Hi Andrew,
On 11/21/18 1:21 PM, Andrew Cooper wrote:
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.coop...@citrix.com>
Acked-by: Julien Grall <julien.gr...@arm.com>
Cheers,
---
CC: Stefano Stabellini <sstabell...@kernel.org>
CC: Julien Grall <julien.gr...@arm.com>
CC: Jan Beulich <jbeul...@suse.com>
CC: Wei Liu <wei.l...@citrix.com>
CC: Roger Pau Monné <roger....@citrix.com>
---
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.
--
Julien Grall
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