>>> On 10.04.18 at 09:58, <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> > --- > V6: > - correct an error from rebasing to staging in assembly part I have to admit that without digging out v5 I can't spot the change. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
