lkml.org 
[lkml]   [2020]   [Aug]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v2 22/24] vdpa_sim: fix endian-ness of config space
From
Date

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


>
>

\
 
 \ /
  Last update: 2020-08-06 05:24    [W:0.087 / U:0.428 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site