On Sat, Jan 21, 2023 at 02:07:35AM +0000, Kechen Lu wrote: > Date: Sat, 21 Jan 2023 02:07:35 +0000 > From: Kechen Lu <kechenl@xxxxxxxxxx> > Subject: [RFC PATCH v6 3/6] KVM: x86: Reject disabling of MWAIT > interception when not allowed > X-Mailer: git-send-email 2.34.1 > > From: Sean Christopherson <seanjc@xxxxxxxxxx> > > 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 nit: always-running? > APIC timer. > > Fixes: 4d5422cea3b6 ("KVM: X86: Provide a capability to disable MWAIT intercepts") > > Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> > Signed-off-by: Kechen Lu <kechenl@xxxxxxxxxx> > --- > arch/x86/kvm/x86.c | 20 +++++++++++++------- > 1 file changed, 13 insertions(+), 7 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 9a77b55142c6..60caa3fd40e5 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -4326,6 +4326,16 @@ 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_VALID_EXITS; > + > + 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) > { > @@ -4448,10 +4458,7 @@ 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: > if (!IS_ENABLED(CONFIG_KVM_SMM)) > @@ -6224,15 +6231,14 @@ 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; > > mutex_lock(&kvm->lock); > if (kvm->created_vcpus) > goto disable_exits_unlock; > > - 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 >