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[79.13.204.15]) by smtp.gmail.com with ESMTPSA id 90sm37250897wrl.60.2020.12.15.03.43.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Dec 2020 03:43:24 -0800 (PST) Date: Tue, 15 Dec 2020 12:43:22 +0100 From: Stefano Garzarella To: Jason Wang , "Michael S. Tsirkin" Cc: Linux Virtualization , Stefan Hajnoczi , Oren Duer , Laurent Vivier , kernel list , Max Gurtovoy , Shahaf Shuler , Eli Cohen Subject: Re: [PATCH v3 13/19] vdpa_sim: add get_config callback in vdpasim_dev_attr Message-ID: References: <20201203170511.216407-1-sgarzare@redhat.com> <20201203170511.216407-14-sgarzare@redhat.com> <829a5026-a68c-6d02-49ef-f237dcae2460@redhat.com> <20201209110745.p4ybybanzip2lav3@steredhat> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20201209110745.p4ybybanzip2lav3@steredhat> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 9, 2020 at 12:07 PM Stefano Garzarella wrote: > On Mon, Dec 07, 2020 at 01:29:17PM +0800, Jason Wang wrote: > > > >On 2020/12/4 上午1:05, Stefano Garzarella wrote: > >>The get_config callback can be used by the device to fill the > >>config structure. > >>The callback will be invoked in vdpasim_get_config() before copying > >>bytes into caller buffer. > >> > >>Move vDPA-net config updates from vdpasim_set_features() in the > >>new vdpasim_net_get_config() callback. > >> > >>Signed-off-by: Stefano Garzarella > >>--- > >>v3: > >>- checked if get_config callback is set before call it > >>--- > >> drivers/vdpa/vdpa_sim/vdpa_sim.c | 35 +++++++++++++++++++------------- > >> 1 file changed, 21 insertions(+), 14 deletions(-) > >> > >>diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c > >>index fe71ed7890e1..f935ade0806b 100644 > >>--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c > >>+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c > >>@@ -60,6 +60,8 @@ struct vdpasim_virtqueue { > >> #define VDPASIM_NET_FEATURES (VDPASIM_FEATURES | \ > >> (1ULL << VIRTIO_NET_F_MAC)) > >>+struct vdpasim; > >>+ > >> struct vdpasim_dev_attr { > >> u64 supported_features; > >> size_t config_size; > >>@@ -67,6 +69,7 @@ struct vdpasim_dev_attr { > >> u32 id; > >> work_func_t work_fn; > >>+ void (*get_config)(struct vdpasim *vdpasim, void *config); > >> }; > >> /* State of each vdpasim device */ > >>@@ -522,8 +525,6 @@ static u64 vdpasim_get_features(struct vdpa_device *vdpa) > >> static int vdpasim_set_features(struct vdpa_device *vdpa, u64 features) > >> { > >> struct vdpasim *vdpasim = vdpa_to_sim(vdpa); > >>- struct virtio_net_config *config = > >>- (struct virtio_net_config *)vdpasim->config; > >> /* DMA mapping must be done by driver */ > >> if (!(features & (1ULL << VIRTIO_F_ACCESS_PLATFORM))) > >>@@ -531,16 +532,6 @@ static int vdpasim_set_features(struct vdpa_device *vdpa, u64 features) > >> vdpasim->features = features & vdpasim->dev_attr.supported_features; > >>- /* We generally only know whether guest is using the legacy interface > >>- * here, so generally that's the earliest we can set config fields. > >>- * Note: We actually require VIRTIO_F_ACCESS_PLATFORM above which > >>- * implies VIRTIO_F_VERSION_1, but let's not try to be clever here. > >>- */ > >>- > >>- config->mtu = cpu_to_vdpasim16(vdpasim, 1500); > >>- config->status = cpu_to_vdpasim16(vdpasim, VIRTIO_NET_S_LINK_UP); > >>- memcpy(config->mac, macaddr_buf, ETH_ALEN); > > > > > >Patch looks good to me. > > > >But we need Michael to confirm whether doing moving like this is safe. > >I guess what has been done were trying to make sure get_config() fail > >before set_features(), but it's not clear to me whether it's useful. > > IIUC, also looking the QEMU code, the set_features() should be called > every time before get_config(), but to be sure, in get_config(), I can > check for example if 'vdpasim->features' is not zero (we require > VIRTIO_F_ACCESS_PLATFORM set). Working on this I just realized that we already check in vdpa_get_config() that set_features() is called, so I think the moving is safe. I'll put these considerations in the commit message. Thanks, Stefano > > @Michael any suggestion? > > Thanks, > Stefano > > > > >Thanks > > > > > >>- > >> return 0; > >> } > >>@@ -595,8 +586,13 @@ static void vdpasim_get_config(struct vdpa_device *vdpa, unsigned int offset, > >> { > >> struct vdpasim *vdpasim = vdpa_to_sim(vdpa); > >>- if (offset + len < vdpasim->dev_attr.config_size) > >>- memcpy(buf, vdpasim->config + offset, len); > >>+ if (offset + len > vdpasim->dev_attr.config_size) > >>+ return; > >>+ > >>+ if (vdpasim->dev_attr.get_config) > >>+ vdpasim->dev_attr.get_config(vdpasim, vdpasim->config); > >>+ > >>+ memcpy(buf, vdpasim->config + offset, len); > >> } > >> static void vdpasim_set_config(struct vdpa_device *vdpa, unsigned int offset, > >>@@ -739,6 +735,16 @@ static const struct vdpa_config_ops vdpasim_batch_config_ops = { > >> .free = vdpasim_free, > >> }; > >>+static void vdpasim_net_get_config(struct vdpasim *vdpasim, void *config) > >>+{ > >>+ struct virtio_net_config *net_config = > >>+ (struct virtio_net_config *)config; > >>+ > >>+ net_config->mtu = cpu_to_vdpasim16(vdpasim, 1500); > >>+ net_config->status = cpu_to_vdpasim16(vdpasim, VIRTIO_NET_S_LINK_UP); > >>+ memcpy(net_config->mac, macaddr_buf, ETH_ALEN); > >>+} > >>+ > >> static int __init vdpasim_dev_init(void) > >> { > >> struct vdpasim_dev_attr dev_attr = {}; > >>@@ -747,6 +753,7 @@ static int __init vdpasim_dev_init(void) > >> dev_attr.supported_features = VDPASIM_NET_FEATURES; > >> dev_attr.nvqs = VDPASIM_VQ_NUM; > >> dev_attr.config_size = sizeof(struct virtio_net_config); > >>+ dev_attr.get_config = vdpasim_net_get_config; > >> dev_attr.work_fn = vdpasim_net_work; > >> vdpasim_dev = vdpasim_create(&dev_attr); > >