* [PATCH] vhost-user: Check vhost features for CONFIGURE_MEM_SLOTS
@ 2020-12-22 23:41 Dylan Reid
2020-12-23 5:06 ` Raphael Norwitz
0 siblings, 1 reply; 3+ messages in thread
From: Dylan Reid @ 2020-12-22 23:41 UTC (permalink / raw)
To: qemu-devel; +Cc: Dylan Reid, raphael.norwitz, mst
The `CONFIGURE_MEM_SLOTS` feature is specified by vhost, not by virtio.
Check the vhost flags for it being set.
I noticed this while testing a new vhost implementation that doesn't yet
support configuring memory slots and retested with dpdk's block example
as well.
Signed-off-by: Dylan Reid <dgreid@dylanreid.com>
---
hw/virtio/vhost-user.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 2fdd5daf74..faa0e133f2 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -1860,7 +1860,7 @@ static int vhost_user_backend_init(struct vhost_dev *dev, void *opaque)
}
/* get max memory regions if backend supports configurable RAM slots */
- if (!virtio_has_feature(dev->protocol_features,
+ if (!virtio_has_feature(features,
VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS)) {
u->user->memory_slots = VHOST_MEMORY_BASELINE_NREGIONS;
} else {
--
2.25.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] vhost-user: Check vhost features for CONFIGURE_MEM_SLOTS
2020-12-22 23:41 [PATCH] vhost-user: Check vhost features for CONFIGURE_MEM_SLOTS Dylan Reid
@ 2020-12-23 5:06 ` Raphael Norwitz
2020-12-23 20:13 ` Dylan Reid
0 siblings, 1 reply; 3+ messages in thread
From: Raphael Norwitz @ 2020-12-23 5:06 UTC (permalink / raw)
To: Dylan Reid, qemu-devel; +Cc: mst
I don't think this is right.
On Tue, Dec 22, 2020 at 03:41:26PM -0800, Dylan Reid wrote:
>
> The `CONFIGURE_MEM_SLOTS` feature is specified by vhost, not by virtio.
> Check the vhost flags for it being set.
>
Agreed - VHOST_USER_PROTCOL_F_CONFIGURE_MEM_SLOTS is negotiated at the
vhost-user, not virtio layer. The dev->protocol_features flags are taken
from the VHOST_USER_GET_PROTOCOL_FEATURES message, which retrieves the
supported vhost-user features from the backend. See libvhost-user for a
simple reference implementation.
The VHOST_USER_GET_FEATURES message retrieves the virtio protocol
features, so checking features instead of dev->protocol_features would
incorrectly check the supported virtio features instead of the vhost-user
ones.
Am I missing something here?
> I noticed this while testing a new vhost implementation that doesn't yet
> support configuring memory slots and retested with dpdk's block example
> as well.
Could you clarify what you tested with DPDK? I haven't had problems
testing other backends which do not support configuring memory slots.
>
> Signed-off-by: Dylan Reid <dgreid@dylanreid.com>
> ---
> hw/virtio/vhost-user.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index 2fdd5daf74..faa0e133f2 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -1860,7 +1860,7 @@ static int vhost_user_backend_init(struct vhost_dev *dev, void *opaque)
> }
>
> /* get max memory regions if backend supports configurable RAM slots */
> - if (!virtio_has_feature(dev->protocol_features,
> + if (!virtio_has_feature(features,
> VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS)) {
> u->user->memory_slots = VHOST_MEMORY_BASELINE_NREGIONS;
> } else {
> --
> 2.25.1
>
>
~
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] vhost-user: Check vhost features for CONFIGURE_MEM_SLOTS
2020-12-23 5:06 ` Raphael Norwitz
@ 2020-12-23 20:13 ` Dylan Reid
0 siblings, 0 replies; 3+ messages in thread
From: Dylan Reid @ 2020-12-23 20:13 UTC (permalink / raw)
To: Raphael Norwitz, qemu-devel; +Cc: mst
>Agreed - VHOST_USER_PROTCOL_F_CONFIGURE_MEM_SLOTS is negotiated at the
>vhost-user, not virtio layer. The dev->protocol_features flags are taken
>from the VHOST_USER_GET_PROTOCOL_FEATURES message, which retrieves the
>supported vhost-user features from the backend. See libvhost-user for a
>simple reference implementation.
>
>The VHOST_USER_GET_FEATURES message retrieves the virtio protocol
>features, so checking features instead of dev->protocol_features would
>incorrectly check the supported virtio features instead of the vhost-user
>ones.
>
>Am I missing something here?
No, you're not missing anything, I am(so is the code I was working with).
I hade the message number and feature bit backwards.
Thanks for taking the time to read this, your explaination got me back on the right track, I'll go fix the library I was using.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-12-23 20:14 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-12-22 23:41 [PATCH] vhost-user: Check vhost features for CONFIGURE_MEM_SLOTS Dylan Reid
2020-12-23 5:06 ` Raphael Norwitz
2020-12-23 20:13 ` Dylan Reid
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.