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Wed, 20 Sep 2023 13:02:09 -0700 (PDT) Received: from redhat.com ([38.15.60.12]) by smtp.gmail.com with ESMTPSA id c22-20020a02c9d6000000b0042b255d46c1sm4342563jap.11.2023.09.20.13.02.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 Sep 2023 13:02:08 -0700 (PDT) Date: Wed, 20 Sep 2023 14:02:06 -0600 From: Alex Williamson To: Eric Auger Cc: eric.auger.pro@gmail.com, qemu-devel@nongnu.org, qemu-arm@nongnu.org, clg@redhat.com, jean-philippe@linaro.org, mst@redhat.com, pbonzini@redhat.com, peter.maydell@linaro.org, peterx@redhat.com, david@redhat.com, philmd@linaro.org Subject: Re: [PATCH v2 12/12] vfio: Remove 64-bit IOVA address space assumption Message-ID: <20230920140206.6de4964c.alex.williamson@redhat.com> In-Reply-To: <20230913080423.523953-13-eric.auger@redhat.com> References: <20230913080423.523953-1-eric.auger@redhat.com> <20230913080423.523953-13-eric.auger@redhat.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.35; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=alex.williamson@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Wed, 13 Sep 2023 10:01:47 +0200 Eric Auger wrote: > Now we retrieve the usable IOVA ranges from the host, > we now the physical IOMMU aperture and we can remove > the assumption of 64b IOVA space when calling > vfio_host_win_add(). > > This works fine in general but in case of an IOMMU memory > region this becomes more tricky. For instance the virtio-iommu > MR has a 64b aperture by default. If the physical IOMMU has a > smaller aperture (typically the case for VTD), this means we > would need to resize the IOMMU MR when this latter is linked > to a container. However this happens on vfio_listener_region_add() > when calling the IOMMU MR set_iova_ranges() callback and this > would mean we would have a recursive call the > vfio_listener_region_add(). This looks like a wrong usage of > the memory API causing duplicate IOMMU MR notifier registration > for instance. > > Until we find a better solution, make sure the vfio_find_hostwin() > is not called anymore for IOMMU region. Thanks for your encouragement to double check this, it does seem like there are some gaps in the host window support. First I guess I don't understand why the last chunk here assumes a contiguous range. Shouldn't we call vfio_host_win_add() for each IOVA range? But then we have a problem that we don't necessarily get positive feedback from memory_region_iommu_set_iova_ranges(). Did the vIOMMU accept the ranges or not? Only one vIOMMU implements the callback. Should we only call memory_region_iommu_set_iova_ranges() if the range doesn't align to a host window and should the wrapper return -ENOTSUP if there is no vIOMMU support to poke holes in the range? Thanks, Alex > Signed-off-by: Eric Auger > > --- > > I have not found any working solution to the IOMMU MR resizing. > So I can remove this patch or remove the check for IOMMU MR. Maybe > this is an issue which can be handled separately? > --- > hw/vfio/common.c | 25 ++++++++++++------------- > 1 file changed, 12 insertions(+), 13 deletions(-) > > diff --git a/hw/vfio/common.c b/hw/vfio/common.c > index 26da38de05..40cac1ca91 100644 > --- a/hw/vfio/common.c > +++ b/hw/vfio/common.c > @@ -1112,13 +1112,6 @@ static void vfio_listener_region_add(MemoryListener *listener, > #endif > } > > - hostwin = vfio_find_hostwin(container, iova, end); > - if (!hostwin) { > - error_setg(&err, "Container %p can't map guest IOVA region" > - " 0x%"HWADDR_PRIx"..0x%"HWADDR_PRIx, container, iova, end); > - goto fail; > - } > - > memory_region_ref(section->mr); > > if (memory_region_is_iommu(section->mr)) { > @@ -1177,6 +1170,14 @@ static void vfio_listener_region_add(MemoryListener *listener, > return; > } > > + hostwin = vfio_find_hostwin(container, iova, end); > + if (!hostwin) { > + error_setg(&err, "Container %p can't map guest IOVA region" > + " 0x%"HWADDR_PRIx"..0x%"HWADDR_PRIx, container, iova, end); > + goto fail; > + } > + > + > /* Here we assume that memory_region_is_ram(section->mr)==true */ > > /* > @@ -2594,12 +2595,10 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as, > vfio_get_iommu_info_migration(container, info); > g_free(info); > > - /* > - * FIXME: We should parse VFIO_IOMMU_TYPE1_INFO_CAP_IOVA_RANGE > - * information to get the actual window extent rather than assume > - * a 64-bit IOVA address space. > - */ > - vfio_host_win_add(container, 0, (hwaddr)-1, container->pgsizes); > + g_assert(container->nr_iovas); > + vfio_host_win_add(container, 0, > + container->iova_ranges[container->nr_iovas - 1].end, > + container->pgsizes); > > break; > }