On 2020-07-07 13:12, Christian Borntraeger wrote:

On 07.07.20 10:44, Pierre Morel wrote:

quoted

S390, protecting the guest memory against unauthorized host access
needs to enforce VIRTIO I/O device protection through the use of
VIRTIO_F_VERSION_1 and VIRTIO_F_IOMMU_PLATFORM.

Signed-off-by: Pierre Morel <redacted>
---
  arch/s390/kernel/uv.c | 25 +++++++++++++++++++++++++
  1 file changed, 25 insertions(+)

diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
index c296e5c8dbf9..106330f6eda1 100644
--- a/arch/s390/kernel/uv.c
+++ b/arch/s390/kernel/uv.c

@@ -14,6 +14,7 @@
  #include <linux/memblock.h>
  #include <linux/pagemap.h>
  #include <linux/swap.h>
+#include <linux/virtio_config.h>
  #include <asm/facility.h>
  #include <asm/sections.h>
  #include <asm/uv.h>

@@ -413,3 +414,27 @@ static int __init uv_info_init(void)
  }
  device_initcall(uv_info_init);
  #endif
+
+/*
+ * arch_validate_virtio_iommu_platform
+ * @dev: the VIRTIO device being added
+ *
+ * Return value: returns -ENODEV if any features of the
+ *               device breaks the protected virtualization
+ *               0 otherwise.
+ */
+int arch_validate_virtio_features(struct virtio_device *dev)
+{
+	if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
+		dev_warn(&dev->dev, "device must provide VIRTIO_F_VERSION_1\n");

I think you only want to warn if is_prot_virt_guest is true? We certainly
want to be able to run as a guest of older hypervisors with virtio 0.95, no?

clear, yes.
I will first check for PV as Connie sugested.

quoted

+		return is_prot_virt_guest() ? -ENODEV : 0;
+	}
+
+	if (!virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) {
+		dev_warn(&dev->dev,
+			 "device must provide VIRTIO_F_IOMMU_PLATFORM\n");

same here.

Yes,
Thanks,

Pierre

-- 
Pierre Morel
IBM Lab Boeblingen