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([2409:4081:2c01:b2be:f39d:e902:7582:5526]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2ef2701c2f2sm3705905a91.23.2024.12.05.12.35.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Dec 2024 12:35:20 -0800 (PST) From: Sahil Siddiq X-Google-Original-From: Sahil Siddiq To: eperezma@redhat.com, sgarzare@redhat.com Cc: mst@redhat.com, qemu-devel@nongnu.org, Sahil Siddiq Subject: [RFC v4 5/5] vdpa: Support setting vring_base for packed svq Date: Fri, 6 Dec 2024 02:04:30 +0530 Message-ID: <20241205203430.76251-6-sahilcdq@proton.me> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241205203430.76251-1-sahilcdq@proton.me> References: <20241205203430.76251-1-sahilcdq@proton.me> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::1036; envelope-from=icegambit91@gmail.com; helo=mail-pj1-x1036.google.com X-Spam_score_int: -17 X-Spam_score: -1.8 X-Spam_bar: - X-Spam_report: (-1.8 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_ENVFROM_END_DIGIT=0.25, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, 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 Linux commit 1225c216d954 ("vp_vdpa: allow set vq state to initial state after reset") enabled the vp_vdpa driver to set the vq state to the device's initial state. This works differently for split and packed vqs. With shadow virtqueues enabled, vhost-vdpa sets the vring base using the VHOST_SET_VRING_BASE ioctl. The payload (vhost_vring_state) differs for split and packed vqs. The implementation in QEMU currently uses the payload required for split vqs (i.e., the num field of vhost_vring_state is set to 0). The kernel throws EOPNOTSUPP when this payload is used with packed vqs. This patch sets the num field in the payload appropriately so vhost-vdpa (with the vp_vdpa driver) can use packed svqs. Link: https://lists.nongnu.org/archive/html/qemu-devel/2024-10/msg05106.html Link: https://lore.kernel.org/r/20210602021536.39525-4-jasowang@redhat.com Link: 1225c216d954 ("vp_vdpa: allow set vq state to initial state after reset") Signed-off-by: Sahil Siddiq Acked-by: Eugenio Pérez --- Changes v3 -> v4: - New commit. - vhost-vdpa.c (vhost_vdpa_svq_setup): Add comment. hw/virtio/vhost-vdpa.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c index 97ed569792..3e32874ce9 100644 --- a/hw/virtio/vhost-vdpa.c +++ b/hw/virtio/vhost-vdpa.c @@ -1252,6 +1252,19 @@ static bool vhost_vdpa_svq_setup(struct vhost_dev *dev, }; int r; + /* In Linux, the upper 16 bits of s.num is encoded as + the last used idx while the lower 16 bits is encoded + as the last avail idx when using packed vqs. The most + significant bit for each idx represents the counter + and should be set in both cases while the remaining + bits are cleared. */ + if (virtio_vdev_has_feature(dev->vdev, VIRTIO_F_RING_PACKED)) { + uint32_t last_avail_idx = 0 | (1 << VRING_PACKED_EVENT_F_WRAP_CTR); + uint32_t last_used_idx = 0 | (1 << VRING_PACKED_EVENT_F_WRAP_CTR); + + s.num = (last_used_idx << 16) | last_avail_idx; + } + r = vhost_vdpa_set_dev_vring_base(dev, &s); if (unlikely(r)) { error_setg_errno(errp, -r, "Cannot set vring base");