On Wed, Feb 12, 2025 at 05:39:17PM +0300, Daniil Tatianin wrote:
> This will be used in the following commits to make it possible to only
> lock memory on fault instead of right away.
>
> Signed-off-by: Daniil Tatianin <d-tatia...@yandex-team.ru>
> ---
> include/system/os-posix.h | 2 +-
> include/system/os-win32.h | 3 ++-
> meson.build | 6 ++++++
> migration/postcopy-ram.c | 2 +-
> os-posix.c | 14 ++++++++++++--
> system/vl.c | 2 +-
> 6 files changed, 23 insertions(+), 6 deletions(-)
>
> diff --git a/include/system/os-posix.h b/include/system/os-posix.h
> index b881ac6c6f..ce5b3bccf8 100644
> --- a/include/system/os-posix.h
> +++ b/include/system/os-posix.h
> @@ -53,7 +53,7 @@ bool os_set_runas(const char *user_id);
> void os_set_chroot(const char *path);
> void os_setup_limits(void);
> void os_setup_post(void);
> -int os_mlock(void);
> +int os_mlock(bool on_fault);
>
> /**
> * qemu_alloc_stack:
> diff --git a/include/system/os-win32.h b/include/system/os-win32.h
> index b82a5d3ad9..cd61d69e10 100644
> --- a/include/system/os-win32.h
> +++ b/include/system/os-win32.h
> @@ -123,8 +123,9 @@ static inline bool is_daemonized(void)
> return false;
> }
>
> -static inline int os_mlock(void)
> +static inline int os_mlock(bool on_fault)
> {
> + (void)on_fault;
> return -ENOSYS;
> }
>
> diff --git a/meson.build b/meson.build
> index 18cf9e2913..59953cbe6b 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -2885,6 +2885,12 @@ config_host_data.set('HAVE_MLOCKALL',
> cc.links(gnu_source_prefix + '''
> return mlockall(MCL_FUTURE);
> }'''))
>
> +config_host_data.set('HAVE_MLOCK_ONFAULT', cc.links(gnu_source_prefix + '''
> + #include <sys/mman.h>
> + int main(void) {
> + return mlockall(MCL_FUTURE | MCL_ONFAULT);
> + }'''))
> +
> have_l2tpv3 = false
> if get_option('l2tpv3').allowed() and have_system
> have_l2tpv3 = cc.has_type('struct mmsghdr',
> diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
> index 6a6da6ba7f..fc4d8a10df 100644
> --- a/migration/postcopy-ram.c
> +++ b/migration/postcopy-ram.c
> @@ -652,7 +652,7 @@ int postcopy_ram_incoming_cleanup(MigrationIncomingState
> *mis)
> }
>
> if (enable_mlock) {
> - if (os_mlock() < 0) {
> + if (os_mlock(false) < 0) {
> error_report("mlock: %s", strerror(errno));
> /*
> * It doesn't feel right to fail at this point, we have a valid
> diff --git a/os-posix.c b/os-posix.c
> index 9cce55ff2f..17b144c0a2 100644
> --- a/os-posix.c
> +++ b/os-posix.c
> @@ -327,18 +327,28 @@ void os_set_line_buffering(void)
> setvbuf(stdout, NULL, _IOLBF, 0);
> }
>
> -int os_mlock(void)
> +int os_mlock(bool on_fault)
> {
> #ifdef HAVE_MLOCKALL
> int ret = 0;
> + int flags = MCL_CURRENT | MCL_FUTURE;
>
> - ret = mlockall(MCL_CURRENT | MCL_FUTURE);
> +#ifdef HAVE_MLOCK_ONFAULT
> + if (on_fault) {
> + flags |= MCL_ONFAULT;
> + }
> +#else
> + (void)on_fault;
> +#endif
IIUC we should fail this when not supported.
Would you mind I squash this in?
diff --git a/os-posix.c b/os-posix.c
index 17b144c0a2..52925c23d3 100644
--- a/os-posix.c
+++ b/os-posix.c
@@ -333,13 +333,14 @@ int os_mlock(bool on_fault)
int ret = 0;
int flags = MCL_CURRENT | MCL_FUTURE;
-#ifdef HAVE_MLOCK_ONFAULT
if (on_fault) {
+#ifdef HAVE_MLOCK_ONFAULT
flags |= MCL_ONFAULT;
- }
#else
- (void)on_fault;
+ error_report("mlockall: on_fault not supported");
+ return -EINVAL;
#endif
+ }
ret = mlockall(flags);
if (ret < 0) {
> +
> + ret = mlockall(flags);
> if (ret < 0) {
> error_report("mlockall: %s", strerror(errno));
> }
>
> return ret;
> #else
> + (void)on_fault;
> return -ENOSYS;
> #endif
> }
> diff --git a/system/vl.c b/system/vl.c
> index 9c6942c6cf..e94fc7ea35 100644
> --- a/system/vl.c
> +++ b/system/vl.c
> @@ -797,7 +797,7 @@ static QemuOptsList qemu_run_with_opts = {
> static void realtime_init(void)
> {
> if (enable_mlock) {
> - if (os_mlock() < 0) {
> + if (os_mlock(false) < 0) {
> error_report("locking memory failed");
> exit(1);
> }
> --
> 2.34.1
>
--
Peter Xu
