From 10798eb3fc1fe7f7240acd0f2667a6519ae445c5 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Mon, 10 Jan 2022 12:29:28 -0800 Subject: [PATCH] KVM: x86: Reject disabling of MWAIT interception when not allowed Reject KVM_CAP_X86_DISABLE_EXITS if userspace attempts to disable MWAIT exits and KVM previously reported (via KVM_CHECK_EXTENSION) that MWAIT is not allowed in guest, e.g. because it's not supported or the CPU doesn't have an aways-running APIC timer. Fixes: 4d5422cea3b6 ("KVM: X86: Provide a capability to disable MWAIT intercepts") Signed-off-by: Sean Christopherson --- arch/x86/kvm/x86.c | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c194a8cbd25f..9de22dceb49b 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4087,6 +4087,17 @@ static inline bool kvm_can_mwait_in_guest(void) boot_cpu_has(X86_FEATURE_ARAT); } +static u64 kvm_get_allowed_disable_exits(void) +{ + u64 r = KVM_X86_DISABLE_EXITS_HLT | KVM_X86_DISABLE_EXITS_PAUSE | + KVM_X86_DISABLE_EXITS_CSTATE; + + if(kvm_can_mwait_in_guest()) + r |= KVM_X86_DISABLE_EXITS_MWAIT; + + return r; +} + static int kvm_ioctl_get_supported_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 __user *cpuid_arg) { @@ -4202,10 +4213,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) r = KVM_CLOCK_VALID_FLAGS; break; case KVM_CAP_X86_DISABLE_EXITS: - r |= KVM_X86_DISABLE_EXITS_HLT | KVM_X86_DISABLE_EXITS_PAUSE | - KVM_X86_DISABLE_EXITS_CSTATE; - if(kvm_can_mwait_in_guest()) - r |= KVM_X86_DISABLE_EXITS_MWAIT; + r |= kvm_get_allowed_disable_exits(); break; case KVM_CAP_X86_SMM: /* SMBASE is usually relocated above 1M on modern chipsets, @@ -5779,11 +5787,10 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, break; case KVM_CAP_X86_DISABLE_EXITS: r = -EINVAL; - if (cap->args[0] & ~KVM_X86_DISABLE_VALID_EXITS) + if (cap->args[0] & ~kvm_get_allowed_disable_exits()) break; - if ((cap->args[0] & KVM_X86_DISABLE_EXITS_MWAIT) && - kvm_can_mwait_in_guest()) + if (cap->args[0] & KVM_X86_DISABLE_EXITS_MWAIT) kvm->arch.mwait_in_guest = true; if (cap->args[0] & KVM_X86_DISABLE_EXITS_HLT) kvm->arch.hlt_in_guest = true; -- 2.34.1.575.g55b058a8bb-goog