* [Qemu-devel] [PATCH] virtio: hide legacy features from modern guests
@ 2015-07-22 10:11 Michael S. Tsirkin
2015-07-23 8:00 ` Jason Wang
0 siblings, 1 reply; 3+ messages in thread
From: Michael S. Tsirkin @ 2015-07-22 10:11 UTC (permalink / raw)
To: qemu-devel; +Cc: Jason Wang
NOTIFY_ON_EMPTY, ANY_LAYOUT and BAD are only valid on the legacy
interface.
Hide them from modern guests.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
include/hw/virtio/virtio.h | 4 ++++
hw/virtio/virtio-pci.c | 3 ++-
2 files changed, 6 insertions(+), 1 deletion(-)
diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index fbb3c06..cbe3a5a 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -25,6 +25,10 @@
/* A guest should never accept this. It implies negotiation is broken. */
#define VIRTIO_F_BAD_FEATURE 30
+#define VIRTIO_LEGACY_FEATURES ((0x1ULL << VIRTIO_F_BAD_FEATURE) | \
+ (0x1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) | \
+ (0x1ULL << VIRTIO_F_ANY_LAYOUT))
+
struct VirtQueue;
static inline hwaddr vring_align(hwaddr addr,
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index 283401a..db8f27c 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -1095,7 +1095,8 @@ static uint64_t virtio_pci_common_read(void *opaque, hwaddr addr,
break;
case VIRTIO_PCI_COMMON_DF:
if (proxy->dfselect <= 1) {
- val = vdev->host_features >> (32 * proxy->dfselect);
+ val = (vdev->host_features & ~VIRTIO_LEGACY_FEATURES) >>
+ (32 * proxy->dfselect);
}
break;
case VIRTIO_PCI_COMMON_GFSELECT:
--
MST
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [Qemu-devel] [PATCH] virtio: hide legacy features from modern guests
2015-07-22 10:11 [Qemu-devel] [PATCH] virtio: hide legacy features from modern guests Michael S. Tsirkin
@ 2015-07-23 8:00 ` Jason Wang
2015-07-23 14:56 ` Michael S. Tsirkin
0 siblings, 1 reply; 3+ messages in thread
From: Jason Wang @ 2015-07-23 8:00 UTC (permalink / raw)
To: Michael S. Tsirkin, qemu-devel
On 07/22/2015 06:11 PM, Michael S. Tsirkin wrote:
> NOTIFY_ON_EMPTY, ANY_LAYOUT and BAD are only valid on the legacy
> interface.
>
> Hide them from modern guests.
>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Should we do the same for device specific legacy feature bits?
> ---
> include/hw/virtio/virtio.h | 4 ++++
> hw/virtio/virtio-pci.c | 3 ++-
> 2 files changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> index fbb3c06..cbe3a5a 100644
> --- a/include/hw/virtio/virtio.h
> +++ b/include/hw/virtio/virtio.h
> @@ -25,6 +25,10 @@
> /* A guest should never accept this. It implies negotiation is broken. */
> #define VIRTIO_F_BAD_FEATURE 30
>
> +#define VIRTIO_LEGACY_FEATURES ((0x1ULL << VIRTIO_F_BAD_FEATURE) | \
> + (0x1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) | \
> + (0x1ULL << VIRTIO_F_ANY_LAYOUT))
> +
> struct VirtQueue;
>
> static inline hwaddr vring_align(hwaddr addr,
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index 283401a..db8f27c 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -1095,7 +1095,8 @@ static uint64_t virtio_pci_common_read(void *opaque, hwaddr addr,
> break;
> case VIRTIO_PCI_COMMON_DF:
> if (proxy->dfselect <= 1) {
> - val = vdev->host_features >> (32 * proxy->dfselect);
> + val = (vdev->host_features & ~VIRTIO_LEGACY_FEATURES) >>
> + (32 * proxy->dfselect);
> }
> break;
> case VIRTIO_PCI_COMMON_GFSELECT:
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [Qemu-devel] [PATCH] virtio: hide legacy features from modern guests
2015-07-23 8:00 ` Jason Wang
@ 2015-07-23 14:56 ` Michael S. Tsirkin
0 siblings, 0 replies; 3+ messages in thread
From: Michael S. Tsirkin @ 2015-07-23 14:56 UTC (permalink / raw)
To: Jason Wang; +Cc: qemu-devel
On Thu, Jul 23, 2015 at 04:00:21PM +0800, Jason Wang wrote:
>
>
> On 07/22/2015 06:11 PM, Michael S. Tsirkin wrote:
> > NOTIFY_ON_EMPTY, ANY_LAYOUT and BAD are only valid on the legacy
> > interface.
> >
> > Hide them from modern guests.
> >
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
>
> Should we do the same for device specific legacy feature bits?
Depends on what do you refer to.
> > ---
> > include/hw/virtio/virtio.h | 4 ++++
> > hw/virtio/virtio-pci.c | 3 ++-
> > 2 files changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> > index fbb3c06..cbe3a5a 100644
> > --- a/include/hw/virtio/virtio.h
> > +++ b/include/hw/virtio/virtio.h
> > @@ -25,6 +25,10 @@
> > /* A guest should never accept this. It implies negotiation is broken. */
> > #define VIRTIO_F_BAD_FEATURE 30
> >
> > +#define VIRTIO_LEGACY_FEATURES ((0x1ULL << VIRTIO_F_BAD_FEATURE) | \
> > + (0x1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) | \
> > + (0x1ULL << VIRTIO_F_ANY_LAYOUT))
> > +
> > struct VirtQueue;
> >
> > static inline hwaddr vring_align(hwaddr addr,
> > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> > index 283401a..db8f27c 100644
> > --- a/hw/virtio/virtio-pci.c
> > +++ b/hw/virtio/virtio-pci.c
> > @@ -1095,7 +1095,8 @@ static uint64_t virtio_pci_common_read(void *opaque, hwaddr addr,
> > break;
> > case VIRTIO_PCI_COMMON_DF:
> > if (proxy->dfselect <= 1) {
> > - val = vdev->host_features >> (32 * proxy->dfselect);
> > + val = (vdev->host_features & ~VIRTIO_LEGACY_FEATURES) >>
> > + (32 * proxy->dfselect);
> > }
> > break;
> > case VIRTIO_PCI_COMMON_GFSELECT:
^ permalink raw reply [flat|nested] 3+ messages in thread
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2015-07-22 10:11 [Qemu-devel] [PATCH] virtio: hide legacy features from modern guests Michael S. Tsirkin
2015-07-23 8:00 ` Jason Wang
2015-07-23 14:56 ` Michael S. Tsirkin
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