include: move qemu_msync() to osdep

The implementation depends on the OS. (and longer-term goal is to move
cutils to a common subproject)

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20220420132624.2439741-21-marcandre.lureau@redhat.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index c471c5bc9f..161f112325 100644
--- a/util/oslib-posix.c
+++ b/util/oslib-posix.c
@@ -950,3 +950,21 @@ int fcntl_setfl(int fd, int flag)
     }
     return 0;
 }
+
+int qemu_msync(void *addr, size_t length, int fd)
+{
+    size_t align_mask = ~(qemu_real_host_page_size() - 1);
+
+    /**
+     * There are no strict reqs as per the length of mapping
+     * to be synced. Still the length needs to follow the address
+     * alignment changes. Additionally - round the size to the multiple
+     * of PAGE_SIZE
+     */
+    length += ((uintptr_t)addr & (qemu_real_host_page_size() - 1));
+    length = (length + ~align_mask) & align_mask;
+
+    addr = (void *)((uintptr_t)addr & align_mask);
+
+    return msync(addr, length, MS_SYNC);
+}