xen/virtio: enable grant based virtio on x86

Use an x86-specific virtio_check_mem_acc_cb() for Xen in order to setup
the correct DMA ops.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> # common code
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>

arch/x86/xen/enlighten_hvm.c

@@ -212,7 +212,7 @@ static void __init xen_hvm_guest_init(void)
 		return;
 
 	if (IS_ENABLED(CONFIG_XEN_VIRTIO_FORCE_GRANT))
-		virtio_set_mem_acc_cb(virtio_require_restricted_mem_acc);
+		virtio_set_mem_acc_cb(xen_virtio_restricted_mem_acc);
 
 	init_hvm_pv_info();
 

arch/x86/xen/enlighten_pv.c

@@ -112,7 +112,7 @@ static void __init xen_pv_init_platform(void)
 {
 	/* PV guests can't operate virtio devices without grants. */
 	if (IS_ENABLED(CONFIG_XEN_VIRTIO))
-		virtio_set_mem_acc_cb(virtio_require_restricted_mem_acc);
+		virtio_set_mem_acc_cb(xen_virtio_restricted_mem_acc);
 
 	populate_extra_pte(fix_to_virt(FIX_PARAVIRT_BOOTMAP));
 

drivers/xen/grant-dma-ops.c

@@ -313,7 +313,7 @@ bool xen_is_grant_dma_device(struct device *dev)
 
 bool xen_virtio_mem_acc(struct virtio_device *dev)
 {
-	if (IS_ENABLED(CONFIG_XEN_VIRTIO_FORCE_GRANT))
+	if (IS_ENABLED(CONFIG_XEN_VIRTIO_FORCE_GRANT) || xen_pv_domain())
 		return true;
 
 	return xen_is_grant_dma_device(dev->dev.parent);
@@ -387,6 +387,16 @@ void xen_grant_setup_dma_ops(struct device *dev)
 	dev_err(dev, "Cannot set up Xen grant DMA ops, retain platform DMA ops\n");
 }
 
+bool xen_virtio_restricted_mem_acc(struct virtio_device *dev)
+{
+	bool ret = xen_virtio_mem_acc(dev);
+
+	if (ret)
+		xen_grant_setup_dma_ops(dev->dev.parent);
+
+	return ret;
+}
+
 MODULE_DESCRIPTION("Xen grant DMA-mapping layer");
 MODULE_AUTHOR("Juergen Gross <jgross@suse.com>");
 MODULE_LICENSE("GPL");

include/xen/xen-ops.h

@@ -219,6 +219,7 @@ static inline void xen_preemptible_hcall_end(void) { }
 void xen_grant_setup_dma_ops(struct device *dev);
 bool xen_is_grant_dma_device(struct device *dev);
 bool xen_virtio_mem_acc(struct virtio_device *dev);
+bool xen_virtio_restricted_mem_acc(struct virtio_device *dev);
 #else
 static inline void xen_grant_setup_dma_ops(struct device *dev)
 {
@@ -234,6 +235,11 @@ static inline bool xen_virtio_mem_acc(struct virtio_device *dev)
 {
 	return false;
 }
+
+static inline bool xen_virtio_restricted_mem_acc(struct virtio_device *dev)
+{
+	return false;
+}
 #endif /* CONFIG_XEN_GRANT_DMA_OPS */
 
 #endif /* INCLUDE_XEN_OPS_H */