[PATCH v10 2/2] s390: virtio: PV needs VIRTIO I/O device protection

[Pierre Morel]

If protected virtualization is active on s390, VIRTIO has only retricted
access to the guest memory.
Define CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS and export
arch_has_restricted_virtio_memory_access to advertize VIRTIO if that's
the case, preventing a host error on access attempt.

Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>
---
 arch/s390/Kconfig   |  1 +
 arch/s390/mm/init.c | 10 ++++++++++
 2 files changed, 11 insertions(+)

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 9cfd8de907cb..c12422c26389 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_VIRTIO_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..5f289ab1b0d2 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -161,6 +161,16 @@ bool force_dma_unencrypted(struct device *dev)
 	return is_prot_virt_guest();
 }
 
+#ifdef CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
+
+int arch_has_restricted_virtio_memory_access(void)
+{
+	return is_prot_virt_guest();
+}
+EXPORT_SYMBOL(arch_has_restricted_virtio_memory_access);
+
+#endif
+
 /* protected virtualization */
 static void pv_init(void)
 {
-- 
2.25.1