On 07.01.2021 14:23, Tamas K Lengyel wrote: > Several lock-order violations have been encountered while attempting to fork > VMs with nestedhvm=1 set. This patch resolves the issues. > > The order violations stems from a call to p2m_flush_nestedp2m being performed > whenever the hostp2m changes. This functions always takes the p2m lock for the > nested_p2m. However, with sharing the p2m locks always have to be taken before > the sharing lock. To resolve this issue we avoid taking the sharing lock where > possible (and was actually unecessary to begin with). But we also make > p2m_flush_nestedp2m aware that the p2m lock may have already been taken and > preemptively take all nested_p2m locks before unsharing a page where taking > the > sharing lock is necessary. > > Signed-off-by: Tamas K Lengyel <[email protected]>
Acked-by: Jan Beulich <[email protected]>
