Commit 648abbfb authored by Marc-André Lureau's avatar Marc-André Lureau Committed by Paolo Bonzini
Browse files

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: default avatarMiroslav Rezanina <mrezanin@redhat.com>
Tested-by: default avatarMiroslav Rezanina <mrezanin@redhat.com>
Signed-off-by: default avatarMarc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20180328121804.16203-1-marcandre.lureau@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarMarc-André Lureau <marcandre.lureau@redhat.com>
parent 053e45d2

hw/virtio/vhost.c

+1 −1
Original line number Diff line number Diff line
@@ -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");

        }

include/qemu/memfd.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

util/memfd.c

+33 −1
Original line number Diff line number Diff line
@@ -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

}