From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f48.google.com (mail-pj1-f48.google.com [209.85.216.48]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 598623DA5B2 for ; Fri, 14 Aug 2026 20:44:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.48 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786740280; cv=none; b=IrfPtAIIlyl61f9bek+g/bUbnUdWkPfTZ1n1IaSoM78FsyKc/MTo2bytb1+Jwby8iILaKFltmVMrWEfsDvnQE9fU/S54s6mQxqIcK9samfkkVk186aI2w7VUlw2eq1o+77smEgj887dmqTWpwDcxWLxjzfXuDRqDexTM3GiZ34M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786740280; c=relaxed/simple; bh=YgJGZwopRFt5LKPovlZMJB2y70ZD41IxouMj9pWSMbA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=cpwPs/c9I4cf148KiVn3qcv54aMU+FcBMg/HJ+SK9/G5d+JSzjgfJ6xq4KFPtmVFcpTrahDT1Uwjon0COCRmCIGsZTmMas1zlWX1dWSGaWjHO8mDs3w4BggMekSJvB5jZhVUzm/+Sk7uT8n36BAkVeIPs5eLsB+eopv5nqqiP9Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=rh49zS7Y; arc=none smtp.client-ip=209.85.216.48 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="rh49zS7Y" Received: by mail-pj1-f48.google.com with SMTP id 98e67ed59e1d1-3811f512167so2083472a91.3 for ; Fri, 14 Aug 2026 13:44:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1786740279; x=1787345079; darn=vger.kernel.org; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=Q0ngp/UsrpQYsX1xt267pJp9xJ4rgNth8LSOfPppyA0=; b=rh49zS7YDRP8h/JRPHHG9zQhvQADQkmUMAMTXDNYue0Yi8yJeHbk6sz/laNot23x1u ZhPaFP7ajigxCVxWbVYB/vQmedvKXo7sXJmtsL+NuVY1VgwJPGWjyWNPRhysw6nhJvHu rr+ygDQ11Nm+kGb84bWVUzUqN2sZVwWhvvlTSxWxgUCGZqxy88Y059ZYtPQnkhm7X8DZ eC++xdv+A2G/RuxLz1mGvMDsoGEzsrIN/Fet8qJej1+aFG147IHoEfV6ugu0IfmMyjaB iikwyPfRwfmjUv3lLrUXmVsg/VQQZwzpO/doffmIrYliqO0TqcO3keMowmA3xOtAvdxu 0QSA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1786740279; x=1787345079; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=Q0ngp/UsrpQYsX1xt267pJp9xJ4rgNth8LSOfPppyA0=; b=HHDndlc/i3JN4qbyIkkHe5D5utMjNvpdGWhhnwT2PtFShoT9QW3RBIGjAgxh5TUWzA 33rucaApXkd6Z4bv/A5HzQG5GMnVGTXtRpuu4fBgR99N63SoIA6yJsmASujGXSClhWM3 CFMaSqOoOM4sEACnw1iK0F/wHy+LkOCQuJBNhQQeT+Apv5WpJHi0ku9c2+5dTn3vgX3o 8eNDGIxUAZTjv8hRszPGNH9B0fjzU38Xt2oF3cturb5Zbux2gjNSVAXqU65XeNpCEaEu kpkcq0rq3KChidmW6f9Qgk9YbPdV+WFvnn8Oj9NPqkm16icz62e/ZaktVpftfvienU+r j9rw== X-Gm-Message-State: AOJu0YxWzWMYShjP+0GR9jPto5gfO8mX8tejcq+64UKhcdo8nFesdXmg iNH0mf4nqrGa/akOQ1k5RKWGbXC0Vk4du1jwYRtpkwpOaEl76vQXkSOD9TQunAQn8Q== X-Gm-Gg: AR+sD13E6U3452JOL3A5sdvczCPJ/3qft3BFjUyeYNKBkj0stFEPTTEFFCIdGwphUPU MTivpiybxEx2XBqw4apdjPJmoOOqrMDzQtTz/0EYY/l37mFqGeR0Vj1dw4JMCLbOz137VrNf2eT YoekxA3pIzBhwSGnsf2cQ+7ckiK2joXoP8zbnkmorj4ZCrvMdmSpDbpMobhaMtaumezaN0DxW+j kihYAWB5kUfQ7ezdZerD1uIG7rn351oKeDakTQ4tOzEJZiqdvsiha+HXY0QFrQndnqtFbi0boNp YzJJkPlnJC7pNEIXuy7HbvACUvlp+nqoVn2VuonlATToc29vLEs35PJ/WmIwHQGEukhprVBYaVy gus41xDYVZX0xFnq5f6NIBR+FBd8NVUhMUAh6VjZtVTHDDnj4BfgJMaShLhbTU1hL/43lZmPLOC HZqRQFwtNtKwnWGvGr1MOLB8FZtAHWVoPT98OFOqnW9JRVukuCadeDGwnp+6tPJm5U7aa81QFIF NygkEKvryEQBIsrlJ6Ckp478i5N8A== X-Received: by 2002:a17:90b:2891:b0:381:152b:d596 with SMTP id 98e67ed59e1d1-3933b8e1ec2mr10029222a91.11.1786740278137; Fri, 14 Aug 2026 13:44:38 -0700 (PDT) Received: from google.com (132.200.185.35.bc.googleusercontent.com. [35.185.200.132]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-394ea96947dsm3950132a91.1.2026.08.14.13.44.