drivers: xen: memory: add acquire_resource wrapper

Add XENMEM_acquire_resource wrapper to map device model related buffers.
This is required for communication with the ioreq server.

- memory
  - xendom_acquire_resource:
    HYPERVISOR_memory_op(XENMEM_acquire_resource)

Signed-off-by: TOKITA Hiroshi <[email protected]>

Author: soburi

drivers/xen/memory.c

@@ -66,3 +66,25 @@ int xendom_populate_physmap(int domid, unsigned int extent_order,
 
 	return HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
 }
+
+int xendom_acquire_resource(domid_t domid, uint16_t type, uint32_t id, uint64_t frame,
+			    uint32_t *nr_frames, xen_pfn_t *frame_list)
+{
+	struct xen_mem_acquire_resource acquire_res = {
+		.domid = domid,
+		.type = type,
+		.id = id,
+		.pad = 0,
+		.frame = frame,
+		.nr_frames = *nr_frames,
+	};
+	int ret;
+
+	set_xen_guest_handle(acquire_res.frame_list, frame_list);
+
+	ret = HYPERVISOR_memory_op(XENMEM_acquire_resource, &acquire_res);
+
+	*nr_frames = acquire_res.nr_frames;
+
+	return ret;
+}

include/zephyr/xen/memory.h

@@ -3,6 +3,9 @@
  * Copyright (c) 2023 EPAM Systems
  */
 
+#ifndef ZEPHYR_XEN_MEMORY_H_
+#define ZEPHYR_XEN_MEMORY_H_
+
 #include <zephyr/kernel.h>
 #include <zephyr/xen/public/memory.h>
 #include <zephyr/xen/public/xen.h>
@@ -64,3 +67,25 @@ int xendom_remove_from_physmap(int domid, xen_pfn_t gpfn);
 int xendom_populate_physmap(int domid, unsigned int extent_order,
 			    unsigned int nr_extents, unsigned int mem_flags,
 			    xen_pfn_t *extent_start);
+
+/**
+ * @brief Acquire a resource mapping for the Xen domain.
+ *
+ * Issues the XENMEM_acquire_resource hypercall to map a resource buffer
+ * (e.g., I/O request server, grant table, VM trace buffer) into the
+ * specified domain's physmap, or query its total size.
+ *
+ * @param domid        Target domain identifier. Use DOMID_SELF for the calling domain.
+ * @param type         Resource type identifier (e.g., XENMEM_resource_ioreq_server).
+ * @param id           Resource-specific identifier (e.g., server ID or table ID).
+ * @param frame        Starting frame number for mapping, or ignored if *nr_frames == 0.
+ * @param nr_frames    [in,out] On input, number of frames to map; on return,
+ *                     number of frames actually mapped (or total frames if queried).
+ * @param frame_list   Guest frame list buffer: input GFNs for HVM guests,
+ *                     output MFNs for PV guests.
+ * @return             Zero on success, or a negative errno code on failure.
+ */
+int xendom_acquire_resource(domid_t domid, uint16_t type, uint32_t id, uint64_t frame,
+			    uint32_t *nr_frames, xen_pfn_t *frame_list);
+
+#endif /* ZEPHYR_XEN_MEMORY_H_ */

include/zephyr/xen/public/memory.h

@@ -161,4 +161,82 @@ struct xen_remove_from_physmap {
 typedef struct xen_remove_from_physmap xen_remove_from_physmap_t;
 DEFINE_XEN_GUEST_HANDLE(xen_remove_from_physmap_t);
 
+/*
+ * Get the pages for a particular guest resource, so that they can be
+ * mapped directly by a tools domain.
+ */
+#define XENMEM_acquire_resource 28
+struct xen_mem_acquire_resource {
+	/* IN - The domain whose resource is to be mapped */
+	domid_t domid;
+	/* IN - the type of resource */
+	uint16_t type;
+
+#define XENMEM_resource_ioreq_server 0
+#define XENMEM_resource_grant_table 1
+#define XENMEM_resource_vmtrace_buf 2
+
+	/*
+	 * IN - a type-specific resource identifier, which must be zero
+	 *      unless stated otherwise.
+	 *
+	 * type == XENMEM_resource_ioreq_server -> id == ioreq server id
+	 * type == XENMEM_resource_grant_table -> id defined below
+	 */
+	uint32_t id;
+
+#define XENMEM_resource_grant_table_id_shared 0
+#define XENMEM_resource_grant_table_id_status 1
+
+	/*
+	 * IN/OUT
+	 *
+	 * As an IN parameter number of frames of the resource to be mapped.
+	 * This value may be updated over the course of the operation.
+	 *
+	 * When frame_list is NULL and nr_frames is 0, this is interpreted as a
+	 * request for the size of the resource, which shall be returned in the
+	 * nr_frames field.
+	 *
+	 * The size of a resource will never be zero, but a nonzero result doesn't
+	 * guarantee that a subsequent mapping request will be successful.  There
+	 * are further type/id specific constraints which may change between the
+	 * two calls.
+	 */
+	uint32_t nr_frames;
+	/*
+	 * Padding field, must be zero on input.
+	 * In a previous version this was an output field with the lowest bit
+	 * named XENMEM_rsrc_acq_caller_owned. Future versions of this interface
+	 * will not reuse this bit as an output with the field being zero on
+	 * input.
+	 */
+	uint32_t pad;
+	/*
+	 * IN - the index of the initial frame to be mapped. This parameter
+	 *      is ignored if nr_frames is 0.  This value may be updated
+	 *      over the course of the operation.
+	 */
+	uint64_t frame;
+
+#define XENMEM_resource_ioreq_server_frame_bufioreq 0
+#define XENMEM_resource_ioreq_server_frame_ioreq(n) (1 + (n))
+
+	/*
+	 * IN/OUT - If the tools domain is PV then, upon return, frame_list
+	 *          will be populated with the MFNs of the resource.
+	 *          If the tools domain is HVM then it is expected that, on
+	 *          entry, frame_list will be populated with a list of GFNs
+	 *          that will be mapped to the MFNs of the resource.
+	 *          If -EIO is returned then the frame_list has only been
+	 *          partially mapped and it is up to the caller to unmap all
+	 *          the GFNs.
+	 *          This parameter may be NULL if nr_frames is 0.  This
+	 *          value may be updated over the course of the operation.
+	 */
+	XEN_GUEST_HANDLE(xen_pfn_t) frame_list;
+};
+typedef struct xen_mem_acquire_resource xen_mem_acquire_resource_t;
+DEFINE_XEN_GUEST_HANDLE(xen_mem_acquire_resource_t);
+
 #endif /* __XEN_PUBLIC_MEMORY_H__ */