3 files changed, 209 insertions, 7 deletions

diff --git a/arch/x86/xen/grant-table.c b/arch/x86/xen/grant-table.c
index c6ab2e7ca3a6..65160a8a0ba3 100644
--- a/arch/x86/xen/grant-table.c
+++ b/arch/x86/xen/grant-table.c
@@ -54,6 +54,20 @@ static int map_pte_fn(pte_t *pte, struct page *pmd_page,
         return 0;
 }
 
+/*
+ * This function is used to map shared frames to store grant status. It is
+ * different from map_pte_fn above, the frames type here is uint64_t.
+ */
+static int map_pte_fn_status(pte_t *pte, struct page *pmd_page,
+                             unsigned long addr, void *data)
+{
+        uint64_t **frames = (uint64_t **)data;
+
+        set_pte_at(&init_mm, addr, pte, mfn_pte((*frames)[0], PAGE_KERNEL));
+        (*frames)++;
+        return 0;
+}
+
 static int unmap_pte_fn(pte_t *pte, struct page *pmd_page,
                         unsigned long addr, void *data)
 {
@@ -83,7 +97,30 @@ int arch_gnttab_map_shared(unsigned long *frames, unsigned long nr_gframes,
         return rc;
 }
 
-void arch_gnttab_unmap_shared(void *shared, unsigned long nr_gframes)
+int arch_gnttab_map_status(uint64_t *frames, unsigned long nr_gframes,
+                           unsigned long max_nr_gframes,
+                           grant_status_t **__shared)
+{
+        int rc;
+        grant_status_t *shared = *__shared;
+
+        if (shared == NULL) {
+                /* No need to pass in PTE as we are going to do it
+                 * in apply_to_page_range anyhow. */
+                struct vm_struct *area =
+                        alloc_vm_area(PAGE_SIZE * max_nr_gframes, NULL);
+                BUG_ON(area == NULL);
+                shared = area->addr;
+                *__shared = shared;
+        }
+
+        rc = apply_to_page_range(&init_mm, (unsigned long)shared,
+                                 PAGE_SIZE * nr_gframes,
+                                 map_pte_fn_status, &frames);
+        return rc;
+}
+
+void arch_gnttab_unmap(void *shared, unsigned long nr_gframes)
 {
         apply_to_page_range(&init_mm, (unsigned long)shared,
                             PAGE_SIZE * nr_gframes, unmap_pte_fn, NULL);
diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 0518d0404942..301869f60dc7 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -44,6 +44,7 @@
 #include <xen/page.h>
 #include <xen/grant_table.h>
 #include <xen/interface/memory.h>
+#include <xen/hvc-console.h>
 #include <asm/xen/hypercall.h>
 
 #include <asm/pgtable.h>
@@ -53,7 +54,10 @@
 /* External tools reserve first few grant table entries. */
 #define NR_RESERVED_ENTRIES 8
 #define GNTTAB_LIST_END 0xffffffff
-#define GREFS_PER_GRANT_FRAME (PAGE_SIZE / sizeof(struct grant_entry_v1))
+#define GREFS_PER_GRANT_FRAME \
+(grant_table_version == 1 ?                      \
+(PAGE_SIZE / sizeof(struct grant_entry_v1)) :   \
+(PAGE_SIZE / sizeof(union grant_entry_v2)))
 
 static grant_ref_t **gnttab_list;
 static unsigned int nr_grant_frames;
@@ -66,6 +70,7 @@ EXPORT_SYMBOL_GPL(xen_hvm_resume_frames);
 
 static union {
         struct grant_entry_v1 *v1;
+        union grant_entry_v2 *v2;
         void *addr;
 } gnttab_shared;
 
@@ -120,6 +125,9 @@ struct gnttab_ops {
 
 static struct gnttab_ops *gnttab_interface;
 
+/*This reflects status of grant entries, so act as a global value*/
+static grant_status_t *grstatus;
+
 static int grant_table_version;
 
 static struct gnttab_free_callback *gnttab_free_callback_list;
@@ -127,6 +135,7 @@ static struct gnttab_free_callback *gnttab_free_callback_list;
 static int gnttab_expand(unsigned int req_entries);
 
 #define RPP (PAGE_SIZE / sizeof(grant_ref_t))
+#define SPP (PAGE_SIZE / sizeof(grant_status_t))
 
 static inline grant_ref_t *__gnttab_entry(grant_ref_t entry)
 {
@@ -199,6 +208,7 @@ static void put_free_entry(grant_ref_t ref)
 }
 
