Commit ec756e40 authored by Wanpeng Li's avatar Wanpeng Li Committed by Paolo Bonzini
Browse files

x86/kvm: Don't use pv tlb/ipi/sched_yield if on 1 vCPU 



Inspired by commit 3553ae56 (x86/kvm: Don't use pvqspinlock code if
only 1 vCPU), on a VM with only 1 vCPU, there is no need to enable
pv tlb/ipi/sched_yield and we can save the memory for __pv_cpu_mask.

Signed-off-by: default avatarWanpeng Li <wanpengli@tencent.com>
Message-Id: <1645171838-2855-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent ba1f77c5

arch/x86/kernel/kvm.c

+6 −3
Original line number Diff line number Diff line
@@ -462,19 +462,22 @@ static bool pv_tlb_flush_supported(void) 
{

	return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&

		!kvm_para_has_hint(KVM_HINTS_REALTIME) &&

		kvm_para_has_feature(KVM_FEATURE_STEAL_TIME));

		kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) &&

		(num_possible_cpus() != 1));

}



static bool pv_ipi_supported(void)

{

	return kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI);

	return (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI) &&

	       (num_possible_cpus() != 1));

}



static bool pv_sched_yield_supported(void)

{

	return (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) &&

		!kvm_para_has_hint(KVM_HINTS_REALTIME) &&

	    kvm_para_has_feature(KVM_FEATURE_STEAL_TIME));

	    kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) &&

	    (num_possible_cpus() != 1));

}



#define KVM_IPI_CLUSTER_SIZE	(2 * BITS_PER_LONG)