Re: [PATCH RFC don't apply] vdpa_sim: endian-ness for config space
From: Jason Wang <jasowang@redhat.com>
Date: 2020-07-15 14:02:47
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On 2020/7/15 下午9:58, Michael S. Tsirkin wrote:
VDPA sim stores config space as native endian, but that is wrong: modern guests expect LE. I coded up the following to fix it up, but it is wrong too: vdpasim_create is called before guest features are known. So what should we do? New ioctl to specify the interface used? More ideas? Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Can we do the endian conversion in set_config/get_config()? Thanks
quoted hunk ↗ jump to hunk
--- drivers/vdpa/vdpa_sim/vdpa_sim.c | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-)diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c index a9bc5e0fb353..cc754ae0ec15 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)@@ -332,8 +350,8 @@ static struct vdpasim *vdpasim_create(void) goto err_iommu; config = &vdpasim->config; - config->mtu = 1500; - config->status = VIRTIO_NET_S_LINK_UP; + config->mtu = cpu_to_vdpasim16(vdpasim, 1500); + config->status = cpu_to_vdpasim16(vdpasim, VIRTIO_NET_S_LINK_UP); eth_random_addr(config->mac); vringh_set_iotlb(&vdpasim->vqs[0].vring, vdpasim->iommu);