xen/privcmd: add IOCTL_PRIVCMD_MMAP_RESOURCE

My recent Xen patch series introduces a new HYPERVISOR_memory_op to
support direct priv-mapping of certain guest resources (such as ioreq
pages, used by emulators) by a tools domain, rather than having to access
such resources via the guest P2M.

This patch adds the necessary infrastructure to the privcmd driver and
Xen MMU code to support direct resource mapping.

NOTE: The adjustment in the MMU code is partially cosmetic. Xen will now
      allow a PV tools domain to map guest pages either by GFN or MFN, thus
      the term 'mfn' has been swapped for 'pfn' in the lower layers of the
      remap code.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>

2 files changed, 70 insertions, 3 deletions

diff --git a/include/xen/interface/memory.h b/include/xen/interface/memory.h
index 583dd93b3016..4c5751c26f87 100644
--- a/include/xen/interface/memory.h
+++ b/include/xen/interface/memory.h
@@ -265,4 +265,70 @@ struct xen_remove_from_physmap {
 };
 DEFINE_GUEST_HANDLE_STRUCT(xen_remove_from_physmap);
 
+/*
+ * 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
+
+    /*
+     * 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. However, if the specified value is 0 and
+     *          frame_list is NULL then this field will be set to the
+     *          maximum value supported by the implementation on return.
+     */
+    uint32_t nr_frames;
+    /*
+     * OUT - Must be zero on entry. On return this may contain a bitwise
+     *       OR of the following values.
+     */
+    uint32_t flags;
+
+    /* The resource pages have been assigned to the calling domain */
+#define _XENMEM_rsrc_acq_caller_owned 0
+#define XENMEM_rsrc_acq_caller_owned (1u << _XENMEM_rsrc_acq_caller_owned)
+
+    /*
+     * IN - the index of the initial frame to be mapped. This parameter
+     *      is ignored if nr_frames is 0.
+     */
+    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.
+     */
+    GUEST_HANDLE(xen_pfn_t) frame_list;
+};
+DEFINE_GUEST_HANDLE_STRUCT(xen_mem_acquire_resource);
+
 #endif /* __XEN_PUBLIC_MEMORY_H__ */
diff --git a/include/xen/interface/xen.h b/include/xen/interface/xen.h
index 4f4830ef8f93..8bfb242f433e 100644
--- a/include/xen/interface/xen.h
+++ b/include/xen/interface/xen.h
@@ -265,9 +265,10 @@
  *
  * PAT (bit 7 on) --> PWT (bit 3 on) and clear bit 7.
  */
-#define MMU_NORMAL_PT_UPDATE      0 /* checked '*ptr = val'. ptr is MA.       */
-#define MMU_MACHPHYS_UPDATE       1 /* ptr = MA of frame to modify entry for  */
-#define MMU_PT_UPDATE_PRESERVE_AD 2 /* atomically: *ptr = val | (*ptr&(A|D)) */
+#define MMU_NORMAL_PT_UPDATE       0 /* checked '*ptr = val'. ptr is MA.      */
+#define MMU_MACHPHYS_UPDATE        1 /* ptr = MA of frame to modify entry for */
+#define MMU_PT_UPDATE_PRESERVE_AD  2 /* atomically: *ptr = val | (*ptr&(A|D)) */
+#define MMU_PT_UPDATE_NO_TRANSLATE 3 /* checked '*ptr = val'. ptr is MA.      */
 
 /*
  * MMU EXTENDED OPERATIONS