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

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Inspired by commit 3553ae5690 (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>
This commit is contained in:
Wanpeng Li 2022-02-18 00:10:38 -08:00 committed by Paolo Bonzini
parent ba1f77c546
commit ec756e40e2
1 changed files with 6 additions and 3 deletions
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9
arch/x86/kernel/kvm.c
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@ -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)