From: Wanpeng Li wanpengli@tencent.com
[ Upstream commit ec756e40e271866f951d77c5e923d8deb6002b15 ]
Inspired by commit 3553ae5690a (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: Wanpeng Li wanpengli@tencent.com Message-Id: 1645171838-2855-1-git-send-email-wanpengli@tencent.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/kernel/kvm.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index b656456c3a94..811c7aaf23aa 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -457,19 +457,22 @@ 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)