From: Christian Borntraeger <[email protected]> Some memslot updates dont affect the gmap implementation, e.g. setting/unsetting dirty tracking. Since a gmap update will cause tlb flushes and segment table invalidations we want to avoid that.
Signed-off-by: Christian Borntraeger <[email protected]> Signed-off-by: Cornelia Huck <[email protected]> --- arch/s390/kvm/kvm-s390.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 33161b4..f241e33 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -1007,6 +1007,16 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, { int rc; + /* If the basics of the memslot do not change, we do not want + * to update the gmap. Every update causes several unnecessary + * segment translation exceptions. This is usually handled just + * fine by the normal fault handler + gmap, but it will also + * cause faults on the prefix page of running guest CPUs. + */ + if (old->userspace_addr == mem->userspace_addr && + old->base_gfn * PAGE_SIZE == mem->guest_phys_addr && + old->npages * PAGE_SIZE == mem->memory_size) + return; rc = gmap_map_segment(kvm->arch.gmap, mem->userspace_addr, mem->guest_phys_addr, mem->memory_size); -- 1.7.12.4 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