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 14 Aug 2026 13:44:37 -0700 (PDT) Date: Fri, 14 Aug 2026 20:44:34 +0000 From: David Matlack To: Aaron Lewis Cc: kvm@vger.kernel.org, alex@shazbot.org, jgg@nvidia.com Subject: Re: [PATCH v2 3/4] vfio: selftests: Add memfd test to vfio_dma_mapping_perf_test Message-ID: References: <20260804165748.1060476-1-aaronlewis@google.com> <20260804165748.1060476-4-aaronlewis@google.com> Precedence: bulk X-Mailing-List: kvm@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: <20260804165748.1060476-4-aaronlewis@google.com> On 2026-08-04 04:57 PM, Aaron Lewis wrote: > Add a second test to "vfio_dma_mapping_perf_test" to evaluate memfd > latencies. A key motivator for adding this test is to demonstrate that > the IOMMU_IOAS_MAP_FILE ioctl is significantly faster than other methods > of mapping DMA regions. While this performance difference is not fully > apparent with the test's current capabilities, it will become evident > as more features are introduced later in the series. > > To support this, add IOMMU_IOAS_MAP_FILE ioctl support to the VFIO > selftest library via iommufd_map_file(). > > Signed-off-by: Aaron Lewis > --- > .../vfio/lib/include/libvfio/iommu.h | 7 ++ > tools/testing/selftests/vfio/lib/iommu.c | 24 +++++ > .../vfio/vfio_dma_mapping_perf_test.c | 102 ++++++++++++++++++ > 3 files changed, 133 insertions(+) > > diff --git a/tools/testing/selftests/vfio/lib/include/libvfio/iommu.h b/tools/testing/selftests/vfio/lib/include/libvfio/iommu.h > index 5c77875240f4..515976fb19be 100644 > --- a/tools/testing/selftests/vfio/lib/include/libvfio/iommu.h > +++ b/tools/testing/selftests/vfio/lib/include/libvfio/iommu.h > @@ -35,6 +35,13 @@ struct iommu { > struct iommu *iommu_init(const char *iommu_mode); > void iommu_cleanup(struct iommu *iommu); > > +int __iommufd_map_file(struct iommu *iommu, struct dma_region *region, int fd); > + > +static inline void iommufd_map_file(struct iommu *iommu, struct dma_region *region, int fd) > +{ > + VFIO_ASSERT_EQ(__iommufd_map_file(iommu, region, fd), 0); > +} > + > int __iommu_map(struct iommu *iommu, struct dma_region *region); > > static inline void iommu_map(struct iommu *iommu, struct dma_region *region) > diff --git a/tools/testing/selftests/vfio/lib/iommu.c b/tools/testing/selftests/vfio/lib/iommu.c > index b6f3c5c84e01..b76ae0a91c68 100644 > --- a/tools/testing/selftests/vfio/lib/iommu.c > +++ b/tools/testing/selftests/vfio/lib/iommu.c > @@ -97,6 +97,30 @@ iova_t iommu_hva2iova(struct iommu *iommu, void *vaddr) > return iova; > } > > +int __iommufd_map_file(struct iommu *iommu, struct dma_region *region, int fd) I would prefer to have the fd and offset (start) tracked as part of the struct dma_region. e.g. int __iommufd_map_file(struct iommu *iommu, struct dma_region *region) { ... struct iommu_ioas_map_file args = { ... .fd = region->fd, .start = region->fd_offset, ... }; > +{ > + VFIO_ASSERT_TRUE(iommu->iommufd, "IOMMU_IOAS_MAP_FILE is an IOMMUFD IOCTL."); > + > + struct iommu_ioas_map_file args = { > + .size = sizeof(args), > + .flags = IOMMU_IOAS_MAP_READABLE | > + IOMMU_IOAS_MAP_WRITEABLE | > + IOMMU_IOAS_MAP_FIXED_IOVA, > + .ioas_id = iommu->ioas_id, > + .fd = fd, > + .start = 0, > + .iova = region->iova, > + .length = region->size, > + }; > + > + if (ioctl(iommu->iommufd, IOMMU_IOAS_MAP_FILE, &args)) > + return -errno; > + > + list_add(®ion->link, &iommu->dma_regions); > + > + return 0; > +} > + > static int vfio_iommu_map(struct iommu *iommu, struct dma_region *region) > { > struct vfio_iommu_type1_dma_map args = { > diff --git a/tools/testing/selftests/vfio/vfio_dma_mapping_perf_test.c b/tools/testing/selftests/vfio/vfio_dma_mapping_perf_test.c > index 26c04cabef61..5ef85deba4ee 100644 > --- a/tools/testing/selftests/vfio/vfio_dma_mapping_perf_test.c > +++ b/tools/testing/selftests/vfio/vfio_dma_mapping_perf_test.c > @@ -83,6 +83,108 @@ TEST_F(vfio_dma_mapping_perf_test, dma_map_unmap) > TIME("munmap", ASSERT_EQ(0, munmap(region.vaddr, size))); > } > > +FIXTURE(vfio_dma_mapping_perf_memfd_test) { > + struct iommu *iommu; > + struct vfio_pci_device *device; > + struct iova_allocator *iova_allocator; > +}; > + > +FIXTURE_VARIANT(vfio_dma_mapping_perf_memfd_test) { > + const char *iommu_mode; > + int mmap_flags; > + int memfd_flags; > +}; > + > +#define FIXTURE_VARIANT_ADD_MEMFD_MODE(_name, _mmap_flags, _memfd_flags) \ > +FIXTURE_VARIANT_ADD(vfio_dma_mapping_perf_memfd_test, iommufd ## _ ## _name) {\ > + .iommu_mode = MODE_IOMMUFD, \ > + .mmap_flags = MAP_SHARED | MAP_POPULATE | (_mmap_flags), \ > + .memfd_flags = (_memfd_flags), \ > +} > + > +FIXTURE_VARIANT_ADD_MEMFD_MODE(memfd, 0, 0); > +FIXTURE_VARIANT_ADD_MEMFD_MODE(memfd_hugetlb_2mb, > + MAP_HUGETLB | MAP_HUGE_2MB, > + MFD_HUGETLB | MFD_HUGE_2MB); > +FIXTURE_VARIANT_ADD_MEMFD_MODE(memfd_hugetlb_1gb, > + MAP_HUGETLB | MAP_HUGE_1GB, > + MFD_HUGETLB | MFD_HUGE_1GB); > + > +#undef FIXTURE_VARIANT_ADD_MEMFD_MODE > + > +FIXTURE_SETUP(vfio_dma_mapping_perf_memfd_test) > +{ > + self->iommu = iommu_init(variant->iommu_mode); > + self->device = vfio_pci_device_init(device_bdf, self->iommu); > + self->iova_allocator = iova_allocator_init(self->iommu); > +} > + > +FIXTURE_TEARDOWN(vfio_dma_mapping_perf_memfd_test) > +{ > + iova_allocator_cleanup(self->iova_allocator); > + vfio_pci_device_cleanup(self->device); > + iommu_cleanup(self->iommu); > +} > + > +static void *setup_memfd(int *fd, u64 size, int mmap_flags, int mfd_flags) > +{ > + void *buf = MAP_FAILED; > + > + TIME("memfd_create", > + *fd = memfd_create("vfio_dma_mapping_perf_memfd_test", mfd_flags)); > + if (*fd < 0) > + return MAP_FAILED; > + > + if (ftruncate(*fd, size)) > + goto out; > + > + TIME("mmap", > + buf = mmap(NULL, size, PROT_READ | PROT_WRITE, mmap_flags, *fd, 0)); > + > +out: > + if (buf == MAP_FAILED) > + close(*fd); > + > + return buf; > +} > + > +static void teardown_memfd(int fd, u64 size, void *vaddr) > +{ > + if (vaddr != MAP_FAILED) > + TIME("munmap", VFIO_ASSERT_EQ(0, munmap(vaddr, size))); Checking vaddr != MAP_FAILED seems unnecessary. The test will exit if setup_memfd() fails. > + > + if (fd != -1) > + TIME("close", VFIO_ASSERT_EQ(0, close(fd))); Same here for fd != -1. > +} > + > +TEST_F(vfio_dma_mapping_perf_memfd_test, dma_map_unmap_from_file) > +{ > + const u64 size = SZ_1G; > + const int flags = variant->mmap_flags; > + struct dma_region region; > + int fd; > + > + printf("mmap size = %lluG\n", (unsigned long long)(size / SZ_1G)); > + > + region.vaddr = setup_memfd(&fd, size, variant->mmap_flags, variant->memfd_flags); > + > + /* Skip the test if there aren't enough HugeTLB pages available. */ > + if (flags & MAP_HUGETLB && region.vaddr == MAP_FAILED) > + SKIP(return, "setup_memfd() failed: %s (%d)\n", strerror(errno), errno); > + else > + ASSERT_NE(region.vaddr, MAP_FAILED); > + > + region.iova = iova_allocator_alloc(self->iova_allocator, size); > + region.size = size; > + > + TIME("IOMMU map", iommufd_map_file(self->iommu, ®ion, fd)); > + ASSERT_EQ(region.iova, to_iova(self->device, region.vaddr)); > + > + TIME("IOMMU unmap", iommu_unmap(self->iommu, ®ion)); > + > + teardown_memfd(fd, size, region.vaddr); > +} > + > int main(int argc, char *argv[]) > { > device_bdf = vfio_selftests_get_bdf(&argc, argv); > -- > 2.55.0.654.g21b8a5bc05-goog >