If protected virtualization is active on s390, the virtio queues are
not accessible to the host, unless VIRTIO_F_IOMMU_PLATFORM has been
negotiated.
Define CONFIG_ARCH_HAS_RESTRICTED_MEMORY_ACCESS and export
arch_has_restricted_memory_access to fail probe if that's
not the case, preventing a host error on access attempt.
Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
---
arch/s390/Kconfig | 1 +
arch/s390/mm/init.c | 30 ++++++++++++++++++++++++++++++
2 files changed, 31 insertions(+)
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 9cfd8de907cb..d4a3ef4fa27b 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -820,6 +820,7 @@ menu "Virtualization"
config PROTECTED_VIRTUALIZATION_GUEST
def_bool n
prompt "Protected virtualization guest support"
+ select ARCH_HAS_RESTRICTED_MEMORY_ACCESS
help
Select this option, if you want to be able to run this
kernel as a protected virtualization KVM guest.
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index 6dc7c3b60ef6..aec04d7dd089 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -45,6 +45,7 @@
#include <asm/kasan.h>
#include <asm/dma-mapping.h>
#include <asm/uv.h>
+#include <linux/virtio_config.h>
pgd_t swapper_pg_dir[PTRS_PER_PGD] __section(.bss..swapper_pg_dir);
@@ -161,6 +162,35 @@ bool force_dma_unencrypted(struct device *dev)
return is_prot_virt_guest();
}
+#ifdef CONFIG_ARCH_HAS_RESTRICTED_MEMORY_ACCESS
+/*
+ * arch_has_restricted_memory_access
+ * @dev: the VIRTIO device being added
+ *
+ * Return an error if required features are missing on a guest running
+ * with protected virtualization.
+ */
+int arch_has_restricted_memory_access(struct virtio_device *dev)
+{
+ if (!is_prot_virt_guest())
+ return 0;
+
+ if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
+ dev_warn(&dev->dev, "device must provide VIRTIO_F_VERSION_1\n");
+ return -ENODEV;
+ }
+
+ if (!virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) {
+ dev_warn(&dev->dev,
+ "device must provide VIRTIO_F_IOMMU_PLATFORM\n");
+ return -ENODEV;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL(arch_has_restricted_memory_access);
+#endif
+
/* protected virtualization */
static void pv_init(void)
{
--
2.25.1
