| Message ID | 20191213095410.1516119-1-jean-philippe@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | virtio-mmio: Clear v2 transport state on soft reset | expand |
Jean-Philippe Brucker <jean-philippe@linaro.org> writes: > At the moment when the guest writes a status of 0, we only reset the > virtio core state but not the virtio-mmio state. The virtio-mmio > specification says (v1.1 cs01, 4.2.2.1 Device Requirements: > MMIO Device Register Layout): > > Upon reset, the device MUST clear all bits in InterruptStatus and > ready bits in the QueueReady register for all queues in the device. > > The core already takes care of InterruptStatus by clearing isr, but we > still need to clear QueueReady. > > It would be tempting to clean all registers, but since the specification > doesn't say anything more, guests could rely on the registers keeping > their state across reset. Linux for example, relies on this for > GuestPageSize in the legacy MMIO tranport. > > Fixes: 44e687a4d9ab ("virtio-mmio: implement modern (v2) personality (virtio-1)") > Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org> > --- > This fixes kexec of a Linux guest that uses the modern virtio-mmio > transport. > --- > hw/virtio/virtio-mmio.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) LGTM, thanks! Reviewed-by: Sergio Lopez <slp@redhat.com>
diff --git a/hw/virtio/virtio-mmio.c b/hw/virtio/virtio-mmio.c index 94d934c44b..ef40b7a9b2 100644 --- a/hw/virtio/virtio-mmio.c +++ b/hw/virtio/virtio-mmio.c @@ -65,6 +65,19 @@ static void virtio_mmio_stop_ioeventfd(VirtIOMMIOProxy *proxy) virtio_bus_stop_ioeventfd(&proxy->bus); } +static void virtio_mmio_soft_reset(VirtIOMMIOProxy *proxy) +{ + int i; + + if (proxy->legacy) { + return; + } + + for (i = 0; i < VIRTIO_QUEUE_MAX; i++) { + proxy->vqs[i].enabled = 0; + } +} + static uint64_t virtio_mmio_read(void *opaque, hwaddr offset, unsigned size) { VirtIOMMIOProxy *proxy = (VirtIOMMIOProxy *)opaque; @@ -378,6 +391,7 @@ static void virtio_mmio_write(void *opaque, hwaddr offset, uint64_t value, if (vdev->status == 0) { virtio_reset(vdev); + virtio_mmio_soft_reset(proxy); } break; case VIRTIO_MMIO_QUEUE_DESC_LOW:
At the moment when the guest writes a status of 0, we only reset the virtio core state but not the virtio-mmio state. The virtio-mmio specification says (v1.1 cs01, 4.2.2.1 Device Requirements: MMIO Device Register Layout): Upon reset, the device MUST clear all bits in InterruptStatus and ready bits in the QueueReady register for all queues in the device. The core already takes care of InterruptStatus by clearing isr, but we still need to clear QueueReady. It would be tempting to clean all registers, but since the specification doesn't say anything more, guests could rely on the registers keeping their state across reset. Linux for example, relies on this for GuestPageSize in the legacy MMIO tranport. Fixes: 44e687a4d9ab ("virtio-mmio: implement modern (v2) personality (virtio-1)") Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org> --- This fixes kexec of a Linux guest that uses the modern virtio-mmio transport. --- hw/virtio/virtio-mmio.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)