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vdpa: make sure set_features is invoked for legacy

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Some legacy guests just assume features are 0 after reset.
We detect that config space is accessed before features are
set and set features to 0 automatically.
Note: some legacy guests might not even access config space, if this is
reported in the field we might need to catch a kick to handle these.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Michael S. Tsirkin 2020-07-27 10:51:55 -04:00
parent 03bea764bf
commit 452639a64a
2 changed files with 35 additions and 0 deletions
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1
drivers/vdpa/vdpa.c
View File

@ -96,6 +96,7 @@ struct vdpa_device *__vdpa_alloc_device(struct device *parent,
vdev->dev.release = vdpa_release_dev;
vdev->index = err;
vdev->config = config;
vdev->features_valid = false;
err = dev_set_name(&vdev->dev, "vdpa%u", vdev->index);
if (err)

34
include/linux/vdpa.h
View File

@ -33,12 +33,14 @@ struct vdpa_notification_area {
* @dma_dev: the actual device that is performing DMA
* @config: the configuration ops for this device.
* @index: device index
* @features_valid: were features initialized? for legacy guests
*/
struct vdpa_device {
struct device dev;
struct device *dma_dev;
const struct vdpa_config_ops *config;
unsigned int index;
bool features_valid;
};
/**
@ -266,4 +268,36 @@ static inline struct device *vdpa_get_dma_dev(struct vdpa_device *vdev)
{
return vdev->dma_dev;
}
static inline void vdpa_reset(struct vdpa_device *vdev)
{
const struct vdpa_config_ops *ops = vdev->config;
vdev->features_valid = false;
ops->set_status(vdev, 0);
}
static inline int vdpa_set_features(struct vdpa_device *vdev, u64 features)
{
const struct vdpa_config_ops *ops = vdev->config;
vdev->features_valid = true;
return ops->set_features(vdev, features);
}
static inline void vdpa_get_config(struct vdpa_device *vdev, unsigned offset,
void *buf, unsigned int len)
{
const struct vdpa_config_ops *ops = vdev->config;
/*
* Config accesses aren't supposed to trigger before features are set.
* If it does happen we assume a legacy guest.
*/
if (!vdev->features_valid)
vdpa_set_features(vdev, 0);
ops->get_config(vdev, offset, buf, len);
}
#endif /* _LINUX_VDPA_H */