Xen/gnttab: introduce common INVALID_GRANT_{HANDLE,REF}

It's not helpful if every driver has to cook its own. Generalize
xenbus'es INVALID_GRANT_HANDLE and pcifront's INVALID_GRANT_REF (which
shouldn't have expanded to zero to begin with). Use the constants in
p2m.c and gntdev.c right away, and update field types where necessary so
they would match with the constants' types (albeit without touching
struct ioctl_gntdev_grant_ref's ref field, as that's part of the public
interface of the kernel and would require introducing a dependency on
Xen's grant_table.h public header).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/db7c38a5-0d75-d5d1-19de-e5fe9f0b9c48@suse.com
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

diff --git a/arch/arm/xen/p2m.c b/arch/arm/xen/p2m.c
index 5316cf36cb57ebff4d86cf4bd5c33427973a167b..84a1cea1f43b9a3331b35093e4c57cb78d670815 100644 (file)
--- a/arch/arm/xen/p2m.c
+++ b/arch/arm/xen/p2m.c
@@ -11,6 +11,7 @@
 
 #include <xen/xen.h>
 #include <xen/interface/memory.h>
+#include <xen/grant_table.h>
 #include <xen/page.h>
 #include <xen/swiotlb-xen.h>
 
@@ -109,7 +110,7 @@ int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
                map_ops[i].status = GNTST_general_error;
                unmap.host_addr = map_ops[i].host_addr,
                unmap.handle = map_ops[i].handle;
-               map_ops[i].handle = ~0;
+               map_ops[i].handle = INVALID_GRANT_HANDLE;
                if (map_ops[i].flags & GNTMAP_device_map)
                        unmap.dev_bus_addr = map_ops[i].dev_bus_addr;
                else

diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index e912992e0b77f1d0a0a64328846ea1bcc951f8a6..17d80f751fcb2477fa16799261c6db8823941fcc 100644 (file)
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -741,7 +741,7 @@ int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
                map_ops[i].status = GNTST_general_error;
                unmap[0].host_addr = map_ops[i].host_addr,
                unmap[0].handle = map_ops[i].handle;
-               map_ops[i].handle = ~0;
+               map_ops[i].handle = INVALID_GRANT_HANDLE;
                if (map_ops[i].flags & GNTMAP_device_map)
                        unmap[0].dev_bus_addr = map_ops[i].dev_bus_addr;
                else
@@ -751,7 +751,7 @@ int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
                        kmap_ops[i].status = GNTST_general_error;
                        unmap[1].host_addr = kmap_ops[i].host_addr,
                        unmap[1].handle = kmap_ops[i].handle;
-                       kmap_ops[i].handle = ~0;
+                       kmap_ops[i].handle = INVALID_GRANT_HANDLE;
                        if (kmap_ops[i].flags & GNTMAP_device_map)
                                unmap[1].dev_bus_addr = kmap_ops[i].dev_bus_addr;
                        else

diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
index c6fe0cfec0f681f19cabecc0826627e5d6018f2f..2d75026482197de191e13b73f39f3f4ba09ce79f 100644 (file)
--- a/drivers/pci/xen-pcifront.c
+++ b/drivers/pci/xen-pcifront.c
@@ -26,7 +26,7 @@
 #include <xen/platform_pci.h>
 
 #include <asm/xen/swiotlb-xen.h>
-#define INVALID_GRANT_REF (0)
+
 #define INVALID_EVTCHN    (-1)
 
 struct pci_bus_entry {
@@ -42,7 +42,7 @@ struct pcifront_device {
        struct list_head root_buses;
 
        int evtchn;
-       int gnt_ref;
+       grant_ref_t gnt_ref;
 
        int irq;
 

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index b60ebd8bdb2616fb48f816aa19b60f79dbd4232a..ebfd3e7b20d47f9a2ba9e4f5cd6cc37b7e07ef2c 100644 (file)
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -186,11 +186,11 @@ struct gntdev_grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count,
                goto err;
 
        for (i = 0; i < count; i++) {
-               add->map_ops[i].handle = -1;
-               add->unmap_ops[i].handle = -1;
+               add->map_ops[i].handle = INVALID_GRANT_HANDLE;
+               add->unmap_ops[i].handle = INVALID_GRANT_HANDLE;
                if (use_ptemod) {
-                       add->kmap_ops[i].handle = -1;
-                       add->kunmap_ops[i].handle = -1;
+                       add->kmap_ops[i].handle = INVALID_GRANT_HANDLE;
+                       add->kunmap_ops[i].handle = INVALID_GRANT_HANDLE;
                }
        }
 
