* [PATCH] KVM: nVMX: Check that HLT activity state is supported
@ 2019-08-13 13:13 Nikita Leshenko
2019-08-13 14:35 ` Sean Christopherson
0 siblings, 1 reply; 3+ messages in thread
From: Nikita Leshenko @ 2019-08-13 13:13 UTC (permalink / raw)
To: kvm; +Cc: Nikita Leshenko, Liran Alon, Joao Martins
Fail VM entry if GUEST_ACTIVITY_HLT is unsupported. According to "SDM A.6 -
Miscellaneous Data", VM entry should fail if the HLT activity is not marked as
supported on IA32_VMX_MISC MSR.
Usermode might disable GUEST_ACTIVITY_HLT support in the vCPU with
vmx_restore_vmx_misc(). Before this commit VM entries would have succeeded
anyway.
Reviewed-by: Liran Alon <liran.alon@oracle.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Nikita Leshenko <nikita.leshchenko@oracle.com>
---
arch/x86/kvm/vmx/nested.c | 16 ++++++++++++----
arch/x86/kvm/vmx/nested.h | 5 +++++
2 files changed, 17 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 46af3a5e9209..3165e2f7992f 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2656,11 +2656,19 @@ static int nested_vmx_check_vmcs_link_ptr(struct kvm_vcpu *vcpu,
/*
* Checks related to Guest Non-register State
*/
-static int nested_check_guest_non_reg_state(struct vmcs12 *vmcs12)
+static int nested_check_guest_non_reg_state(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
{
- if (vmcs12->guest_activity_state != GUEST_ACTIVITY_ACTIVE &&
- vmcs12->guest_activity_state != GUEST_ACTIVITY_HLT)
+ switch (vmcs12->guest_activity_state) {
+ case GUEST_ACTIVITY_ACTIVE:
+ /* Always supported */
+ break;
+ case GUEST_ACTIVITY_HLT:
+ if (!nested_cpu_has_activity_state_hlt(vcpu))
+ return -EINVAL;
+ break;
+ default:
return -EINVAL;
+ }
return 0;
}
@@ -2710,7 +2718,7 @@ static int nested_vmx_check_guest_state(struct kvm_vcpu *vcpu,
(vmcs12->guest_bndcfgs & MSR_IA32_BNDCFGS_RSVD)))
return -EINVAL;
- if (nested_check_guest_non_reg_state(vmcs12))
+ if (nested_check_guest_non_reg_state(vcpu, vmcs12))
return -EINVAL;
return 0;
diff --git a/arch/x86/kvm/vmx/nested.h b/arch/x86/kvm/vmx/nested.h
index e847ff1019a2..4a294d3ff820 100644
--- a/arch/x86/kvm/vmx/nested.h
+++ b/arch/x86/kvm/vmx/nested.h
@@ -123,6 +123,11 @@ static inline bool nested_cpu_has_zero_length_injection(struct kvm_vcpu *vcpu)
return to_vmx(vcpu)->nested.msrs.misc_low & VMX_MISC_ZERO_LEN_INS;
}
+static inline bool nested_cpu_has_activity_state_hlt(struct kvm_vcpu *vcpu)
+{
+ return to_vmx(vcpu)->nested.msrs.misc_low & VMX_MISC_ACTIVITY_HLT;
+}
+
static inline bool nested_cpu_supports_monitor_trap_flag(struct kvm_vcpu *vcpu)
{
return to_vmx(vcpu)->nested.msrs.procbased_ctls_high &
--
2.20.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] KVM: nVMX: Check that HLT activity state is supported
2019-08-13 13:13 [PATCH] KVM: nVMX: Check that HLT activity state is supported Nikita Leshenko
@ 2019-08-13 14:35 ` Sean Christopherson
2019-08-14 6:59 ` Nikita Leshenko
0 siblings, 1 reply; 3+ messages in thread
From: Sean Christopherson @ 2019-08-13 14:35 UTC (permalink / raw)
To: Nikita Leshenko; +Cc: kvm, Liran Alon, Joao Martins
On Tue, Aug 13, 2019 at 04:13:03PM +0300, Nikita Leshenko wrote:
> Fail VM entry if GUEST_ACTIVITY_HLT is unsupported. According to "SDM A.6 -
> Miscellaneous Data", VM entry should fail if the HLT activity is not marked as
> supported on IA32_VMX_MISC MSR.
>
> Usermode might disable GUEST_ACTIVITY_HLT support in the vCPU with
> vmx_restore_vmx_misc(). Before this commit VM entries would have succeeded
> anyway.
