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Tsirkin" To: Andrew Stellman Cc: Jason Wang , Xuan Zhuo , Eugenio =?iso-8859-1?Q?P=E9rez?= , virtualization@lists.linux.dev Subject: Re: [PATCH 4/4] virtio_ring: preserve VIRTIO_F_RING_RESET in transport features Message-ID: <20260407122025-mutt-send-email-mst@kernel.org> References: <20260407123904.6390-1-astellman@stellman-greene.com> <20260407123904.6390-5-astellman@stellman-greene.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <20260407123904.6390-5-astellman@stellman-greene.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: zSaRyhu8sO3PfFTFGNlKX4QbdINEOeUjxUAv6XICK78_1775578918 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Tue, Apr 07, 2026 at 08:39:04AM -0400, Andrew Stellman wrote: > vring_transport_features() whitelists known transport feature bits and > clears the rest via __virtio_clear_bit(). VIRTIO_F_RING_RESET is > missing from the whitelist, so it is unconditionally cleared during > feature negotiation. Drivers that depend on ring reset capability > silently lose the feature. Hmm was this observed in practice or just from code analysis? And on which transport? Because static void vp_transport_features(struct virtio_device *vdev, u64 features) { struct virtio_pci_device *vp_dev = to_vp_device(vdev); struct pci_dev *pci_dev = vp_dev->pci_dev; if ((features & BIT_ULL(VIRTIO_F_SR_IOV)) && pci_find_ext_capability(pci_dev, PCI_EXT_CAP_ID_SRIOV)) __virtio_set_bit(vdev, VIRTIO_F_SR_IOV); if (features & BIT_ULL(VIRTIO_F_RING_RESET)) __virtio_set_bit(vdev, VIRTIO_F_RING_RESET); ... } > Add VIRTIO_F_RING_RESET to the switch statement, matching the other > transport-level features. > > Signed-off-by: Andrew Stellman > --- > drivers/virtio/virtio_ring.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index fbca7ce..2cb643f 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -3524,6 +3524,8 @@ void vring_transport_features(struct virtio_device *vdev) > break; > case VIRTIO_F_IN_ORDER: > break; > + case VIRTIO_F_RING_RESET: > + break; > default: > /* We don't understand this bit. */ > __virtio_clear_bit(vdev, i); > -- > 2.34.1