diff --git a/tools/testing/selftests/vfio/vfio_iommufd_multi_iommu_test.c b/tools/testing/selftests/vfio/vfio_iommufd_multi_iommu_test.c
>> > > new file mode 100644
>> > > index 000000000000..7199c662637c
>> > > --- /dev/null
>> > > +++ b/tools/testing/selftests/vfio/vfio_iommufd_multi_iommu_test.c
>> > > @@ -0,0 +1,203 @@
>> > > +// SPDX-License-Identifier: GPL-2.0-only
>> > > +#include <sys/ioctl.h>
>> > > +#include <sys/mman.h>
>> > > +
>> > > +#include <linux/sizes.h>
>> > > +#include <linux/vfio.h>
>> > > +
>> > > +#include <libvfio.h>
>> > > +
>> > > +#include "kselftest_harness.h"
>> > > +
>> > > +static const char *device_bdf;
>> > > +
>> > > +#define IOMMU_DEFAULT 0
>> > > +#define IOMMU_WITH_PT 1
>> > > +#define IOMMU_WITHOUT_PT 2
>> > > +
>> > > +static void region_setup(struct iommu *iommu,
>> > > +			 struct iova_allocator *iova_allocator,
>> > > +			 struct dma_region *region, u64 size)
>> > > +{
>> > > +	const int flags = MAP_SHARED | MAP_ANONYMOUS;
>> > > +	const int prot = PROT_READ | PROT_WRITE;
>> > > +	void *vaddr;
>> > > +
>> > > +	vaddr = mmap(NULL, size, prot, flags, -1, 0);
>> > > +	VFIO_ASSERT_NE(vaddr, MAP_FAILED);
>> > > +
>> > > +	region->vaddr = vaddr;
>> > > +	region->iova = iova_allocator_alloc(iova_allocator, size);
>> > > +	region->size = size;
>> > > +
>> > > +	iommu_map(iommu, region);
>> > > +}
>> > > +
>> > > +static void region_teardown(struct iommu *iommu, struct dma_region *region)
>> > > +{
>> > > +	iommu_unmap(iommu, region);
>> > > +	VFIO_ASSERT_EQ(munmap(region->vaddr, region->size), 0);
>> > > +}
>> >
>> > Can you create library helpers in the library to share with
>> > vfio_pci_driver_test.c?
>> >
>> >  dma_region_setup()
>> >  dma_region_teardown()
>>
>> I thought it is ok to duplicate this as each test (in future) might have
>> different mapping requirements? we might have memfd, guest_memfd,
>> dma_buf with various mapping strategies for different usecases?
>>
>> Or you are thinking of a basic helper that can be used by tests if they
>> are not doing anything fancy?
>
>We have 2 tests now that need the same code to setup their regions so we
>might as well share it. As new and more complex use-cases arise we can
>figure out how to support them (per-test logic or fancier library
>support).

Ok I will add this as a separate patch.
>
>> > > +TEST_F(vfio_iommufd_multi_iommu_test, memcpy)
>> > > +{
>> > > +	struct dma_region memcpy_region1, driver_region1;
>> > > +	struct dma_region memcpy_region2, driver_region2;
>> > > +	struct iommu *iommu1;
>> > > +	struct iommu *iommu2;
>> > > +
>> > > +	iommu1 = setup_variant_iommu(self->iommu, self->device->dev_id,
>> > > +				     variant->start_iommu);
>> > > +	if (iommu1 != self->iommu) {
>> > > +		memcpy_region1 = self->memcpy_region;
>> > > +		driver_region1 = self->device->driver.region;
>> > > +
>> > > +		iommu_map(iommu1, &memcpy_region1);
>> >
>> > Can you make a helper to copy dma_region into a new iommu? It should set
>> > up the new struct dma_region based on the old one, re-initialize the
>> > link field, and then call iommu_map().
>>
>> Can you please clarify, I didn't get it completely. so basically
>> something that can be called like following?
>>
>> setup_copy_dma_regions(self, iommu1, &memcpy_region1, &driver_region1);
>
>I was thinking something like this exposed by lib/iommu.c:
>
>void iommu_copy_mapping(struct iommu *iommu,
>			struct dma_region *new_region,
>			struct dma_region *existing_region)
>{
>	*new_region = *existing_region;
>	INIT_LIST_HEAD(&new_region->link);
>	iommu_map(iommu, new_region);
>}
>
>And then in the test you just do:
>
>if (iommu1 != self->iommu)
>	iommu_copy_mapping(iommu1, memcpy_region1, self->memcpy_region);

Yeah that makes sense. I will update this in next revision.

