From nobody Sun Feb 8 15:58:40 2026 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D028534F461; Tue, 13 Jan 2026 23:09:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=67.231.145.42 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768345766; cv=none; b=XSNKk3y+S1MhSXpmCuSttTej7NOQ5Cftr2J6ob+4hKJLSLRzoy8BJgBtOf65Zh5P5ZlrXHbq0ZgxqIrQdP6KEPeg1sv/WJ7tt6yhjki2IPhZ/vORH4qYycKFAH13UJPCNvvhUw8DHDs9w1kg5OSb3r9uR38ZLawLQwgFKtZlba4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768345766; c=relaxed/simple; bh=B9pNp3j1Dj9Gcf7HZDzPCg5yLaHt4JAmlo7rzTbtwQ4=; h=From:Date:Subject:MIME-Version:Content-Type:Message-ID:References: In-Reply-To:To:CC; b=ce9MbY5bKrJDrhdrfGSbyCiDdr00VnYu56b+CpyKG01O/lF5t4jlkhSHXO5XSJbuN303+QWQ6dBXMY3poKztBKDcULM5kwiv53E0MLYb3vs5HwPmT21QUjH9Cf1TS24Q0RkOv6ICWZPKfBkO40nWB1Kvsue+J4otfqt9+96MaNI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=fb.com; spf=pass smtp.mailfrom=meta.com; dkim=pass (2048-bit key) header.d=fb.com header.i=@fb.com header.b=WfaiFmEl; arc=none smtp.client-ip=67.231.145.42 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=fb.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=meta.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=fb.com header.i=@fb.com header.b="WfaiFmEl" Received: from pps.filterd (m0148461.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 60DN6m654099591; Tue, 13 Jan 2026 15:09:17 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=s2048-2025-q2; bh=eZHIvPhwIUYdWzpFoeqwcw1qyPbDppq6+l09hYcGKV8=; b=WfaiFmElJc/B oajvlVP8x5nP2S/sOX85dhnBnqTajPjPzvz8yJ9T66kXsJgRfLcLt5ZedQTeIZiR nUGGKjLrbF3F79/3JHKwR0C6G/VxGs7m6c9rzNvzM8/vk3uEgHSAcOX0Ei5DXCt/ U5vftRcVrRWBcIfBgQpPs50vXP3AKFb7O4F7M3zU3X7k+xAB+INoHAn1CqEMZiX8 Dj5sVGId3AappPrq5B37tbk4ulzDAIQcxtLoaZXOGc00fxgH4YayQ2qOrQaCVKA3 qtILW16cbAr4fflwG9uUa7tScaQYbAA8JxE4Te9OoJlKpFj4rs+wzuSB1WpWLNEt 21CTan8FJw== Received: from mail.thefacebook.com ([163.114.134.16]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 4bnyeh80r2-4 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT); Tue, 13 Jan 2026 15:09:17 -0800 (PST) Received: from devgpu015.cco6.facebook.com (2620:10d:c085:208::f) by mail.thefacebook.com (2620:10d:c08b:78::2ac9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.2.2562.29; Tue, 13 Jan 2026 23:09:03 +0000 From: Alex Mastro Date: Tue, 13 Jan 2026 15:08:37 -0800 Subject: [PATCH v2 2/3] vfio: selftests: Align BAR mmaps for efficient IOMMU mapping Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-ID: <20260113-map-mmio-test-v2-2-e6d34f09c0bb@fb.com> References: <20260113-map-mmio-test-v2-0-e6d34f09c0bb@fb.com> In-Reply-To: <20260113-map-mmio-test-v2-0-e6d34f09c0bb@fb.com> To: Alex Williamson , David Matlack , Shuah Khan CC: Peter Xu , , , , Jason Gunthorpe , Alex Mastro X-Mailer: b4 0.13.0 X-Proofpoint-ORIG-GUID: Xk8r-uT5EcmcNacGhrw8qbwpOAc8frUU X-Authority-Analysis: v=2.4 cv=brZBxUai c=1 sm=1 tr=0 ts=6966d09d cx=c_pps a=CB4LiSf2rd0gKozIdrpkBw==:117 a=CB4LiSf2rd0gKozIdrpkBw==:17 a=IkcTkHD0fZMA:10 a=vUbySO9Y5rIA:10 a=VkNPw1HP01LnGYTKEx00:22 a=FOH2dFAWAAAA:8 a=TV4XJVjupk0IgnZMQ3QA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMTEzMDE4NyBTYWx0ZWRfX/i/BgLaftROT Kr6NB1Qp8uCSWgPidx/OdDmqoZGhxXIUq0u3WAM7YeK4lg72WLRkWKdEs4/5YrtH+Px84y6kAWJ G8kv9mRhwW2SD0q88ruMhKbDdyy4duEO9bz2bJwW8XMp7Wiyk10JYtfWP/qRnK0nClRabU9j9Nr ObBhbsu9lStG+dviv8PbPX1Isc9HiKwCgqrdNyJm0tf/r702IbA02v4oFyiIELTau4K+3qg7ftr F7XKgOCL9N+6Cq7zFZVN26EH9whANSiIj444ZmFZWj2QDZh65R1JkbvrGCwnFnNXbq0KebsktmL 2Pb4PWIwDv1a5Ko0nyTiUJybYpfhR33sBXNMuzdpC+xeO0NkejPg4JXdFWcBTc/KhBsCX0TixQJ Mgc2u0UZUa5adG2WXmZKkUfDl0Pqu8mxp7ox7oC8vwrv9z1WuxGyFg61Cu/ECedwRLNaMRWiDZA /ncr9ApzgKSaVGNkt9A== X-Proofpoint-GUID: Xk8r-uT5EcmcNacGhrw8qbwpOAc8frUU X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2026-01-13_04,2026-01-09_02,2025-10-01_01 Update vfio_pci_bar_map() to align BAR mmaps for efficient huge page mappings. The manual mmap alignment can be removed once mmap(!MAP_FIXED) on vfio device fds improves to automatically return well-aligned