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Re: [PATCH v3 07/16] libqos: enforce Device Initialization order
From: |
Stefan Hajnoczi |
Subject: |
Re: [PATCH v3 07/16] libqos: enforce Device Initialization order |
Date: |
Wed, 23 Oct 2019 09:33:44 +0100 |
User-agent: |
Mutt/1.12.1 (2019-06-15) |
On Tue, Oct 22, 2019 at 08:48:31PM +0200, Thomas Huth wrote:
> On 22/10/2019 17.48, Stefan Hajnoczi wrote:
> > On Mon, Oct 21, 2019 at 02:15:53PM +0200, Thomas Huth wrote:
> >> On 19/10/2019 08.38, Stefan Hajnoczi wrote:
> >>> According to VIRTIO 1.1 "3.1.1 Driver Requirements: Device
> >>> Initialization", configuration space and virtqueues cannot be accessed
> >>> before features have been negotiated. Enforce this requirement.
> >>>
> >>> Signed-off-by: Stefan Hajnoczi <address@hidden>
> >>> ---
> >>> tests/libqos/virtio.c | 11 +++++++++++
> >>> 1 file changed, 11 insertions(+)
> >>>
> >>> diff --git a/tests/libqos/virtio.c b/tests/libqos/virtio.c
> >>> index 4f7e6bb8a1..2593996c98 100644
> >>> --- a/tests/libqos/virtio.c
> >>> +++ b/tests/libqos/virtio.c
> >>> @@ -13,23 +13,33 @@
> >>> #include "standard-headers/linux/virtio_config.h"
> >>> #include "standard-headers/linux/virtio_ring.h"
> >>>
> >>> +/* Features must be negotiated before config space or virtqueue access */
> >>> +static void check_features_negotiated(QVirtioDevice *d)
> >>> +{
> >>> + g_assert_cmphex(d->features, !=, 0);
> >>> +}
> >>
> >> Isn't it "legal" to negotiate 0 feature bits, too (for legacy devices)?
> >
> > Yes, it's possible for Legacy devices. If someone ever does that
> > they'll need to extend this code, but it's unlikely so I'd rather not
> > complicate this.
>
> Could you please add at least a comment here with that explanation?
I'll try adding a bool field in v4 so there are no problems with a 0
feature bit set.
Stefan
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- Re: [PATCH v3 04/16] virtio-scsi-test: add missing feature negotiation, (continued)
[PATCH v3 08/16] libqos: implement VIRTIO 1.0 FEATURES_OK step, Stefan Hajnoczi, 2019/10/19
[PATCH v3 09/16] libqos: access VIRTIO 1.0 vring in little-endian, Stefan Hajnoczi, 2019/10/19
[PATCH v3 10/16] libqos: add iteration support to qpci_find_capability(), Stefan Hajnoczi, 2019/10/19