On Fri, Aug 14, 2026 at 03:29:03PM +0800, Jia Jia wrote:
VHOST_SET_FEATURES is also used to update logging while a device is
running. When ACCESS_PLATFORM stays enabled, allocating a new empty
IOTLB on every call drops valid translations and forces avoidable
misses.
Initialize the device IOTLB only when one does not already exist.
Fixes: e13a6915a03f ("vhost/vsock: add IOTLB API support")
Signed-off-by: Jia Jia <[email protected]>
---
drivers/vhost/vsock.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index b69c260eaeff..9142fa1143b2 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -869,6 +869,7 @@ static int vhost_vsock_set_features(struct vhost_vsock
*vsock, u64 features)
vsock->dev.iotlb)
vhost_clear_device_iotlb(&vsock->dev);
Ah, okay, now I see why you did it in the other patch, but if we move
dev.iotlb checks in the functions we can still do that.
- if ((features & (1ULL << VIRTIO_F_ACCESS_PLATFORM))) {
+ if ((features & (1ULL << VIRTIO_F_ACCESS_PLATFORM)) &&
+ !vsock->dev.iotlb) {
if (vhost_init_device_iotlb(&vsock->dev))
IIUC vhost_init_device_iotlb() handles the case where dev.iotlb is
already initialized and override it. Here we are preventing that.
Will we do the same in vhost-net? If yes, all the callers will call
vhost_init_device_iotlb() with `dev.iotlb` NULL, so should we remove
that behaviour and add the check we are adding here inside the
vhost_init_device_iotlb()?
Or there is an use case where vhost_init_device_iotlb() is called with
an already initialized dev.iotlb ?
Thanks,
Stefano
goto err;
--
2.34.1