Re: [PATCH 1/2] vfio: selftests: Add support of creating multiple iommus from iommufd

[Samiullah Khawaja]

On Mon, May 11, 2026 at 08:59:53PM +0000, David Matlack wrote:
>On 2026-05-11 08:21 PM, Samiullah Khawaja wrote:
>> On Fri, May 08, 2026 at 06:17:19PM +0000, David Matlack wrote:
>> > On 2026-05-05 10:14 PM, Samiullah Khawaja wrote:
>
>> > @@ -478,11 +483,7 @@ struct iommu *iommufd_iommu_init(int iommufd, u32 dev_id, u32 flags)
>> >        struct iommu *iommu;
>> >
>> >        iommu = iommu_alloc("iommufd");
>> > -
>> > -       iommu->iommufd = dup(iommufd);
>> > -       VFIO_ASSERT_GT(iommu->iommufd, 0);
>> > -
>> > -       iommu->ioas_id = iommufd_ioas_alloc(iommu->iommufd);
>> > +       iommufd_init(iommu, dup(iommufd));
>> >
>> >        if (flags & IOMMUFD_IOMMU_INIT_CREATE_PT)
>> >                iommu->hwpt_id = iommufd_hwpt_alloc(iommu, dev_id);
>> >
>> > > +
>> > > +	if (flags & IOMMUFD_IOMMU_INIT_CREATE_PT)
>> > > +		iommu->hwpt_id = iommufd_hwpt_alloc(iommu, dev_id);
>> >
>> > Does this need to be part of iommufd_iommu_init()? Maybe it would be
>> > better to expose a separate helper to allocate a HWPT for a given struct
>> > iommu *.
>>
>> Hmm.. that is interesting.. I think we can have following immediate
>> possibilities when creating a struct iommu (there will be more down the
>> road, but can be handled in similar way):
>>
>> - create using struct iommu with a new IOAS.
>> - create using struct iommu with existing IOAS but new HWPT.
>> - create using struct iommu with new IOAS and new HWPT.
>>
>> I think I should probably add following flags:
>>
>> IOMMUFD_IOMMU_INIT_CREATE_IOPT (IO Page Table) or _PT
>> IOMMUFD_IOMMU_INIT_CREATE_IOAS (IO address Space) or _AS
>>
>> At least one of those should be required when creating new struct iommu
>> from an existing one. WDYT?
>
>I don't love the idea of passing in flags to control the logic,
>especially since not every combination of flags is valid. And also tests
>would be required to pass in dev_id even if it's not needed (first
>possibility in your list).

Agreed.
>
>Maybe add explicit helpers for each case?
>
>/*** static (private) helpers ***/
>
>static u32 iommufd_hwpt_alloc(struct iommu *iommu, u32 dev_id)
>{
>	struct iommu_hwpt_alloc args = {
>		.size = sizeof(args),
>		.pt_id = iommu->ioas_id,
>		.dev_id = dev_id,
>	};
>
>	VFIO_ASSERT_EQ(iommu->hwpt_id, 0);
>	ioctl_assert(iommu->iommufd, IOMMU_HWPT_ALLOC, &args);
>
>	iommu->hwpt_id = args.out_hwpt_id;
>}
>
>static struct iommu *iommufd_new(int iommufd, u32 ioas_id)
>{
>	struct iommu *new;
>
>	new = iommu_alloc("iommufd");
>
>	new->iommufd = dup(iommufd);
>	VFIO_ASSERT_GT(new->iommufd, 0);
>
>	new->ioas_id = ioas_id;
>
>	return new;
>}
>
>/*** Public API for tests ***/
>
>struct iommu *iommufd_new_ioas(struct iommu *cur)
>{
>	return iommufd_new(cur->iommufd, iommufd_ioas_alloc(cur->iommufd));
>}
>
>struct iommu *iommufd_new_hwpt(struct iommu *cur, u32 dev_id)
>{
>	struct iommu *new = iommufd_new(cur->iommufd, cur->ioas_id);
>
>	iommufd_hwpt_alloc(new, dev_id);
>	return new;
>}
>
>struct iommu *iommufd_new_ioas_hwpt(struct iommu *cur, u32 dev_id)
>{
>	struct iommu *new = iommufd_new_ioas(cur);
>
>	iommufd_hwpt_alloc(new, dev_id);
>	return new;
>}

This looks great. I will update in next revision.