[RFC 46/48] riscv/virtio: Have CoVE guests enforce restricted virtio memory access.

[Atish Patra]

From: Rajnesh Kanwal <rkanwal at rivosinc.com>

CoVE guest requires that virtio devices use the DMA API to allow the
hypervisor to successfully access guest memory as needed.

The VIRTIO_F_VERSION_1 and VIRTIO_F_ACCESS_PLATFORM features tell virtio
to use the DMA API. Force to check for these features to fail the device
probe if these features have not been set when running as an TEE guest.

Signed-off-by: Rajnesh Kanwal <rkanwal at rivosinc.com>
---
 arch/riscv/mm/mem_encrypt.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/riscv/mm/mem_encrypt.c b/arch/riscv/mm/mem_encrypt.c
index 8207a5c..8523c50 100644
--- a/arch/riscv/mm/mem_encrypt.c
+++ b/arch/riscv/mm/mem_encrypt.c
@@ -10,6 +10,7 @@
 #include <linux/swiotlb.h>
 #include <linux/cc_platform.h>
 #include <linux/mem_encrypt.h>
+#include <linux/virtio_anchor.h>
 #include <asm/covg_sbi.h>
 
 /* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */
@@ -54,4 +55,7 @@ void __init mem_encrypt_init(void)
 
 	/* Call into SWIOTLB to update the SWIOTLB DMA buffers */
 	swiotlb_update_mem_attributes();
+
+	/* Set restricted memory access for virtio. */
+	virtio_set_mem_acc_cb(virtio_require_restricted_mem_acc);
 }
-- 
2.25.1