diff options
| author | Stefano Garzarella <sgarzare@redhat.com> | 2024-06-18 12:05:19 +0200 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2024-07-03 18:14:06 -0400 |
| commit | 4e647fa08586a5ada74cf6d3ae1cdf3a027202cb (patch) | |
| tree | 396296ac8c5ddfb099d088300a9a99d59a3f5b7c /qapi/qom.json | |
| parent | 5ab04420c3de11ae4a573b08b53584a2a0c5dd00 (diff) | |
hostmem: add a new memory backend based on POSIX shm_open()
shm_open() creates and opens a new POSIX shared memory object.
A POSIX shared memory object allows creating memory backend with an
associated file descriptor that can be shared with external processes
(e.g. vhost-user).
The new `memory-backend-shm` can be used as an alternative when
`memory-backend-memfd` is not available (Linux only), since shm_open()
should be provided by any POSIX-compliant operating system.
This backend mimics memfd, allocating memory that is practically
anonymous. In theory shm_open() requires a name, but this is allocated
for a short time interval and shm_unlink() is called right after
shm_open(). After that, only fd is shared with external processes
(e.g., vhost-user) as if it were associated with anonymous memory.
In the future we may also allow the user to specify the name to be
passed to shm_open(), but for now we keep the backend simple, mimicking
anonymous memory such as memfd.
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com> (QAPI schema)
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20240618100519.145853-1-sgarzare@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'qapi/qom.json')
| -rw-r--r-- | qapi/qom.json | 23 |
1 files changed, 21 insertions, 2 deletions
diff --git a/qapi/qom.json b/qapi/qom.json index 9b8f6a7ab5..92b0fea76c 100644 --- a/qapi/qom.json +++ b/qapi/qom.json @@ -601,8 +601,8 @@ # # @share: if false, the memory is private to QEMU; if true, it is # shared (default false for backends memory-backend-file and -# memory-backend-ram, true for backends memory-backend-epc and -# memory-backend-memfd) +# memory-backend-ram, true for backends memory-backend-epc, +# memory-backend-memfd, and memory-backend-shm) # # @reserve: if true, reserve swap space (or huge pages) if applicable # (default: true) (since 6.1) @@ -722,6 +722,21 @@ '*seal': 'bool' } } ## +# @MemoryBackendShmProperties: +# +# Properties for memory-backend-shm objects. +# +# This memory backend supports only shared memory, which is the +# default. +# +# Since: 9.1 +## +{ 'struct': 'MemoryBackendShmProperties', + 'base': 'MemoryBackendProperties', + 'data': { }, + 'if': 'CONFIG_POSIX' } + +## # @MemoryBackendEpcProperties: # # Properties for memory-backend-epc objects. @@ -1049,6 +1064,8 @@ { 'name': 'memory-backend-memfd', 'if': 'CONFIG_LINUX' }, 'memory-backend-ram', + { 'name': 'memory-backend-shm', + 'if': 'CONFIG_POSIX' }, 'pef-guest', { 'name': 'pr-manager-helper', 'if': 'CONFIG_LINUX' }, @@ -1121,6 +1138,8 @@ 'memory-backend-memfd': { 'type': 'MemoryBackendMemfdProperties', 'if': 'CONFIG_LINUX' }, 'memory-backend-ram': 'MemoryBackendProperties', + 'memory-backend-shm': { 'type': 'MemoryBackendShmProperties', + 'if': 'CONFIG_POSIX' }, 'pr-manager-helper': { 'type': 'PrManagerHelperProperties', 'if': 'CONFIG_LINUX' }, 'qtest': 'QtestProperties', |