addresses. Signed-off-by: Alex Mastro --- tools/testing/selftests/vfio/lib/include/libvfio.h | 9 ++++++++ tools/testing/selftests/vfio/lib/libvfio.c | 25 ++++++++++++++++++= ++++ tools/testing/selftests/vfio/lib/vfio_pci_device.c | 24 ++++++++++++++++++= ++- 3 files changed, 57 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/vfio/lib/include/libvfio.h b/tools/tes= ting/selftests/vfio/lib/include/libvfio.h index 279ddcd70194..5ebf8503586e 100644 --- a/tools/testing/selftests/vfio/lib/include/libvfio.h +++ b/tools/testing/selftests/vfio/lib/include/libvfio.h @@ -23,4 +23,13 @@ const char *vfio_selftests_get_bdf(int *argc, char *argv[]); char **vfio_selftests_get_bdfs(int *argc, char *argv[], int *nr_bdfs); =20 +/* + * Reserve virtual address space of size at an address satisfying + * (vaddr % align) =3D=3D offset. + * + * Returns the reserved vaddr. The caller is responsible for unmapping + * the returned region. + */ +void *mmap_aligned(size_t size, size_t align, size_t offset); + #endif /* SELFTESTS_VFIO_LIB_INCLUDE_LIBVFIO_H */ diff --git a/tools/testing/selftests/vfio/lib/libvfio.c b/tools/testing/sel= ftests/vfio/lib/libvfio.c index a23a3cc5be69..4529bb1e69d1 100644 --- a/tools/testing/selftests/vfio/lib/libvfio.c +++ b/tools/testing/selftests/vfio/lib/libvfio.c @@ -2,6 +2,9 @@ =20 #include #include +#include + +#include =20 #include "../../../kselftest.h" #include @@ -76,3 +79,25 @@ const char *vfio_selftests_get_bdf(int *argc, char *argv= []) =20 return vfio_selftests_get_bdfs(argc, argv, &nr_bdfs)[0]; } + +void *mmap_aligned(size_t size, size_t align, size_t offset) +{ + void *map_base, *map_align; + size_t delta; + + VFIO_ASSERT_GT(align, offset); + delta =3D align - offset; + + map_base =3D mmap(NULL, size + align, PROT_NONE, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + VFIO_ASSERT_NE(map_base, MAP_FAILED); + + map_align =3D (void *)(ALIGN((uintptr_t)map_base + delta, align) - delta); + + if (map_align > map_base) + VFIO_ASSERT_EQ(munmap(map_base, map_align - map_base), 0); + + VFIO_ASSERT_EQ(munmap(map_align + size, map_base + align - map_align), 0); + + return map_align; +} diff --git a/tools/testing/selftests/vfio/lib/vfio_pci_device.c b/tools/tes= ting/selftests/vfio/lib/vfio_pci_device.c index 13fdb4b0b10f..03f35011b5f7 100644 --- a/tools/testing/selftests/vfio/lib/vfio_pci_device.c +++ b/tools/testing/selftests/vfio/lib/vfio_pci_device.c @@ -12,10 +12,14 @@ #include =20 #include +#include #include +#include #include +#include #include #include +#include #include #include =20 @@ -124,20 +128,38 @@ static void vfio_pci_region_get(struct vfio_pci_devic= e *device, int index, static void vfio_pci_bar_map(struct vfio_pci_device *device, int index) { struct vfio_pci_bar *bar =3D &device->bars[index]; + size_t align, size; + void *vaddr; int prot =3D 0; =20 VFIO_ASSERT_LT(index, PCI_STD_NUM_BARS); VFIO_ASSERT_NULL(bar->vaddr); VFIO_ASSERT_TRUE(bar->info.flags & VFIO_REGION_INFO_FLAG_MMAP); + VFIO_ASSERT_TRUE(is_power_of_2(bar->info.size)); =20 if (bar->info.flags & VFIO_REGION_INFO_FLAG_READ) prot |=3D PROT_READ; if (bar->info.flags & VFIO_REGION_INFO_FLAG_WRITE) prot |=3D PROT_WRITE; =20 - bar->vaddr =3D mmap(NULL, bar->info.size, prot, MAP_FILE | MAP_SHARED, + size =3D bar->info.size; + + /* + * Align BAR mmaps to improve page fault granularity during potential + * subsequent IOMMU mapping of these BAR vaddr. 1G for x86 is the + * largest hugepage size across any architecture, so no benefit from + * larger alignment. BARs smaller than 1G will be aligned by their + * power-of-two size, guaranteeing sufficient alignment for smaller + * hugepages, if present. + */ + align =3D min_t(size_t, size, SZ_1G); + + vaddr =3D mmap_aligned(size, align, 0); + bar->vaddr =3D mmap(vaddr, size, prot, MAP_SHARED | MAP_FIXED, device->fd, bar->info.offset); VFIO_ASSERT_NE(bar->vaddr, MAP_FAILED); + + madvise(bar->vaddr, size, MADV_HUGEPAGE); } =20 static void vfio_pci_bar_unmap(struct vfio_pci_device *device, int index) --=20 2.47.3