 /*
+ * Following applies to gnttab_update_entry_v1 and gnttab_update_entry_v2.
  * Introducing a valid entry into the grant table:
  *  1. Write ent->domid.
  *  2. Write ent->frame:
@@ -217,6 +227,15 @@ static void gnttab_update_entry_v1(grant_ref_t ref, domid_t domid,
         gnttab_shared.v1[ref].flags = flags;
 }
 
+static void gnttab_update_entry_v2(grant_ref_t ref, domid_t domid,
+                                   unsigned long frame, unsigned flags)
+{
+        gnttab_shared.v2[ref].hdr.domid = domid;
+        gnttab_shared.v2[ref].full_page.frame = frame;
+        wmb();
+        gnttab_shared.v2[ref].hdr.flags = GTF_permit_access | flags;
+}
+
 /*
  * Public grant-issuing interface functions
  */
@@ -248,6 +267,11 @@ static int gnttab_query_foreign_access_v1(grant_ref_t ref)
         return gnttab_shared.v1[ref].flags & (GTF_reading|GTF_writing);
 }
 
+static int gnttab_query_foreign_access_v2(grant_ref_t ref)
+{
+        return grstatus[ref] & (GTF_reading|GTF_writing);
+}
+
 int gnttab_query_foreign_access(grant_ref_t ref)
 {
         return gnttab_interface->query_foreign_access(ref);
@@ -272,6 +296,29 @@ static int gnttab_end_foreign_access_ref_v1(grant_ref_t ref, int readonly)
         return 1;
 }
 
+static int gnttab_end_foreign_access_ref_v2(grant_ref_t ref, int readonly)
+{
+        gnttab_shared.v2[ref].hdr.flags = 0;
+        mb();
+        if (grstatus[ref] & (GTF_reading|GTF_writing)) {
+                return 0;
+        } else {
+                /* The read of grstatus needs to have acquire
+                semantics.  On x86, reads already have
+                that, and we just need to protect against
+                compiler reorderings.  On other
+                architectures we may need a full
+                barrier. */
+#ifdef CONFIG_X86
+                barrier();
+#else
+                mb();
+#endif
+        }
+
+        return 1;
+}
+
 int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
 {
         return gnttab_interface->end_foreign_access_ref(ref, readonly);
@@ -345,6 +392,37 @@ static unsigned long gnttab_end_foreign_transfer_ref_v1(grant_ref_t ref)
         return frame;
 }
 
+static unsigned long gnttab_end_foreign_transfer_ref_v2(grant_ref_t ref)
+{
+        unsigned long frame;
+        u16           flags;
+        u16          *pflags;
+
+        pflags = &gnttab_shared.v2[ref].hdr.flags;
+
+        /*
+         * If a transfer is not even yet started, try to reclaim the grant
+         * reference and return failure (== 0).
+         */
+        while (!((flags = *pflags) & GTF_transfer_committed)) {
+                if (sync_cmpxchg(pflags, flags, 0) == flags)
+                        return 0;
+                cpu_relax();
+        }
+
+        /* If a transfer is in progress then wait until it is completed. */
+        while (!(flags & GTF_transfer_completed)) {
+                flags = *pflags;
+                cpu_relax();
+        }
+
+        rmb();  /* Read the frame number /after/ reading completion status. */
+        frame = gnttab_shared.v2[ref].full_page.frame;
+        BUG_ON(frame == 0);
+
+        return frame;
+}
+
 unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref)
 {
         return gnttab_interface->end_foreign_transfer_ref(ref);
@@ -592,6 +670,11 @@ int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
 }
 EXPORT_SYMBOL_GPL(gnttab_unmap_refs);
 
+static unsigned nr_status_frames(unsigned nr_grant_frames)
+{
+        return (nr_grant_frames * GREFS_PER_GRANT_FRAME + SPP - 1) / SPP;
+}
+
 static int gnttab_map_frames_v1(unsigned long *frames, unsigned int nr_gframes)
 {
         int rc;
@@ -606,7 +689,56 @@ static int gnttab_map_frames_v1(unsigned long *frames, unsigned int nr_gframes)
 