Is there a use case for disabling GUEST_ACTIVITY_HLT? Or can we simply
disallow writes to IA32_VMX_MISC that disable GUEST_ACTIVITY_HLT?
To disable GUEST_ACTIVITY_HLT, userspace also has to make
CPU_BASED_HLT_EXITING a "must be 1" control, otherwise KVM will be
presenting a bogus model to L1.
The bad model is visible to L1 if CPU_BASED_HLT_EXITING is set by L0,
i.e. KVM is running without kvm_hlt_in_guest(), and cleared by L1. In
that case, a HLT from L2 will be handled in L0. L0 will set the state to
KVM_MP_STATE_HALTED and report to L1 (on a nested VM-Exit, e.g. INTR),
that the activity state is GUEST_ACTIVITY_HLT, which from L1's perspective
doesn't exist.
> Reviewed-by: Liran Alon <liran.alon@oracle.com>
> Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
> Signed-off-by: Nikita Leshenko <nikita.leshchenko@oracle.com>
> ---
> arch/x86/kvm/vmx/nested.c | 16 ++++++++++++----
> arch/x86/kvm/vmx/nested.h | 5 +++++
> 2 files changed, 17 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index 46af3a5e9209..3165e2f7992f 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -2656,11 +2656,19 @@ static int nested_vmx_check_vmcs_link_ptr(struct kvm_vcpu *vcpu,
> /*
> * Checks related to Guest Non-register State
> */
> -static int nested_check_guest_non_reg_state(struct vmcs12 *vmcs12)
> +static int nested_check_guest_non_reg_state(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
> {
> - if (vmcs12->guest_activity_state != GUEST_ACTIVITY_ACTIVE &&
> - vmcs12->guest_activity_state != GUEST_ACTIVITY_HLT)
> + switch (vmcs12->guest_activity_state) {
> + case GUEST_ACTIVITY_ACTIVE:
> + /* Always supported */
> + break;
> + case GUEST_ACTIVITY_HLT:
> + if (!nested_cpu_has_activity_state_hlt(vcpu))
> + return -EINVAL;
> + break;
> + default:
> return -EINVAL;
> + }
>
> return 0;
> }
> @@ -2710,7 +2718,7 @@ static int nested_vmx_check_guest_state(struct kvm_vcpu *vcpu,
> (vmcs12->guest_bndcfgs & MSR_IA32_BNDCFGS_RSVD)))
> return -EINVAL;
>
> - if (nested_check_guest_non_reg_state(vmcs12))
> + if (nested_check_guest_non_reg_state(vcpu, vmcs12))
> return -EINVAL;
>
> return 0;
> diff --git a/arch/x86/kvm/vmx/nested.h b/arch/x86/kvm/vmx/nested.h
> index e847ff1019a2..4a294d3ff820 100644
> --- a/arch/x86/kvm/vmx/nested.h
> +++ b/arch/x86/kvm/vmx/nested.h
> @@ -123,6 +123,11 @@ static inline bool nested_cpu_has_zero_length_injection(struct kvm_vcpu *vcpu)
> return to_vmx(vcpu)->nested.msrs.misc_low & VMX_MISC_ZERO_LEN_INS;
> }
>
> +static inline bool nested_cpu_has_activity_state_hlt(struct kvm_vcpu *vcpu)
> +{
> + return to_vmx(vcpu)->nested.msrs.misc_low & VMX_MISC_ACTIVITY_HLT;
> +}
> +
> static inline bool nested_cpu_supports_monitor_trap_flag(struct kvm_vcpu *vcpu)
> {
> return to_vmx(vcpu)->nested.msrs.procbased_ctls_high &
> --
> 2.20.1
>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] KVM: nVMX: Check that HLT activity state is supported
2019-08-13 14:35 ` Sean Christopherson
@ 2019-08-14 6:59 ` Nikita Leshenko
0 siblings, 0 replies; 3+ messages in thread
From: Nikita Leshenko @ 2019-08-14 6:59 UTC (permalink / raw)
To: Sean Christopherson; +Cc: kvm, Liran Alon, Joao Martins
> On 13 Aug 2019, at 17:35, Sean Christopherson <sean.j.christopherson@intel.com> wrote:
>
> On Tue, Aug 13, 2019 at 04:13:03PM +0300, Nikita Leshenko wrote:
>> Fail VM entry if GUEST_ACTIVITY_HLT is unsupported. According to "SDM A.6 -
>> Miscellaneous Data", VM entry should fail if the HLT activity is not marked as
>> supported on IA32_VMX_MISC MSR.
