2022-02-25 12:53:15

by Wanpeng Li

[permalink] [raw]
Subject: [PATCH] x86/kvm: Don't use PV TLB/yield when mwait is advertised

From: Wanpeng Li <[email protected]>

MWAIT is advertised in host is not overcommitted scenario, however, PV
TLB/sched yield should be enabled in host overcommitted scenario. Let's
add the MWAIT checking when enabling PV TLB/sched yield.

Signed-off-by: Wanpeng Li <[email protected]>
---
arch/x86/kernel/kvm.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index f734e3b0cfec..491e1d9ca750 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -463,6 +463,7 @@ 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) &&
+ !boot_cpu_has(X86_FEATURE_MWAIT) &&
(num_possible_cpus() != 1));
}

@@ -477,6 +478,7 @@ 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) &&
+ !boot_cpu_has(X86_FEATURE_MWAIT) &&
(num_possible_cpus() != 1));
}

--
2.25.1