 static void gnttab_unmap_frames_v1(void)
 {
-        arch_gnttab_unmap_shared(gnttab_shared.addr, nr_grant_frames);
+        arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames);
+}
+
+static int gnttab_map_frames_v2(unsigned long *frames, unsigned int nr_gframes)
+{
+        uint64_t *sframes;
+        unsigned int nr_sframes;
+        struct gnttab_get_status_frames getframes;
+        int rc;
+
+        nr_sframes = nr_status_frames(nr_gframes);
+
+        /* No need for kzalloc as it is initialized in following hypercall
+         * GNTTABOP_get_status_frames.
+         */
+        sframes = kmalloc(nr_sframes  * sizeof(uint64_t), GFP_ATOMIC);
+        if (!sframes)
+                return -ENOMEM;
+
+        getframes.dom        = DOMID_SELF;
+        getframes.nr_frames  = nr_sframes;
+        set_xen_guest_handle(getframes.frame_list, sframes);
+
+        rc = HYPERVISOR_grant_table_op(GNTTABOP_get_status_frames,
+                                       &getframes, 1);
+        if (rc == -ENOSYS) {
+                kfree(sframes);
+                return -ENOSYS;
+        }
+
+        BUG_ON(rc || getframes.status);
+
+        rc = arch_gnttab_map_status(sframes, nr_sframes,
+                                    nr_status_frames(gnttab_max_grant_frames()),
+                                    &grstatus);
+        BUG_ON(rc);
+        kfree(sframes);
+
+        rc = arch_gnttab_map_shared(frames, nr_gframes,
+                                    gnttab_max_grant_frames(),
+                                    &gnttab_shared.addr);
+        BUG_ON(rc);
+
+        return 0;
+}
+
+static void gnttab_unmap_frames_v2(void)
+{
+        arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames);
+        arch_gnttab_unmap(grstatus, nr_status_frames(nr_grant_frames));
 }
 
 static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
@@ -640,6 +772,9 @@ static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
                 return rc;
         }
 
+        /* No need for kzalloc as it is initialized in following hypercall
+         * GNTTABOP_setup_table.
+         */
         frames = kmalloc(nr_gframes * sizeof(unsigned long), GFP_ATOMIC);
         if (!frames)
                 return -ENOMEM;
@@ -672,10 +807,38 @@ static struct gnttab_ops gnttab_v1_ops = {
         .query_foreign_access           = gnttab_query_foreign_access_v1,
 };
 
+static struct gnttab_ops gnttab_v2_ops = {
+        .map_frames                     = gnttab_map_frames_v2,
+        .unmap_frames                   = gnttab_unmap_frames_v2,
+        .update_entry                   = gnttab_update_entry_v2,
+        .end_foreign_access_ref         = gnttab_end_foreign_access_ref_v2,
+        .end_foreign_transfer_ref       = gnttab_end_foreign_transfer_ref_v2,
+        .query_foreign_access           = gnttab_query_foreign_access_v2,
+};
+
 static void gnttab_request_version(void)
 {
-        grant_table_version = 1;
-        gnttab_interface = &gnttab_v1_ops;
+        int rc;
+        struct gnttab_set_version gsv;
+
+        gsv.version = 2;
+        rc = HYPERVISOR_grant_table_op(GNTTABOP_set_version, &gsv, 1);
+        if (rc == 0) {
+                grant_table_version = 2;
+                gnttab_interface = &gnttab_v2_ops;
+        } else if (grant_table_version == 2) {
+                /*
+                 * If we've already used version 2 features,
+                 * but then suddenly discover that they're not
+                 * available (e.g. migrating to an older
+                 * version of Xen), almost unbounded badness
+                 * can happen.
+                 */
+                panic("we need grant tables version 2, but only version 1 is available");
+        } else {
+                grant_table_version = 1;
+                gnttab_interface = &gnttab_v1_ops;
+        }
         printk(KERN_INFO "Grant tables using version %d layout.\n",
                 grant_table_version);
 }
diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h
index c7a40f8d455a..5494c402c83a 100644
--- a/include/xen/grant_table.h
+++ b/include/xen/grant_table.h
@@ -146,8 +146,10 @@ gnttab_set_unmap_op(struct gnttab_unmap_grant_ref *unmap, phys_addr_t addr,
 int arch_gnttab_map_shared(unsigned long *frames, unsigned long nr_gframes,
                            unsigned long max_nr_gframes,
                            void **__shared);
-void arch_gnttab_unmap_shared(void *shared,
-                              unsigned long nr_gframes);
+int arch_gnttab_map_status(uint64_t *frames, unsigned long nr_gframes,
+                           unsigned long max_nr_gframes,
+                           grant_status_t **__shared);
+void arch_gnttab_unmap(void *shared, unsigned long nr_gframes);
 
 extern unsigned long xen_hvm_resume_frames;
 unsigned int gnttab_max_grant_frames(void);