Hi Zhao, > -----Original Message----- > From: Zhao Liu <zhao1.liu@xxxxxxxxxxxxxxx> > Sent: Tuesday, January 31, 2023 4:12 AM > To: Kechen Lu <kechenl@xxxxxxxxxx> > Cc: kvm@xxxxxxxxxxxxxxx; seanjc@xxxxxxxxxx; pbonzini@xxxxxxxxxx; > zhi.wang.linux@xxxxxxxxx; chao.gao@xxxxxxxxx; shaoqin.huang@xxxxxxxxx; > vkuznets@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx > Subject: Re: [RFC PATCH v6 3/6] KVM: x86: Reject disabling of MWAIT > interception when not allowed > > External email: Use caution opening links or attachments > > > 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? Ack. Thanks. BR, Kechen > > > 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 > >