Add support for the memfd_create syscall. If the host does not have the
libc wrapper, translate to a direct syscall with NC-macro.
Buglink: https://bugs.launchpad.net/qemu/+bug/1734792
Signed-off-by: Shu-Chun Weng <scw@google.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20190819180947.180725-1-scw@google.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
This gives more information about the failure.
Additionally 'ENOSYS' returned for a non-Linux platforms instead of
'errno', which is not initilaized in this case.
Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20190311135850.6537-5-i.maximets@samsung.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
qemu_memfd_create() prints the value of 'errno' which is not
set in this case.
Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20190311135850.6537-4-i.maximets@samsung.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
QEMU always sets this flag unconditionally. We need to
check if it's supported.
Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20190311135850.6537-3-i.maximets@samsung.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
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>
The qemu_memfd_alloc_check() routine allocates the fd variable on stack.
This variable is initialized inside the qemu_memfd_alloc() function.
There are several cases when *fd will be left unintialized which can
lead to the unexpected close() in the qemu_memfd_free() call.
Set file descriptor to -1 before calling the qemu_memfd_alloc routine.
Signed-off-by: Dima Stepanov <dimastep@yandex-team.ru>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Coverity complains about qemu_memfd_create() (CID 1385858) because
we calculate a bit position htsize which could be up to 63, but
then use it in "1 << htsize" which is a 32-bit integer calculation
and could push the 1 off the top of the value.
Silence the complaint bu using "1ULL"; this isn't a bug in
practice since a hugetlbsize of 4GB is not very plausible.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20180515172729.24564-1-peter.maydell@linaro.org>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Linux commit 749df87bd7bee5a79cef073f5d032ddb2b211de8 (v4.14-rc1)
added a new flag MFD_HUGETLB to memfd_create() that specify the file
to be created resides in the hugetlbfs filesystem. This is the
generic hugetlbfs filesystem not associated with any specific mount
point.
hugetlbfs does not support sealing operations in v4.14, therefore
specifying MFD_ALLOW_SEALING with MFD_HUGETLB will result in EINVAL.
However, I added sealing support in "[PATCH v3 0/9] memfd: add sealing
to hugetlb-backed memory" series, queued in -mm tree for v4.16.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20180201132757.23063-3-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This will allow callers to silence error report when the call is
allowed to failed.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20180201132757.23063-2-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add a function to only create a memfd, without mmap. The function is
used in the following memory backend.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20171023141815.17709-2-marcandre.lureau@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Recent glibc added memfd_create in sys/mman.h. This conflicts with
the definition in util/memfd.c:
/builddir/build/BUILD/qemu-2.11.0-rc1/util/memfd.c:40:12: error: static declaration of memfd_create follows non-static declaration
Fix the configure test, and remove the sys/memfd.h inclusion since the
file actually does not exist---it is a typo in the memfd_create(2) man
page.
Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
qemu/osdep.h checks whether MAP_ANONYMOUS is defined, but this check
is bogus without a previous inclusion of sys/mman.h. Include it in
sysemu/os-posix.h and remove it from everywhere else.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Remove glib.h includes, as it is provided by osdep.h.
This commit was created with scripts/clean-includes.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Tested-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Thibaut Collet <thibaut.collet@6wind.com>
Add an open/unlink/mmap fallback for system that do not support
memfd (only available since 3.17, ~1y ago).
This patch may require additional SELinux policies to work for enforced
systems, but should fail gracefully in this case.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Thibaut Collet <thibaut.collet@6wind.com>
Add qemu_memfd_alloc/free() helpers.
The function helps to allocate and seal shared memory.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Thibaut Collet <thibaut.collet@6wind.com>
Implement memfd_create() fallback if not available in system libc.
memfd_create() is still not included in glibc today, atlhough it's been
available since Linux 3.17 in Oct 2014.
memfd has numerous advantages over traditional shm/mmap for ipc memory
sharing with fd handler, which we are going to make use of for
vhost-user logging memory in following patches.
The next patches are going to introduce helpers to use best practices of
memfd usage and provide some compatibility fallback. memfd.c is thus
temporarily useless and eventually empty if memfd_create() is provided
by the system.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Thibaut Collet <thibaut.collet@6wind.com>
