Re: [RFC PATCH v2 0/5] virtio: early detect 'modern' virtio
On Thu, Dec 09, 2021 at 02:29:25PM +0100, Halil Pasic wrote: > On Wed, 8 Dec 2021 13:56:19 -0500 > "Michael S. Tsirkin" wrote: > > > On Fri, Nov 12, 2021 at 03:57:44PM +0100, Halil Pasic wrote: > > > This is an early RFC for a transport specific early detecton of > > > modern virtio, which is most relevant for transitional devices on big > > > endian platforms, when drivers access the config space before > > > FEATURES_OK is set. > > > > > > The most important part that is missing here is fixing all the problems > > > that arise in the situation described in the previous paragraph, when > > > the config is managed by a vhost device (and thus outside QEMU. This > > > series tackles this problem only for virtio_net+vhost as an example. If > > > this approach is deemed good, we need to do something very similar for > > > every single affected device. > > > > > > This series was only lightly tested. The vhost stuff is entirely > > > untested, unfortunately I don't have a working setup where this > > > handling would be needed (because the config space is handled in the > > > device). DPDK is not supported on s390x so at the moment I can't test > > > DPDK based setups. > > > > So this looks sane to me. Cornelia requested some name tweaks and we > > need to add vhost-user things and more devices, but otherwise we are > > good. > > Thanks for your feedback! There were several points where I could > not reach agreement with Cornelia. From your response I recon that: > > 1) I should rename virtio_force_modern() to virtio_indicate_modern() > (per maintainer request). > 2) Keep the call to virtio_set_features()? > > Is that right? > > Regards, > Halil that's my take, yes. -- MST
Re: [RFC PATCH v2 0/5] virtio: early detect 'modern' virtio
On Wed, 8 Dec 2021 13:56:19 -0500 "Michael S. Tsirkin" wrote: > On Fri, Nov 12, 2021 at 03:57:44PM +0100, Halil Pasic wrote: > > This is an early RFC for a transport specific early detecton of > > modern virtio, which is most relevant for transitional devices on big > > endian platforms, when drivers access the config space before > > FEATURES_OK is set. > > > > The most important part that is missing here is fixing all the problems > > that arise in the situation described in the previous paragraph, when > > the config is managed by a vhost device (and thus outside QEMU. This > > series tackles this problem only for virtio_net+vhost as an example. If > > this approach is deemed good, we need to do something very similar for > > every single affected device. > > > > This series was only lightly tested. The vhost stuff is entirely > > untested, unfortunately I don't have a working setup where this > > handling would be needed (because the config space is handled in the > > device). DPDK is not supported on s390x so at the moment I can't test > > DPDK based setups. > > So this looks sane to me. Cornelia requested some name tweaks and we > need to add vhost-user things and more devices, but otherwise we are > good. Thanks for your feedback! There were several points where I could not reach agreement with Cornelia. From your response I recon that: 1) I should rename virtio_force_modern() to virtio_indicate_modern() (per maintainer request). 2) Keep the call to virtio_set_features()? Is that right? Regards, Halil
Re: [RFC PATCH v2 0/5] virtio: early detect 'modern' virtio
On Fri, Nov 12, 2021 at 03:57:44PM +0100, Halil Pasic wrote: > This is an early RFC for a transport specific early detecton of > modern virtio, which is most relevant for transitional devices on big > endian platforms, when drivers access the config space before > FEATURES_OK is set. > > The most important part that is missing here is fixing all the problems > that arise in the situation described in the previous paragraph, when > the config is managed by a vhost device (and thus outside QEMU. This > series tackles this problem only for virtio_net+vhost as an example. If > this approach is deemed good, we need to do something very similar for > every single affected device. > > This series was only lightly tested. The vhost stuff is entirely > untested, unfortunately I don't have a working setup where this > handling would be needed (because the config space is handled in the > device). DPDK is not supported on s390x so at the moment I can't test > DPDK based setups. So this looks sane to me. Cornelia requested some name tweaks and we need to add vhost-user things and more devices, but otherwise we are good. > v1 -> v2: > > * add callback > * tweak feature manipulation > * add generic handling for vhost that needs to be called by devices > * add handling for virtio > > Halil Pasic (5): > virtio: introduce virtio_force_modern() > virtio-ccw: use virtio_force_modern() > virtio-pci: use virtio_force_modern() > vhost: push features to backend on force_modern > virtio-net: handle force_modern for vhost > > hw/net/virtio-net.c| 20 > hw/s390x/virtio-ccw.c | 3 +++ > hw/virtio/vhost.c | 17 + > hw/virtio/virtio-pci.c | 1 + > hw/virtio/virtio.c | 13 + > include/hw/virtio/vhost.h | 2 ++ > include/hw/virtio/virtio.h | 2 ++ > 7 files changed, 58 insertions(+) > > > base-commit: 2c3e83f92d93fbab071b8a96b8ab769b01902475 > -- > 2.25.1
Re: [RFC PATCH v2 0/5] virtio: early detect 'modern' virtio
On Tue, 23 Nov 2021 14:13:40 +0100 Halil Pasic wrote: > On Fri, 12 Nov 2021 15:57:44 +0100 > Halil Pasic wrote: > > > This is an early RFC for a transport specific early detecton of > > modern virtio, which is most relevant for transitional devices on big > > endian platforms, when drivers access the config space before > > FEATURES_OK is set. > > [..] > > Ping! > > @Michael: Can you have a look at this, please? Ping^2
Re: [RFC PATCH v2 0/5] virtio: early detect 'modern' virtio
On Fri, 12 Nov 2021 15:57:44 +0100 Halil Pasic wrote: > This is an early RFC for a transport specific early detecton of > modern virtio, which is most relevant for transitional devices on big > endian platforms, when drivers access the config space before > FEATURES_OK is set. [..] Ping! @Michael: Can you have a look at this, please?
[RFC PATCH v2 0/5] virtio: early detect 'modern' virtio
This is an early RFC for a transport specific early detecton of modern virtio, which is most relevant for transitional devices on big endian platforms, when drivers access the config space before FEATURES_OK is set. The most important part that is missing here is fixing all the problems that arise in the situation described in the previous paragraph, when the config is managed by a vhost device (and thus outside QEMU. This series tackles this problem only for virtio_net+vhost as an example. If this approach is deemed good, we need to do something very similar for every single affected device. This series was only lightly tested. The vhost stuff is entirely untested, unfortunately I don't have a working setup where this handling would be needed (because the config space is handled in the device). DPDK is not supported on s390x so at the moment I can't test DPDK based setups. v1 -> v2: * add callback * tweak feature manipulation * add generic handling for vhost that needs to be called by devices * add handling for virtio Halil Pasic (5): virtio: introduce virtio_force_modern() virtio-ccw: use virtio_force_modern() virtio-pci: use virtio_force_modern() vhost: push features to backend on force_modern virtio-net: handle force_modern for vhost hw/net/virtio-net.c| 20 hw/s390x/virtio-ccw.c | 3 +++ hw/virtio/vhost.c | 17 + hw/virtio/virtio-pci.c | 1 + hw/virtio/virtio.c | 13 + include/hw/virtio/vhost.h | 2 ++ include/hw/virtio/virtio.h | 2 ++ 7 files changed, 58 insertions(+) base-commit: 2c3e83f92d93fbab071b8a96b8ab769b01902475 -- 2.25.1
