From: David Hildenbrand <david@redhat.com>
To: qemu-devel@nongnu.org
Cc: "Marcel Apfelbaum" <mapfelba@redhat.com>,
"Murilo Opsfelder Araujo" <muriloo@linux.ibm.com>,
"Igor Kotrasinski" <i.kotrasinsk@partner.samsung.com>,
"Eduardo Habkost" <ehabkost@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
"David Hildenbrand" <david@redhat.com>,
"Richard Henderson" <richard.henderson@linaro.org>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
"Peter Xu" <peterx@redhat.com>, "Greg Kurz" <groug@kaod.org>,
"Stefan Hajnoczi" <stefanha@redhat.com>,
"Igor Mammedov" <imammedo@redhat.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Nitesh Lal" <nilal@redhat.com>,
"Philippe Mathieu-Daudé" <philmd@redhat.com>
Subject: [PATCH v7 01/15] util/mmap-alloc: Factor out calculation of the pagesize for the guard page
Date: Wed, 28 Apr 2021 15:37:40 +0200 [thread overview]
Message-ID: <20210428133754.10713-2-david@redhat.com> (raw)
In-Reply-To: <20210428133754.10713-1-david@redhat.com>
Let's factor out calculating the size of the guard page and rename the
variable to make it clearer that this pagesize only applies to the
guard page.
Reviewed-by: Peter Xu <peterx@redhat.com>
Acked-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
Acked-by: Eduardo Habkost <ehabkost@redhat.com> for memory backend and machine core
Cc: Igor Kotrasinski <i.kotrasinsk@partner.samsung.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
util/mmap-alloc.c | 31 ++++++++++++++++---------------
1 file changed, 16 insertions(+), 15 deletions(-)
diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c
index e6fa8b598b..24854064b4 100644
--- a/util/mmap-alloc.c
+++ b/util/mmap-alloc.c
@@ -82,6 +82,16 @@ size_t qemu_mempath_getpagesize(const char *mem_path)
return qemu_real_host_page_size;
}
+static inline size_t mmap_guard_pagesize(int fd)
+{
+#if defined(__powerpc64__) && defined(__linux__)
+ /* Mappings in the same segment must share the same page size */
+ return qemu_fd_getpagesize(fd);
+#else
+ return qemu_real_host_page_size;
+#endif
+}
+
void *qemu_ram_mmap(int fd,
size_t size,
size_t align,
@@ -90,12 +100,12 @@ void *qemu_ram_mmap(int fd,
bool is_pmem,
off_t map_offset)
{
+ const size_t guard_pagesize = mmap_guard_pagesize(fd);
int prot;
int flags;
int map_sync_flags = 0;
int guardfd;
size_t offset;
- size_t pagesize;
size_t total;
void *guardptr;
void *ptr;
@@ -116,8 +126,7 @@ void *qemu_ram_mmap(int fd,
* anonymous memory is OK.
*/
flags = MAP_PRIVATE;
- pagesize = qemu_fd_getpagesize(fd);
- if (fd == -1 || pagesize == qemu_real_host_page_size) {
+ if (fd == -1 || guard_pagesize == qemu_real_host_page_size) {
guardfd = -1;
flags |= MAP_ANONYMOUS;
} else {
@@ -126,7 +135,6 @@ void *qemu_ram_mmap(int fd,
}
#else
guardfd = -1;
- pagesize = qemu_real_host_page_size;
flags = MAP_PRIVATE | MAP_ANONYMOUS;
#endif
@@ -138,7 +146,7 @@ void *qemu_ram_mmap(int fd,
assert(is_power_of_2(align));
/* Always align to host page size */
- assert(align >= pagesize);
+ assert(align >= guard_pagesize);
flags = MAP_FIXED;
flags |= fd == -1 ? MAP_ANONYMOUS : 0;
@@ -193,8 +201,8 @@ void *qemu_ram_mmap(int fd,
* a guard page guarding against potential buffer overflows.
