xen/pvh/mmu: Use PV TLB instead of native.

We also optimize one - the TLB flush. The native operation would
needlessly IPI offline VCPUs causing extra wakeups. Using the
Xen one avoids that and lets the hypervisor determine which
VCPU needs the TLB flush.
Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

arch/x86/xen/mmu.c

@@ -2222,6 +2222,15 @@ static const struct pv_mmu_ops xen_mmu_ops __initconst = {
 void __init xen_init_mmu_ops(void)
 {
 	x86_init.paging.pagetable_init = xen_pagetable_init;
+
+	/* Optimization - we can use the HVM one but it has no idea which
+	 * VCPUs are descheduled - which means that it will needlessly IPI
+	 * them. Xen knows so let it do the job.
+	 */
+	if (xen_feature(XENFEAT_auto_translated_physmap)) {
+		pv_mmu_ops.flush_tlb_others = xen_flush_tlb_others;
+		return;
+	}
 	pv_mmu_ops = xen_mmu_ops;
 
 	memset(dummy_mapping, 0xff, PAGE_SIZE);