VIRTIO_BALLOON_F_MUST_TELL_HOST cannot be used properly because it is a "negative" feature: it tells you that silent defalte is not supported. Right now, QEMU refuses migration if the target does not support all the features that were negotiated. But then: - a migration from non-MUST_TELL_HOST to MUST_TELL_HOST will succeed, which is wrong; - a migration from MUST_TELL_HOST to non-MUST_TELL_HOST will fail, which is useless. Add instead a new feature VIRTIO_BALLOON_F_SILENT_DEFLATE, and deprecate VIRTIO_BALLOON_F_MUST_TELL_HOST since it is never actually used. Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> --- virtio-spec.lyx | 36 +++++++++++++++++++++++++++++++++--- 1 file modificato, 33 inserzioni(+), 3 rimozioni(-) diff --git a/virtio-spec.lyx b/virtio-spec.lyx index 7a073f4..1a25a18 100644 --- a/virtio-spec.lyx +++ b/virtio-spec.lyx @@ -6238,6 +6238,8 @@ bits \begin_deeper \begin_layout Description + +\change_deleted 1531152142 1346917221 VIRTIO_BALLOON_F_MUST_TELL_HOST \begin_inset space ~ \end_inset @@ -6251,6 +6253,20 @@ VIRTIO_BALLOON_F_STATS_VQ \end_inset (1) A virtqueue for reporting guest memory statistics is present. +\change_inserted 1531152142 1346917193 + +\end_layout + +\begin_layout Description + +\change_inserted 1531152142 1346917219 +VIRTIO_BALLOON_F_SILENT_DEFLATE +\begin_inset space ~ +\end_inset + +(2) Host does not need to be told before pages from the balloon are used. +\change_unchanged + \end_layout \end_deeper @@ -6401,9 +6417,23 @@ The driver constructs an array of addresses of memory pages it has previously \end_layout \begin_layout Enumerate -If the VIRTIO_BALLOON_F_MUST_TELL_HOST feature is set, the guest may not - use these requested pages until that descriptor in the deflateq has been - used by the device. +If the VIRTIO_BALLOON_F_ +\change_deleted 1531152142 1346917234 +MUST_TELL_HOST +\change_inserted 1531152142 1346917237 +SILENT_DEFLATE +\change_unchanged + feature is +\change_inserted 1531152142 1346917241 +not +\change_unchanged +set, the guest may not use these requested pages until that descriptor in + the deflateq has been used by the device. + +\change_inserted 1531152142 1346917253 + If it is set, the guest may choose to not use the deflateq at all. +\change_unchanged + \end_layout \begin_layout Enumerate -- 1.7.11.2 _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
