On Fri, Oct 23, 2020 at 01:10:06PM +0200, Greg Kurz wrote: > On Sat, 10 Oct 2020 11:30:28 +0800 > Jason Wang <jasow...@redhat.com> wrote: > > > > > On 2020/10/8 上午12:30, Greg Kurz wrote: > > > The first loop in vhost_get_log_size() computes the size of the dirty log > > > bitmap so that it allows to track changes in the entire guest memory, in > > > terms of GPA. > > > > > > When not using a vIOMMU, the address of the vring's used structure, > > > vq->used_phys, is a GPA. It is thus already covered by the first loop. > > > > > > When using a vIOMMU, vq->used_phys is a GIOVA that will be translated > > > to an HVA when the vhost backend needs to update the used structure. It > > > will log the corresponding GPAs into the bitmap but it certainly won't > > > log the GIOVA. > > > > > > So in any case, vq->used_phys shouldn't be explicitly used to size the > > > bitmap. Drop the second loop. > > > > > > This fixes a crash of the source when migrating a guest using in-kernel > > > vhost-net and iommu_platform=on on POWER, because DMA regions are put > > > over 0x800000000000000ULL. The resulting insanely huge log size causes > > > g_malloc0() to abort. > > > > > > BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1879349 > > > Signed-off-by: Greg Kurz <gr...@kaod.org> > > > --- > > > > > > This supersedes "vhost: Ignore vrings in dirty log when using a vIOMMU" > > > > > > http://patchwork.ozlabs.org/project/qemu-devel/patch/160105498386.68108.2145229309875282336.st...@bahia.lan/ > > > --- > > > hw/virtio/vhost.c | 10 ---------- > > > 1 file changed, 10 deletions(-) > > > > > > diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c > > > index 011951625442..c02b658b597f 100644 > > > --- a/hw/virtio/vhost.c > > > +++ b/hw/virtio/vhost.c > > > @@ -172,16 +172,6 @@ static uint64_t vhost_get_log_size(struct vhost_dev > > > *dev) > > > reg->memory_size); > > > log_size = MAX(log_size, last / VHOST_LOG_CHUNK + 1); > > > } > > > - for (i = 0; i < dev->nvqs; ++i) { > > > - struct vhost_virtqueue *vq = dev->vqs + i; > > > - > > > - if (!vq->used_phys && !vq->used_size) { > > > - continue; > > > - } > > > - > > > - uint64_t last = vq->used_phys + vq->used_size - 1; > > > - log_size = MAX(log_size, last / VHOST_LOG_CHUNK + 1); > > > - } > > > return log_size; > > > } > > > > > > > > > Acked-by: Jason Wang <jasow...@redhat.com> > > > > Ping ?
tagged, thanks! -- MST
