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bh=KTplvI6/gFdX2/UhXfHC90lA0fM8hwlb4jQEj8TJeWM=; b=AT8nIjvZXKveHMEc5+PSIzlvVD4vTbcT1asLIVBwDmK0DzFghLlQyZmtvLOhsuOoxq3vPN hjSvNutr83Np/jwlOrpOTstjjUiD9RPxfJP71twgiYKS6Q+cJ968d1hBwKCNWzFeN4K17Q mwa8p6Zo91GOvbXnkq9AyGJ0Sy7zDuA= X-MC-Unique: LJe9LkuhNzeHeTYa9gJSng-1 From: Eric Auger To: eric.auger.pro@gmail.com, eric.auger@redhat.com, qemu-devel@nongnu.org, qemu-arm@nongnu.org, mst@redhat.com, jean-philippe@linaro.org, peter.maydell@linaro.org, clg@redhat.com, yanghliu@redhat.com Cc: alex.williamson@redhat.com, zhenzhong.duan@intel.com, jasowang@redhat.com, pbonzini@redhat.com, berrange@redhat.com Subject: [PATCH v6 3/3] virtio-iommu: Change the default granule to the host page size Date: Tue, 27 Feb 2024 17:55:50 +0100 Message-ID: <20240227165730.14099-4-eric.auger@redhat.com> In-Reply-To: <20240227165730.14099-1-eric.auger@redhat.com> References: <20240227165730.14099-1-eric.auger@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.6 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.129.124; envelope-from=eric.auger@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.088, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1709053157963100004 We used to set the default granule to 4KB but with VFIO assignment it makes more sense to use the actual host page size. Indeed when hotplugging a VFIO device protected by a virtio-iommu on a 64kB/64kB host/guest config, we current get a qemu crash: "vfio: DMA mapping failed, unable to continue" This is due to the hot-attached VFIO device calling memory_region_iommu_set_page_size_mask() with 64kB granule whereas the virtio-iommu granule was already frozen to 4KB on machine init done. Set the granule property to "host" and introduce a new compat. The page size mask used before 9.0 was qemu_target_page_mask(). Since the virtio-iommu currently only supports x86_64 and aarch64, this matched a 4KB granule. Note that the new default will prevent 4kB guest on 64kB host because the granule will be set to 64kB which would be larger than the guest page size. In that situation, the virtio-iommu driver fails on viommu_domain_finalise() with "granule 0x10000 larger than system page size 0x1000". In that case the workaround is to request 4K granule. The current limitation of global granule in the virtio-iommu should be removed and turned into per domain granule. But until we get this upgraded, this new default is probably better because I don't think anyone is currently interested in running a 4KB page size guest with virtio-iommu on a 64KB host. However supporting 64kB guest on 64kB host with virtio-iommu and VFIO looks a more important feature. Signed-off-by: Eric Auger Reviewed-by: Philippe Mathieu-Daud=C3=A9 --- v4 -> v5 - use low case, mandated by the jason qapi --- hw/core/machine.c | 1 + hw/virtio/virtio-iommu.c | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/hw/core/machine.c b/hw/core/machine.c index 70ac96954c..56f38b6579 100644 --- a/hw/core/machine.c +++ b/hw/core/machine.c @@ -35,6 +35,7 @@ =20 GlobalProperty hw_compat_8_2[] =3D { { TYPE_VIRTIO_IOMMU_PCI, "aw-bits", "64" }, + { TYPE_VIRTIO_IOMMU_PCI, "granule", "4k" }, }; const size_t hw_compat_8_2_len =3D G_N_ELEMENTS(hw_compat_8_2); =20 diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c index 33e0520bc8..6831446e29 100644 --- a/hw/virtio/virtio-iommu.c +++ b/hw/virtio/virtio-iommu.c @@ -1548,7 +1548,7 @@ static Property virtio_iommu_properties[] =3D { DEFINE_PROP_BOOL("boot-bypass", VirtIOIOMMU, boot_bypass, true), DEFINE_PROP_UINT8("aw-bits", VirtIOIOMMU, aw_bits, 0), DEFINE_PROP_GRANULE_MODE("granule", VirtIOIOMMU, granule_mode, - GRANULE_MODE_4K), + GRANULE_MODE_HOST), DEFINE_PROP_END_OF_LIST(), }; =20 --=20 2.41.0