Messages in this thread Patch in this message | | | Date | Thu, 29 Jun 2023 13:50:40 -0700 | Subject | [PATCH v2 6/6] mm: userfaultfd: add basic documentation for UFFDIO_POISON | From | Axel Rasmussen <> |
| |
Just describe the feature at a really basic level.
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> --- Documentation/admin-guide/mm/userfaultfd.rst | 15 +++++++++++++++ 1 file changed, 15 insertions(+)
diff --git a/Documentation/admin-guide/mm/userfaultfd.rst b/Documentation/admin-guide/mm/userfaultfd.rst index 7c304e432205..b19053436369 100644 --- a/Documentation/admin-guide/mm/userfaultfd.rst +++ b/Documentation/admin-guide/mm/userfaultfd.rst @@ -244,6 +244,21 @@ write-protected (so future writes will also result in a WP fault). These ioctls support a mode flag (``UFFDIO_COPY_MODE_WP`` or ``UFFDIO_CONTINUE_MODE_WP`` respectively) to configure the mapping this way. +Memory Poisioning Emulation +--------------------------- + +In response to a fault (either missing or minor), an action userspace can +take to "resolve" it is to issue a ``UFFDIO_POISON``. This will cause any +future faulters to either get a SIGBUS, or in KVM's case the guest will +receive an MCE as if there were hardware memory poisoning. + +This is used to emulate hardware memory poisoning. Imagine a VM running on a +machine which experiences a real hardware memory error. Later, we live migrate +the VM to another physical machine. Since we want the migration to be +transparent to the guest, we want that same address range to act as if it was +still poisoned, even though it's on a new physical host which ostentisbly +doesn't have a memory error in the exact same spot. + QEMU/KVM ======== -- 2.41.0.255.g8b1d071c50-goog
| |