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[34.168.149.56]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-2f91004b6a2sm13584757eec.0.2026.05.11.14.10.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 11 May 2026 14:10:46 -0700 (PDT) Date: Mon, 11 May 2026 21:10:42 +0000 From: David Matlack To: Samiullah Khawaja Cc: Aex Williamson , Shuah Khan , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH 2/2] vfio: selftests: Add iommufd multi iommu test Message-ID: References: <20260505221518.619123-1-skhawaja@google.com> <20260505221518.619123-3-skhawaja@google.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 > > > --- > > > 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 > > > +#include > > > + > > > +#include > > > +#include > > > + > > > +#include > > > + > > > +#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);