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Tsirkin" Subject: Re: [PATCH v10 10/10] vfio: Don't issue full 2^64 unmap Message-ID: <20201030112622.0edaa660@w520.home> In-Reply-To: <20201030062513-mutt-send-email-mst@kernel.org> References: <20201008171558.410886-1-jean-philippe@linaro.org> <20201008171558.410886-11-jean-philippe@linaro.org> <20201008152214.3cb1425b@w520.home> <20201030062513-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=alex.williamson@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=alex.williamson@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/30 02:24:40 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] 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_H4=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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jean-Philippe Brucker , qemu-devel@nongnu.org, peterx@redhat.com, eric.auger@redhat.com, pbonzini@redhat.com, bbhushan2@marvell.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, 30 Oct 2020 06:25:34 -0400 "Michael S. Tsirkin" wrote: > On Thu, Oct 08, 2020 at 03:22:14PM -0600, Alex Williamson wrote: > > On Thu, 8 Oct 2020 19:15:58 +0200 > > Jean-Philippe Brucker wrote: > > > > > IOMMUs may declare memory regions spanning from 0 to UINT64_MAX. When > > > attempting to deal with such region, vfio_listener_region_del() passes a > > > size of 2^64 to int128_get64() which throws an assertion failure. Even > > > ignoring this, the VFIO_IOMMU_DMA_MAP ioctl cannot handle this size > > > since the size field is 64-bit. Split the request in two. > > > > > > Signed-off-by: Jean-Philippe Brucker > > > --- > > > For me this happens when memory_region_iommu_set_page_size_mask() > > > returns an error because a hotplugged endpoint uses an incompatible page > > > mask. vfio_connect_container() releases the memory listener which calls > > > region_del() with the 2^64 IOMMU region. There are probably other ways > > > to reach this. > > > --- > > > hw/vfio/common.c | 11 +++++++++++ > > > 1 file changed, 11 insertions(+) > > > > > > diff --git a/hw/vfio/common.c b/hw/vfio/common.c > > > index e66054b02a7..e90a89c389e 100644 > > > --- a/hw/vfio/common.c > > > +++ b/hw/vfio/common.c > > > @@ -797,6 +797,17 @@ static void vfio_listener_region_del(MemoryListener *listener, > > > } > > > > > > if (try_unmap) { > > > + if (llsize == int128_2_64()) { > > > + /* The unmap ioctl doesn't accept a full 64-bit span. */ > > > + llsize = int128_rshift(llsize, 1); > > > + ret = vfio_dma_unmap(container, iova, int128_get64(llsize)); > > > + if (ret) { > > > + error_report("vfio_dma_unmap(%p, 0x%"HWADDR_PRIx", " > > > + "0x%"HWADDR_PRIx") = %d (%m)", > > > + container, iova, int128_get64(llsize), ret); > > > + } > > > + iova += int128_get64(llsize); > > > + } > > > ret = vfio_dma_unmap(container, iova, int128_get64(llsize)); > > > if (ret) { > > > error_report("vfio_dma_unmap(%p, 0x%"HWADDR_PRIx", " > > > > We're still susceptible that splitting the range in two could result in > > unmap calls that attempt to bisect a mapping that spans both ranges. > > Both unmap calls would fail in that case. I think we could solve this > > more completely with a high water marker, but this probably good enough > > for now. > > > > Acked-by: Alex Williamson > > > Are you merging this then? > If yes > > Acked-by: Michael S. Tsirkin > No, the series is focused on virtio-iommu therefore I assumed you or Eric would merge it, thus I provided an Ack. Thanks, Alex