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([2a01:e0a:59e:9d80:527b:9dff:feef:3874]) by smtp.gmail.com with ESMTPSA id n10sm13820055wrf.96.2022.01.31.01.22.55 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 31 Jan 2022 01:22:56 -0800 (PST) Subject: Re: [PATCH v2 3/4] virtio-iommu: Support bypass domain To: Jean-Philippe Brucker , Juan Quintela , "Dr. David Alan Gilbert" , Peter Maydell References: <20220127142940.671333-1-jean-philippe@linaro.org> <20220127142940.671333-4-jean-philippe@linaro.org> From: Eric Auger Message-ID: Date: Mon, 31 Jan 2022 10:22:54 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <20220127142940.671333-4-jean-philippe@linaro.org> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eric.auger@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US Received-SPF: pass client-ip=170.10.133.124; envelope-from=eric.auger@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 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, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, 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: , Reply-To: eric.auger@redhat.com Cc: lvivier@redhat.com, thuth@redhat.com, mst@redhat.com, cohuck@redhat.com, qemu-devel@nongnu.org, pasic@linux.ibm.com, pbonzini@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi Jean, On 1/27/22 3:29 PM, Jean-Philippe Brucker wrote: > The driver can create a bypass domain by passing the > VIRTIO_IOMMU_ATTACH_F_BYPASS flag on the ATTACH request. Bypass domains > perform slightly better than domains with identity mappings since they > skip translation. > > Signed-off-by: Jean-Philippe Brucker > --- > hw/virtio/virtio-iommu.c | 32 ++++++++++++++++++++++++++++++-- > 1 file changed, 30 insertions(+), 2 deletions(-) > > diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c > index ec02029bb6..a112428c65 100644 > --- a/hw/virtio/virtio-iommu.c > +++ b/hw/virtio/virtio-iommu.c > @@ -43,6 +43,7 @@ > > typedef struct VirtIOIOMMUDomain { > uint32_t id; > + bool bypass; I am afraid this will break the migration if you don't change vmstate_domain. See static const VMStateDescription vmstate_domain. Also you need to migrate the new bypass field. Logically we should handle this with a vmstate subsection I think to handle migration of older devices. However I doubt the device has been used in production environment supporting migration so my guess is we may skip that burden and just add the missing field. Adding Juan, Dave & Peter for advices. Thanks Eric > GTree *mappings; > QLIST_HEAD(, VirtIOIOMMUEndpoint) endpoint_list; > } VirtIOIOMMUDomain; > @@ -258,12 +259,16 @@ static void virtio_iommu_put_endpoint(gpointer data) > } > > static VirtIOIOMMUDomain *virtio_iommu_get_domain(VirtIOIOMMU *s, > - uint32_t domain_id) > + uint32_t domain_id, > + bool bypass) > { > VirtIOIOMMUDomain *domain; > > domain = g_tree_lookup(s->domains, GUINT_TO_POINTER(domain_id)); > if (domain) { > + if (domain->bypass != bypass) { > + return NULL; > + } > return domain; > } > domain = g_malloc0(sizeof(*domain)); > @@ -271,6 +276,7 @@ static VirtIOIOMMUDomain *virtio_iommu_get_domain(VirtIOIOMMU *s, > domain->mappings = g_tree_new_full((GCompareDataFunc)interval_cmp, > NULL, (GDestroyNotify)g_free, > (GDestroyNotify)g_free); > + domain->bypass = bypass; > g_tree_insert(s->domains, GUINT_TO_POINTER(domain_id), domain); > QLIST_INIT(&domain->endpoint_list); > trace_virtio_iommu_get_domain(domain_id); > @@ -334,11 +340,16 @@ static int virtio_iommu_attach(VirtIOIOMMU *s, > { > uint32_t domain_id = le32_to_cpu(req->domain); > uint32_t ep_id = le32_to_cpu(req->endpoint); > + uint32_t flags = le32_to_cpu(req->flags); > VirtIOIOMMUDomain *domain; > VirtIOIOMMUEndpoint *ep; > > trace_virtio_iommu_attach(domain_id, ep_id); > > + if (flags & ~VIRTIO_IOMMU_ATTACH_F_BYPASS) { > + return VIRTIO_IOMMU_S_INVAL; > + } > + > ep = virtio_iommu_get_endpoint(s, ep_id); > if (!ep) { > return VIRTIO_IOMMU_S_NOENT; > @@ -356,7 +367,12 @@ static int virtio_iommu_attach(VirtIOIOMMU *s, > } > } > > - domain = virtio_iommu_get_domain(s, domain_id); > + domain = virtio_iommu_get_domain(s, domain_id, > + flags & VIRTIO_IOMMU_ATTACH_F_BYPASS); > + if (!domain) { > + /* Incompatible bypass flag */ > + return VIRTIO_IOMMU_S_INVAL; > + } > QLIST_INSERT_HEAD(&domain->endpoint_list, ep, next); > > ep->domain = domain; > @@ -419,6 +435,10 @@ static int virtio_iommu_map(VirtIOIOMMU *s, > return VIRTIO_IOMMU_S_NOENT; > } > > + if (domain->bypass) { > + return VIRTIO_IOMMU_S_INVAL; > + } > + > interval = g_malloc0(sizeof(*interval)); > > interval->low = virt_start; > @@ -464,6 +484,11 @@ static int virtio_iommu_unmap(VirtIOIOMMU *s, > if (!domain) { > return VIRTIO_IOMMU_S_NOENT; > } > + > + if (domain->bypass) { > + return VIRTIO_IOMMU_S_INVAL; > + } > + > interval.low = virt_start; > interval.high = virt_end; > > @@ -780,6 +805,9 @@ static IOMMUTLBEntry virtio_iommu_translate(IOMMUMemoryRegion *mr, hwaddr addr, > entry.perm = flag; > } > goto unlock; > + } else if (ep->domain->bypass) { > + entry.perm = flag; > + goto unlock; > } > > found = g_tree_lookup_extended(ep->domain->mappings, (gpointer)(&interval),