>>> On 12.04.18 at 20:09, <jgr...@suse.com> wrote: > For mitigation of Meltdown the current L4 page table is copied to the > cpu local root page table each time a 64 bit pv guest is entered. > > Copying can be avoided in cases where the guest L4 page table hasn't > been modified while running the hypervisor, e.g. when handling > interrupts or any hypercall not modifying the L4 page table or %cr3. > > So add a per-cpu flag indicating whether the copying should be > performed and set that flag only when loading a new %cr3 or modifying > the L4 page table. This includes synchronization of the cpu local > root page table with other cpus, so add a special synchronization flag > for that case. > > A simple performance check (compiling the hypervisor via "make -j 4") > in dom0 with 4 vcpus shows a significant improvement: > > - real time drops from 112 seconds to 103 seconds > - system time drops from 142 seconds to 131 seconds > > Signed-off-by: Juergen Gross <jgr...@suse.com> > Reviewed-by: Jan Beulich <jbeul...@suse.com> > --- > V7: > - add missing flag setting in shadow code
This now needs an ack from Tim (now Cc-ed). Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
