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memfd: fix vhost-user-test on non-memfd capable host 

On RHEL7, memfd is not supported, and vhost-user-test fails:
TEST: tests/vhost-user-test... (pid=10248)
  /x86_64/vhost-user/migrate:
  qemu-system-x86_64: -object memory-backend-memfd,id=mem,size=2M,: failed to create memfd
FAIL

There is a qemu_memfd_check() to prevent running memfd path, but it
also checks for fallback implementation. Let's specialize
qemu_memfd_check() to check memfd only, while qemu_memfd_alloc_check()
checks for the qemu_memfd_alloc() API.

Reported-by: Miroslav Rezanina <mrezanin@redhat.com>
Tested-by: Miroslav Rezanina <mrezanin@redhat.com>
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20180328121804.16203-1-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
This commit is contained in:
Marc-André Lureau 2018-03-28 14:18:04 +02:00 committed by Paolo Bonzini
parent 053e45d2f3
commit 648abbfbaa
3 changed files with 35 additions and 2 deletions
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2
hw/virtio/vhost.c
View File

@ -1223,7 +1223,7 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
if (!(hdev->features & (0x1ULL << VHOST_F_LOG_ALL))) {
error_setg(&hdev->migration_blocker,
"Migration disabled: vhost lacks VHOST_F_LOG_ALL feature.");
} else if (vhost_dev_log_is_shared(hdev) && !qemu_memfd_check()) {
} else if (vhost_dev_log_is_shared(hdev) && !qemu_memfd_alloc_check()) {
error_setg(&hdev->migration_blocker,
"Migration disabled: failed to allocate shared memory");
}

1
include/qemu/memfd.h
View File

@ -18,6 +18,7 @@
int qemu_memfd_create(const char *name, size_t size, bool hugetlb,
uint64_t hugetlbsize, unsigned int seals, Error **errp);
bool qemu_memfd_alloc_check(void);
void *qemu_memfd_alloc(const char *name, size_t size, unsigned int seals,
int *fd, Error **errp);
void qemu_memfd_free(void *ptr, size_t size, int fd);

34
util/memfd.c
View File

@ -173,7 +173,13 @@ enum {
MEMFD_TODO
};
bool qemu_memfd_check(void)
/**
* qemu_memfd_alloc_check():
*
* Check if qemu_memfd_alloc() can allocate, including using a
* fallback implementation when host doesn't support memfd.
*/
bool qemu_memfd_alloc_check(void)
{
static int memfd_check = MEMFD_TODO;
@ -188,3 +194,29 @@ bool qemu_memfd_check(void)
return memfd_check == MEMFD_OK;
}
/**
* qemu_memfd_check():
*
* Check if host supports memfd.
*/
bool qemu_memfd_check(void)
{
#ifdef CONFIG_LINUX
static int memfd_check = MEMFD_TODO;
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;
}
}
return memfd_check == MEMFD_OK;
#else
return false;
#endif
}