Messages in this thread | | | Subject | Re: [PATCH v2 22/24] vdpa_sim: fix endian-ness of config space | From | Jason Wang <> | Date | Thu, 6 Aug 2020 11:23:45 +0800 |
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On 2020/8/5 下午8:06, Michael S. Tsirkin wrote: > On Wed, Aug 05, 2020 at 02:21:07PM +0800, Jason Wang wrote: >> On 2020/8/4 上午5:00, Michael S. Tsirkin wrote: >>> VDPA sim accesses config space as native endian - this is >>> wrong since it's a modern device and actually uses LE. >>> >>> It only supports modern guests so we could punt and >>> just force LE, but let's use the full virtio APIs since people >>> tend to copy/paste code, and this is not data path anyway. >>> >>> Signed-off-by: Michael S. Tsirkin<mst@redhat.com> >>> --- >>> drivers/vdpa/vdpa_sim/vdpa_sim.c | 31 ++++++++++++++++++++++++++----- >>> 1 file changed, 26 insertions(+), 5 deletions(-) >>> >>> diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c >>> index a9bc5e0fb353..fa05e065ff69 100644 >>> --- a/drivers/vdpa/vdpa_sim/vdpa_sim.c >>> +++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c >>> @@ -24,6 +24,7 @@ >>> #include <linux/etherdevice.h> >>> #include <linux/vringh.h> >>> #include <linux/vdpa.h> >>> +#include <linux/virtio_byteorder.h> >>> #include <linux/vhost_iotlb.h> >>> #include <uapi/linux/virtio_config.h> >>> #include <uapi/linux/virtio_net.h> >>> @@ -72,6 +73,23 @@ struct vdpasim { >>> u64 features; >>> }; >>> +/* TODO: cross-endian support */ >>> +static inline bool vdpasim_is_little_endian(struct vdpasim *vdpasim) >>> +{ >>> + return virtio_legacy_is_little_endian() || >>> + (vdpasim->features & (1ULL << VIRTIO_F_VERSION_1)); >>> +} >>> + >>> +static inline u16 vdpasim16_to_cpu(struct vdpasim *vdpasim, __virtio16 val) >>> +{ >>> + return __virtio16_to_cpu(vdpasim_is_little_endian(vdpasim), val); >>> +} >>> + >>> +static inline __virtio16 cpu_to_vdpasim16(struct vdpasim *vdpasim, u16 val) >>> +{ >>> + return __cpu_to_virtio16(vdpasim_is_little_endian(vdpasim), val); >>> +} >>> + >>> static struct vdpasim *vdpasim_dev; >>> static struct vdpasim *vdpa_to_sim(struct vdpa_device *vdpa) >>> @@ -306,7 +324,6 @@ static const struct vdpa_config_ops vdpasim_net_config_ops; >>> static struct vdpasim *vdpasim_create(void) >>> { >>> - struct virtio_net_config *config; >>> struct vdpasim *vdpasim; >>> struct device *dev; >>> int ret = -ENOMEM; >>> @@ -331,10 +348,7 @@ static struct vdpasim *vdpasim_create(void) >>> if (!vdpasim->buffer) >>> goto err_iommu; >>> - config = &vdpasim->config; >>> - config->mtu = 1500; >>> - config->status = VIRTIO_NET_S_LINK_UP; >>> - eth_random_addr(config->mac); >>> + eth_random_addr(vdpasim->config.mac); >>> vringh_set_iotlb(&vdpasim->vqs[0].vring, vdpasim->iommu); >>> vringh_set_iotlb(&vdpasim->vqs[1].vring, vdpasim->iommu); >>> @@ -448,6 +462,7 @@ static u64 vdpasim_get_features(struct vdpa_device *vdpa) >>> static int vdpasim_set_features(struct vdpa_device *vdpa, u64 features) >>> { >>> struct vdpasim *vdpasim = vdpa_to_sim(vdpa); >>> + struct virtio_net_config *config = &vdpasim->config; >>> /* DMA mapping must be done by driver */ >>> if (!(features & (1ULL << VIRTIO_F_ACCESS_PLATFORM))) >>> @@ -455,6 +470,12 @@ static int vdpasim_set_features(struct vdpa_device *vdpa, u64 features) >>> vdpasim->features = features & vdpasim_features; >>> + /* We only know whether guest is using the legacy interface here, so >>> + * that's the earliest we can set config fields. >>> + */ >> We check whether or not ACCESS_PLATFORM is set before which is probably a >> hint that only modern device is supported. So I wonder just force LE and >> fail if VERSION_1 is not set is better? >> >> Thanks > So how about I add a comment along the lines of > > /* > * vdpasim ATM requires VIRTIO_F_ACCESS_PLATFORM, so we don't need to > * support legacy guests. Keep transitional device code around for > * the benefit of people who might copy-and-paste this into transitional > * device code. > */
That's fine.
Thanks
> >
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