>>
>> Usermode might disable GUEST_ACTIVITY_HLT support in the vCPU with
>> vmx_restore_vmx_misc(). Before this commit VM entries would have succeeded
>> anyway.
>
> Is there a use case for disabling GUEST_ACTIVITY_HLT? Or can we simply
> disallow writes to IA32_VMX_MISC that disable GUEST_ACTIVITY_HLT?
I don't have a specific case for disabling it. Disallowing turning it off in IA32_VMX_MISC
is also possible. Because of what you said below I will submit a different patch that does
so.
Nikita
>
> To disable GUEST_ACTIVITY_HLT, userspace also has to make
> CPU_BASED_HLT_EXITING a "must be 1" control, otherwise KVM will be
> presenting a bogus model to L1.
>
> The bad model is visible to L1 if CPU_BASED_HLT_EXITING is set by L0,
> i.e. KVM is running without kvm_hlt_in_guest(), and cleared by L1. In
> that case, a HLT from L2 will be handled in L0. L0 will set the state to
> KVM_MP_STATE_HALTED and report to L1 (on a nested VM-Exit, e.g. INTR),
> that the activity state is GUEST_ACTIVITY_HLT, which from L1's perspective
> doesn't exist.
>
>> Reviewed-by: Liran Alon <liran.alon@oracle.com>
>> Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
>> Signed-off-by: Nikita Leshenko <nikita.leshchenko@oracle.com>
>> ---
>> arch/x86/kvm/vmx/nested.c | 16 ++++++++++++----
>> arch/x86/kvm/vmx/nested.h | 5 +++++
>> 2 files changed, 17 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
>> index 46af3a5e9209..3165e2f7992f 100644
>> --- a/arch/x86/kvm/vmx/nested.c
>> +++ b/arch/x86/kvm/vmx/nested.c
>> @@ -2656,11 +2656,19 @@ static int nested_vmx_check_vmcs_link_ptr(struct kvm_vcpu *vcpu,
>> /*
>> * Checks related to Guest Non-register State
>> */
>> -static int nested_check_guest_non_reg_state(struct vmcs12 *vmcs12)
>> +static int nested_check_guest_non_reg_state(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
>> {
>> - if (vmcs12->guest_activity_state != GUEST_ACTIVITY_ACTIVE &&
>> - vmcs12->guest_activity_state != GUEST_ACTIVITY_HLT)
>> + switch (vmcs12->guest_activity_state) {
>> + case GUEST_ACTIVITY_ACTIVE:
>> + /* Always supported */
>> + break;
>> + case GUEST_ACTIVITY_HLT:
>> + if (!nested_cpu_has_activity_state_hlt(vcpu))
>> + return -EINVAL;
>> + break;
>> + default:
>> return -EINVAL;
>> + }
>>
>> return 0;
>> }
>> @@ -2710,7 +2718,7 @@ static int nested_vmx_check_guest_state(struct kvm_vcpu *vcpu,
>> (vmcs12->guest_bndcfgs & MSR_IA32_BNDCFGS_RSVD)))
>> return -EINVAL;
>>
>> - if (nested_check_guest_non_reg_state(vmcs12))
>> + if (nested_check_guest_non_reg_state(vcpu, vmcs12))
>> return -EINVAL;
>>
>> return 0;
>> diff --git a/arch/x86/kvm/vmx/nested.h b/arch/x86/kvm/vmx/nested.h
>> index e847ff1019a2..4a294d3ff820 100644
>> --- a/arch/x86/kvm/vmx/nested.h
>> +++ b/arch/x86/kvm/vmx/nested.h
>> @@ -123,6 +123,11 @@ static inline bool nested_cpu_has_zero_length_injection(struct kvm_vcpu *vcpu)
>> return to_vmx(vcpu)->nested.msrs.misc_low & VMX_MISC_ZERO_LEN_INS;
>> }
>>
>> +static inline bool nested_cpu_has_activity_state_hlt(struct kvm_vcpu *vcpu)
>> +{
>> + return to_vmx(vcpu)->nested.msrs.misc_low & VMX_MISC_ACTIVITY_HLT;
>> +}
>> +
>> static inline bool nested_cpu_supports_monitor_trap_flag(struct kvm_vcpu *vcpu)
>> {
>> return to_vmx(vcpu)->nested.msrs.procbased_ctls_high &
>> --
>> 2.20.1
>>
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2019-08-14 7:00 UTC | newest]
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2019-08-13 13:13 [PATCH] KVM: nVMX: Check that HLT activity state is supported Nikita Leshenko
2019-08-13 14:35 ` Sean Christopherson
2019-08-14 6:59 ` Nikita Leshenko
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