On 2020/6/10 下午9:11, Pierre Morel wrote:
Protected Virtualisation protects the memory of the guest and
do not allow a the host to access all of its memory.

Let's refuse a VIRTIO device which does not use IOMMU
protected access.

Signed-off-by: Pierre Morel <pmo...@linux.ibm.com>
---
  drivers/s390/virtio/virtio_ccw.c | 5 +++++
  1 file changed, 5 insertions(+)

diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
index 5730572b52cd..06ffbc96587a 100644
--- a/drivers/s390/virtio/virtio_ccw.c
+++ b/drivers/s390/virtio/virtio_ccw.c
@@ -986,6 +986,11 @@ static void virtio_ccw_set_status(struct virtio_device 
*vdev, u8 status)
        if (!ccw)
                return;
+ /* Protected Virtualisation guest needs IOMMU */
+       if (is_prot_virt_guest() &&
+           !__virtio_test_bit(vdev, VIRTIO_F_IOMMU_PLATFORM))
+                       status &= ~VIRTIO_CONFIG_S_FEATURES_OK;
+
        /* Write the status to the host. */
        vcdev->dma_area->status = status;
        ccw->cmd_code = CCW_CMD_WRITE_STATUS;


I wonder whether we need move it to virtio core instead of ccw.

I think the other memory protection technologies may suffer from this as well.

Thanks

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