@@ -279,7 +279,7 @@ static int find_grant_ptes(pte_t *pte, unsigned long addr, void *data)
                          map->grants[pgnr].ref,
                          map->grants[pgnr].domid);
        gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags,
-                           -1 /* handle */);
+                           INVALID_GRANT_HANDLE);
        return 0;
 }
 
@@ -297,7 +297,7 @@ int gntdev_map_grant_pages(struct gntdev_grant_map *map)
 
        if (!use_ptemod) {
                /* Note: it could already be mapped */
-               if (map->map_ops[0].handle != -1)
+               if (map->map_ops[0].handle != INVALID_GRANT_HANDLE)
                        return 0;
                for (i = 0; i < map->count; i++) {
                        unsigned long addr = (unsigned long)
@@ -306,7 +306,7 @@ int gntdev_map_grant_pages(struct gntdev_grant_map *map)
                                map->grants[i].ref,
                                map->grants[i].domid);
                        gnttab_set_unmap_op(&map->unmap_ops[i], addr,
-                               map->flags, -1 /* handle */);
+                               map->flags, INVALID_GRANT_HANDLE);
                }
        } else {
                /*
@@ -332,7 +332,7 @@ int gntdev_map_grant_pages(struct gntdev_grant_map *map)
                                map->grants[i].ref,
                                map->grants[i].domid);
                        gnttab_set_unmap_op(&map->kunmap_ops[i], address,
-                               flags, -1);
+                               flags, INVALID_GRANT_HANDLE);
                }
        }
 
@@ -390,7 +390,7 @@ static int __unmap_grant_pages(struct gntdev_grant_map *map, int offset,
                pr_debug("unmap handle=%d st=%d\n",
                        map->unmap_ops[offset+i].handle,
                        map->unmap_ops[offset+i].status);
-               map->unmap_ops[offset+i].handle = -1;
+               map->unmap_ops[offset+i].handle = INVALID_GRANT_HANDLE;
        }
        return err;
 }
@@ -406,13 +406,15 @@ static int unmap_grant_pages(struct gntdev_grant_map *map, int offset,
         * already unmapped some of the grants. Only unmap valid ranges.
         */
        while (pages && !err) {
-               while (pages && map->unmap_ops[offset].handle == -1) {
+               while (pages &&
+                      map->unmap_ops[offset].handle == INVALID_GRANT_HANDLE) {
                        offset++;
                        pages--;
                }
                range = 0;
                while (range < pages) {
-                       if (map->unmap_ops[offset+range].handle == -1)
+                       if (map->unmap_ops[offset + range].handle ==
+                           INVALID_GRANT_HANDLE)
                                break;
                        range++;
                }

diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h
index 0b1182a3cf4128b4502b7e3db59adeb8522daea5..cb854df031ce0715b9158fa71c7f02ad2c2dc732 100644 (file)
--- a/include/xen/grant_table.h
+++ b/include/xen/grant_table.h
@@ -50,6 +50,13 @@
 #include <linux/page-flags.h>
 #include <linux/kernel.h>
 
+/*
+ * Technically there's no reliably invalid grant reference or grant handle,
+ * so pick the value that is the most unlikely one to be observed valid.
+ */
+#define INVALID_GRANT_REF          ((grant_ref_t)-1)
+#define INVALID_GRANT_HANDLE       ((grant_handle_t)-1)
+
 #define GNTTAB_RESERVED_XENSTORE 1
 
 /* NR_GRANT_FRAMES must be less than or equal to that configured in Xen */

diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h
index 0b1386073d49bf48d40909954d6043e15a27638d..b94074c827721b8ebdee18a5199ba3657cfcccfd 100644 (file)
--- a/include/xen/xenbus.h
+++ b/include/xen/xenbus.h
@@ -51,7 +51,6 @@
 
 #define XENBUS_MAX_RING_GRANT_ORDER 4
 #define XENBUS_MAX_RING_GRANTS      (1U << XENBUS_MAX_RING_GRANT_ORDER)
-#define INVALID_GRANT_HANDLE       (~0U)
 
 /* Register callback to watch this node. */
 struct xenbus_watch