* Stefan Hajnoczi (stefa...@redhat.com) wrote:
> On Tue, Feb 09, 2021 at 07:02:06PM +0000, Dr. David Alan Gilbert (git) wrote:
> > @@ -46,6 +51,26 @@ static void vhost_user_fs_pci_realize(VirtIOPCIProxy
> > *vpci_dev, Error **errp)
> > }
> >
> > qdev_realize(vdev, BUS(&vpci_dev->bus), errp);
> > + cachesize = dev->vdev.conf.cache_size;
> > +
> > + /*
> > + * The bar starts with the data/DAX cache
> > + * Others will be added later.
> > + */
> > + memory_region_init(&dev->cachebar, OBJECT(vpci_dev),
> > + "vhost-fs-pci-cachebar", cachesize);
>
> s/vhost-fs/vhost-user-fs/ for consistency. Only worth changing if you
> respin.
Done.
> > + if (cachesize) {
> > + memory_region_add_subregion(&dev->cachebar, 0, &dev->vdev.cache);
> > + virtio_pci_add_shm_cap(vpci_dev, VIRTIO_FS_PCI_CACHE_BAR, 0,
> > cachesize,
> > + VIRTIO_FS_SHMCAP_ID_CACHE);
> > + }
> > +
> > + /* After 'realized' so the memory region exists */
> > + pci_register_bar(&vpci_dev->pci_dev, VIRTIO_FS_PCI_CACHE_BAR,
> > + PCI_BASE_ADDRESS_SPACE_MEMORY |
> > + PCI_BASE_ADDRESS_MEM_PREFETCH |
> > + PCI_BASE_ADDRESS_MEM_TYPE_64,
> > + &dev->cachebar);
>
> Please include a comment explainig why it's okay to use BAR 2, which is
> already used for the virtio-pci modern io bar (off by default):
>
> /*
> * virtio pci bar layout used by default.
> * subclasses can re-arrange things if needed.
> *
> * region 0 -- virtio legacy io bar
> * region 1 -- msi-x bar
> * region 2 -- virtio modern io bar (off by default)
> * region 4+5 -- virtio modern memory (64bit) bar
> *
> */
>
> I guess the idea is that the io bar is available since it's off by
> default. What happens if the io bar is enabled?
We don't have many choices; the only other option would be to extend
the modern memory bar at 4/5.
For now, I've added a check:
qemu-system-x86_64: -device
vhost-user-fs-pci,queue-size=1024,chardev=char0,tag=myfs,cache-size=4G,modern-pio-notify=true:
Cache can not be used together with modern_pio
> Should this bar registration should be conditional (only when cache size
> is greater than 0)?
Yes, added.
Dave
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
