diff mbox series

[RFC,v6,3/6] KVM: x86: Reject disabling of MWAIT interception when not allowed

Message ID 20230121020738.2973-4-kechenl@nvidia.com (mailing list archive)
State New, archived
Headers show
Series KVM: x86: add per-vCPU exits disable capability | expand

Commit Message

Kechen Lu Jan. 21, 2023, 2:07 a.m. UTC 
From: Sean Christopherson <seanjc@google.com>

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 <seanjc@google.com>
Signed-off-by: Kechen Lu <kechenl@nvidia.com>
---
 arch/x86/kvm/x86.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

Comments

Zhao Liu Jan. 31, 2023, 12:11 p.m. UTC | #1 
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@nvidia.com>
> 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@google.com>
> 
> 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@google.com>
> Signed-off-by: Kechen Lu <kechenl@nvidia.com>
> ---
>  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
>
Kechen Lu Feb. 1, 2023, 12:43 a.m. UTC | #2 
Hi Zhao,

> -----Original Message-----
> From: Zhao Liu <zhao1.liu@linux.intel.com>
> Sent: Tuesday, January 31, 2023 4:12 AM
> To: Kechen Lu <kechenl@nvidia.com>
> Cc: kvm@vger.kernel.org; seanjc@google.com; pbonzini@redhat.com;
> zhi.wang.linux@gmail.com; chao.gao@intel.com; shaoqin.huang@intel.com;
> vkuznets@redhat.com; linux-kernel@vger.kernel.org
> 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@nvidia.com>
> > 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@google.com>
> >
> > 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@google.com>
> > Signed-off-by: Kechen Lu <kechenl@nvidia.com>
> > ---
> >  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
> >
diff mbox series

Patch

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;