From 64b38bd1906bb62a040b4e91815e56005db4784d Mon Sep 17 00:00:00 2001 From: Thadeu Lima de Souza Cascardo Date: Fri, 31 Jan 2020 12:56:55 -0300 Subject: [PATCH] x86/kvm: do not setup pv tlb flush when not paravirtualized kvm_setup_pv_tlb_flush will waste memory and print a misguiding message when KVM paravirtualization is not available. Intel SDM says that the when cpuid is used with EAX higher than the maximum supported value for basic of extended function, the data for the highest supported basic function will be returned. So, in some systems, kvm_arch_para_features will return bogus data, causing kvm_setup_pv_tlb_flush to detect support for pv tlb flush. Testing for kvm_para_available will work as it checks for the hypervisor signature. Besides, when the "nopv" command line parameter is used, it should not continue as well, as kvm_guest_init will no be called in that case. Signed-off-by: Thadeu Lima de Souza Cascardo Signed-off-by: Paolo Bonzini --- arch/x86/kernel/kvm.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index 81045aabb6f4..d817f255aed8 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -736,6 +736,9 @@ static __init int kvm_setup_pv_tlb_flush(void) { int cpu; + if (!kvm_para_available() || nopv) + return 0; + if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) && !kvm_para_has_hint(KVM_HINTS_REALTIME) && kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {