[Xen-devel] [PATCH 08/14] xen/memory: Drop ARM put_gfn() stub

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On x86, get_gfn_*() and put_gfn() are reference counting pairs.  All the
get_gfn_*() functions are called from within CONFIG_X86 sections, but
put_gfn() is stubbed out on ARM.

As a result, the common code reads as if ARM is dropping references it never
acquired.

Put all put_gfn() calls in common code inside CONFIG_X86 to make the code
properly balanced, and drop the ARM stub.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
CC: Julien Grall <julien.grall@xxxxxxx>
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 xen/common/grant_table.c |  8 ++++++++
 xen/common/memory.c      | 15 ++++++++++++++-
 xen/include/asm-arm/mm.h |  2 --
 3 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c
index fc41b65..f7860f6 100644
--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -2110,7 +2110,9 @@ gnttab_transfer(
         /* Check the passed page frame for basic validity. */
         if ( unlikely(!mfn_valid(mfn)) )
         {
+#ifdef CONFIG_X86
             put_gfn(d, gop.mfn);
+#endif
             gdprintk(XENLOG_INFO, "out-of-range %lx\n", (unsigned 
long)gop.mfn);
             gop.status = GNTST_bad_page;
             goto copyback;
@@ -2119,7 +2121,9 @@ gnttab_transfer(
         page = mfn_to_page(mfn);
         if ( (rc = steal_page(d, page, 0)) < 0 )
         {
+#ifdef CONFIG_X86
             put_gfn(d, gop.mfn);
+#endif
             gop.status = rc == -EINVAL ? GNTST_bad_page : GNTST_general_error;
             goto copyback;
         }
@@ -2149,7 +2153,9 @@ gnttab_transfer(
         unlock_and_copyback:
             rcu_unlock_domain(e);
         put_gfn_and_copyback:
+#ifdef CONFIG_X86
             put_gfn(d, gop.mfn);
+#endif
             page->count_info &= ~(PGC_count_mask|PGC_allocated);
             free_domheap_page(page);
             goto copyback;
@@ -2236,7 +2242,9 @@ gnttab_transfer(
         page_set_owner(page, e);
 
         spin_unlock(&e->page_alloc_lock);
+#ifdef CONFIG_X86
         put_gfn(d, gop.mfn);
+#endif
 
         TRACE_1D(TRC_MEM_PAGE_GRANT_TRANSFER, e->domain_id);
 
diff --git a/xen/common/memory.c b/xen/common/memory.c
index 58194b9..175bd62 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -358,7 +358,9 @@ int guest_remove_page(struct domain *d, unsigned long gmfn)
 #endif
     if ( unlikely(!mfn_valid(mfn)) )
     {
+#ifdef CONFIG_X86
         put_gfn(d, gmfn);
+#endif
         gdprintk(XENLOG_INFO, "Domain %u page number %lx invalid\n",
                 d->domain_id, gmfn);
 
@@ -388,7 +390,9 @@ int guest_remove_page(struct domain *d, unsigned long gmfn)
     page = mfn_to_page(mfn);
     if ( unlikely(!get_page(page, d)) )
     {
+#ifdef CONFIG_X86
         put_gfn(d, gmfn);
+#endif
         gdprintk(XENLOG_INFO, "Bad page free for domain %u\n", d->domain_id);
 
         return -ENXIO;
@@ -409,8 +413,11 @@ int guest_remove_page(struct domain *d, unsigned long gmfn)
         put_page(page);
 
     put_page(page);
- out_put_gfn: __maybe_unused;
+
+#ifdef CONFIG_X86
+ out_put_gfn:
     put_gfn(d, gmfn);
+#endif
 
     /*
      * Filter out -ENOENT return values that aren't a result of an empty p2m
@@ -656,7 +663,9 @@ static long 
memory_exchange(XEN_GUEST_HANDLE_PARAM(xen_memory_exchange_t) arg)
 #endif
                 if ( unlikely(!mfn_valid(mfn)) )
                 {
+#ifdef CONFIG_X86
                     put_gfn(d, gmfn + k);
+#endif
                     rc = -EINVAL;
                     goto fail;
                 }
@@ -666,12 +675,16 @@ static long 
memory_exchange(XEN_GUEST_HANDLE_PARAM(xen_memory_exchange_t) arg)
                 rc = steal_page(d, page, MEMF_no_refcount);
                 if ( unlikely(rc) )
                 {
+#ifdef CONFIG_X86
                     put_gfn(d, gmfn + k);
+#endif
                     goto fail;
                 }
 
                 page_list_add(page, &in_chunk_list);
+#ifdef CONFIG_X86
                 put_gfn(d, gmfn + k);
+#endif
             }
         }
 
diff --git a/xen/include/asm-arm/mm.h b/xen/include/asm-arm/mm.h
index 940b74b..b2f6104 100644
--- a/xen/include/asm-arm/mm.h
+++ b/xen/include/asm-arm/mm.h
@@ -313,8 +313,6 @@ static inline void *page_to_virt(const struct page_info *pg)
 struct page_info *get_page_from_gva(struct vcpu *v, vaddr_t va,
                                     unsigned long flags);
 
-static inline void put_gfn(struct domain *d, unsigned long gfn) {}
-
 /*
  * Arm does not have an M2P, but common code expects a handful of
  * M2P-related defines and functions. Provide dummy versions of these.
-- 
2.1.4


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