On 2020-07-07 11:46, Cornelia Huck wrote:
On Tue, 7 Jul 2020 10:44:37 +0200
Pierre Morel <pmorel@xxxxxxxxxxxxx> wrote:
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.
Hm... what about:
"If protected virtualization is active on s390, the virtio queues are
not accessible to the host, unless VIRTIO_F_IOMMU_PLATFORM has been
negotiated. Use the new arch_validate_virtio_features() interface to
enforce this."
Yes, thanks.
Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
---
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
s/arch_validate_virtio_iommu_platform/arch_validate_virtio_features/
+ * @dev: the VIRTIO device being added
+ *
+ * Return value: returns -ENODEV if any features of the
+ * device breaks the protected virtualization
+ * 0 otherwise.
I don't think you need to specify the contract here: that belongs to
the definition in the virtio core. What about simply adding a sentence
"Return an error if required features are missing on a guest running
with protected virtualization." ?
OK, right.
+ */
+int arch_validate_virtio_features(struct virtio_device *dev)
+{
Maybe jump out immediately if the guest is not protected?
+ if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
+ dev_warn(&dev->dev, "device must provide VIRTIO_F_VERSION_1\n");
+ 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");
+ return is_prot_virt_guest() ? -ENODEV : 0;
+ }
if (!is_prot_virt_guest())
return 0;
if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
dev_warn(&dev->dev,
"legacy virtio is incompatible with protected guests");
return -ENODEV;
}
if (!virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) {
dev_warn(&dev->dev,
"device does not work with limited memory access in protected guests");
return -ENODEV;
}
Yes, easier to read.
Thanks,
Pierre
--
Pierre Morel
IBM Lab Boeblingen
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