*/
total -= offset;
- if (total > size + pagesize) {
- munmap(ptr + size + pagesize, total - size - pagesize);
+ if (total > size + guard_pagesize) {
+ munmap(ptr + size + guard_pagesize, total - size - guard_pagesize);
}
return ptr;
@@ -202,15 +210,8 @@ void *qemu_ram_mmap(int fd,
void qemu_ram_munmap(int fd, void *ptr, size_t size)
{
- size_t pagesize;
-
if (ptr) {
/* Unmap both the RAM block and the guard page */
-#if defined(__powerpc64__) && defined(__linux__)
- pagesize = qemu_fd_getpagesize(fd);
-#else
- pagesize = qemu_real_host_page_size;
-#endif
- munmap(ptr, size + pagesize);
+ munmap(ptr, size + mmap_guard_pagesize(fd));
}
}
--
2.30.2
next prev parent reply other threads:[~2021-04-28 13:43 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-28 13:37 [PATCH v7 00/15] RAM_NORESERVE, MAP_NORESERVE and hostmem "reserve" property David Hildenbrand
2021-04-28 13:37 ` David Hildenbrand [this message]
2021-04-28 13:37 ` [PATCH v7 02/15] util/mmap-alloc: Factor out reserving of a memory region to mmap_reserve() David Hildenbrand
2021-04-28 13:37 ` [PATCH v7 03/15] util/mmap-alloc: Factor out activating of memory to mmap_activate() David Hildenbrand
2021-04-28 13:37 ` [PATCH v7 04/15] softmmu/memory: Pass ram_flags to qemu_ram_alloc_from_fd() David Hildenbrand
2021-04-28 13:37 ` [PATCH v7 05/15] softmmu/memory: Pass ram_flags to memory_region_init_ram_shared_nomigrate() David Hildenbrand
2021-04-28 13:37 ` [PATCH v7 06/15] softmmu/memory: Pass ram_flags to qemu_ram_alloc() and qemu_ram_alloc_internal() David Hildenbrand
2021-04-28 13:37 ` [PATCH v7 07/15] util/mmap-alloc: Pass flags instead of separate bools to qemu_ram_mmap() David Hildenbrand
2021-04-28 13:37 ` [PATCH v7 08/15] memory: Introduce RAM_NORESERVE and wire it up in qemu_ram_mmap() David Hildenbrand
2021-04-28 13:37 ` [PATCH v7 09/15] util/mmap-alloc: Support RAM_NORESERVE via MAP_NORESERVE under Linux David Hildenbrand
2021-05-04 10:09 ` Daniel P. Berrangé
2021-05-04 10:21 ` David Hildenbrand
2021-05-04 10:32 ` Daniel P. Berrangé
2021-05-04 11:04 ` David Hildenbrand
2021-05-04 11:14 ` Daniel P. Berrangé
2021-05-04 11:28 ` David Hildenbrand
2021-04-28 13:37 ` [PATCH v7 10/15] hostmem: Wire up RAM_NORESERVE via "reserve" property David Hildenbrand
2021-05-04 9:58 ` Paolo Bonzini
2021-05-06 9:25 ` David Hildenbrand
2021-05-04 10:12 ` Daniel P. Berrangé
2021-05-04 11:08 ` David Hildenbrand
2021-05-04 11:18 ` Daniel P. Berrangé
2021-05-04 12:47 ` David Hildenbrand
2021-05-06 9:59 ` David Hildenbrand
2021-04-28 13:37 ` [PATCH v7 11/15] qmp: Clarify memory backend properties returned via query-memdev David Hildenbrand
2021-04-28 13:37 ` [PATCH v7 12/15] qmp: Include "share" property of memory backends David Hildenbrand
2021-04-28 13:37 ` [PATCH v7 13/15] hmp: Print "share" property of memory backends with "info memdev" David Hildenbrand
2021-04-28 13:37 ` [PATCH v7 14/15] qmp: Include "reserve" property of memory backends David Hildenbrand
2021-04-28 13:37 ` [PATCH v7 15/15] hmp: Print "reserve" property of memory backends with "info memdev" David Hildenbrand
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