hostmem-memfd: add checks before adding hostmem-memfd & properties

Run some memfd-related checks before registering hostmem-memfd &
various properties. This will help libvirt to figure out what the host
is supposed to be capable of.

qemu_memfd_check() is changed to a less optimized version, since it is
used with various flags, it no longer caches the result.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20180906161415.8543-1-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 6 insertions, 29 deletions

diff --git a/util/memfd.c b/util/memfd.c
index 6287946b61..8debd0d037 100644
--- a/util/memfd.c
+++ b/util/memfd.c
@@ -45,22 +45,6 @@ static int memfd_create(const char *name, unsigned int flags)
 }
 #endif
 
-#ifndef MFD_CLOEXEC
-#define MFD_CLOEXEC 0x0001U
-#endif
-
-#ifndef MFD_ALLOW_SEALING
-#define MFD_ALLOW_SEALING 0x0002U
-#endif
-
-#ifndef MFD_HUGETLB
-#define MFD_HUGETLB 0x0004U
-#endif
-
-#ifndef MFD_HUGE_SHIFT
-#define MFD_HUGE_SHIFT 26
-#endif
-
 int qemu_memfd_create(const char *name, size_t size, bool hugetlb,
                       uint64_t hugetlbsize, unsigned int seals, Error **errp)
 {
@@ -201,23 +185,16 @@ bool qemu_memfd_alloc_check(void)
  *
  * Check if host supports memfd.
  */
-bool qemu_memfd_check(void)
+bool qemu_memfd_check(unsigned int flags)
 {
 #ifdef CONFIG_LINUX
-    static int memfd_check = MEMFD_TODO;
+    int mfd = memfd_create("test", flags);
 
-    if (memfd_check == MEMFD_TODO) {
-        int mfd = memfd_create("test", 0);
-        if (mfd >= 0) {
-            memfd_check = MEMFD_OK;
-            close(mfd);
-        } else {
-            memfd_check = MEMFD_KO;
-        }
+    if (mfd >= 0) {
+        close(mfd);
+        return true;
     }
+#endif
 
-    return memfd_check == MEMFD_OK;
-#else
     return false;
-#endif
 }