virtio — archive

[Michael S. Tsirkin <mgurtovoy@nvidia.com>]

On Wed, Apr 26, 2023 at 10:11:53PM +0000, Parav Pandit wrote: > > > From: Max Gurtovoy <mgurtovoy@nvidia.com> > > Sent: Wednesday, April 26, 2023 5:12 PM > > > > On 25/04/2023 1:14, Parav Pandit wrote: > > > > > > > > > On 4/24/2023 6:06 PM, Max Gurtovoy wrote: > > > > > >>> +If VIRTIO_F_ADMIN_VQ has been negotiated, and if the driver > > >>> +configures any administration virtqueues, the driver MUST configure > > >>> +the administration virtqueues using the index in the range > > >>> +\field{admin_queue_index} to \field{admin_queue_index} + > > >>> +\field{admin_queue_num} - 1 inclusive. > > >>> +The driver MAY configure less administration virtqueues than > > >>> +supported by the device. > > >> > > >> we need to say something about other virtq's indexes. > > >> For example, if aq index = 0 then for the vblk device the request > > >> queues would start from index = 1. > > >> > > >> can we address this ? > > > > > > It may slightly complicate the device implementation when device > > > dynamically changes the VQ indices based on the negotiation of the > > > feature bit. > > > Also the drivers with and without need a different VQ index handling. > > > > > > I am thinking that aq index should not overlap with the vq index in > > > range exposed by num_queues field. > > > > > > This also aligns to the exclusion of aq count from num_queues field. > > > > The namespace of the aq and other vq index is the same. > > And the configuration is done using the same queue_select and other registers. > > Thus, we need to address the above comment otherwise all the device > > virtqueues chapters are wrong. > > Michael has added below line in this patch in num_queues description so it covers the exclusion part. > > + This excludes administration virtqueues if any are supported. > > I inspected all the devices. > Following devices which has multi queue supports are fine, net, console, scsi host, gpu, input, crypto, socket, rpmb, iommu, sound, scmi, gpio. > > Following single q devices are fine too: entropy, mem ballon dev, mem, i2c, pmem. > So mostly all chapters don’t look wrong. > > Block device needs below change. > WDYT? > > From 0592d167451280bc212df7322077f4c94b28c917 Mon Sep 17 00:00:00 2001 > From: Parav Pandit <parav@nvidia.com> > Date: Thu, 27 Apr 2023 01:01:41 +0300 > Subject: [PATCH] virtio-blk: Rename num_queues to num_req_queues > > num_queues field represents number of blk specific request queues. > > Renaming it to num_req_queues reflect its precise usage. > It also avoids confusion with PCI transport's generic num_queues field. There's no confusion actually - both fields are exactly the same are they not? The one in blk just predates the one in pci. > Signed-off-by: Parav Pandit <parav@nvidia.com> > --- > device-types/blk/description.tex | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/device-types/blk/description.tex b/device-types/blk/description.tex > index f04c932..5a27399 100644 > --- a/device-types/blk/description.tex > +++ b/device-types/blk/description.tex > @@ -16,7 +16,7 @@ \subsection{Virtqueues}\label{sec:Device Types / Block Device / Virtqueues} > \end{description} > > N=1 if VIRTIO_BLK_F_MQ is not negotiated, otherwise N is set by > - \field{num_queues}. > + \field{num_req_queues}. > > \subsection{Feature bits}\label{sec:Device Types / Block Device / Feature bits} > > @@ -108,7 +108,7 @@ \subsection{Device configuration layout}\label{sec:Device Types / Block Device / > } topology; > u8 writeback; > u8 unused0; > - u16 num_queues; > + u16 num_req_queues; > le32 max_discard_sectors; > le32 max_discard_seg; > le32 discard_sector_alignment; > @@ -135,8 +135,8 @@ \subsection{Device configuration layout}\label{sec:Device Types / Block Device / > present. The availability of the others all depend on various feature > bits as indicated above. > > -The field \field{num_queues} only exists if VIRTIO_BLK_F_MQ is set. This field specifies > -the number of queues. > +The field \field{num_req_queues} only exists if VIRTIO_BLK_F_MQ is set. This field specifies > +the number of request queues. > > The parameters in the configuration space of the device \field{max_discard_sectors} > \field{discard_sector_alignment} are expressed in 512-byte units if the > -- > 2.26.2