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2023-02-11util/userfaultfd: Support /dev/userfaultfdPeter Xu1-0/+32
Teach QEMU to use /dev/userfaultfd when it existed and fallback to the system call if either it's not there or doesn't have enough permission. Firstly, as long as the app has permission to access /dev/userfaultfd, it always have the ability to trap kernel faults which QEMU mostly wants. Meanwhile, in some context (e.g. containers) the userfaultfd syscall can be forbidden, so it can be the major way to use postcopy in a restricted environment with strict seccomp setup. Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Juan Quintela <quintela@redhat.com>
2023-02-06util/userfaultfd: Add uffd_open()Peter Xu1-2/+11
Add a helper to create the uffd handle. Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> Reviewed-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Juan Quintela <quintela@redhat.com>
2021-02-08migration: introduce UFFD-WP low-level interface helpersAndrey Gruzdev1-0/+345
Glue code to the userfaultfd kernel implementation. Querying feature support, createing file descriptor, feature control, memory region registration, IOCTLs on registered registered regions. Signed-off-by: Andrey Gruzdev <andrey.gruzdev@virtuozzo.com> Reviewed-by: Peter Xu <peterx@redhat.com> Message-Id: <20210129101407.103458-3-andrey.gruzdev@virtuozzo.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Fixed up range.start casting for 32bit