The function svm_refresh_apicv_exec_ctrl() always returning prematurely
as kvm_vcpu_apicv_active() always return false when calling from
the function arch/x86/kvm/x86.c:kvm_vcpu_deactivate_apicv().
This is because the apicv_active is set to false just before calling
refresh_apicv_exec_ctrl().
Also, we need to mark VMCB_AVIC bit as dirty instead of VMCB_INTR.
So, fix svm_refresh_apicv_exec_ctrl() to properly deactivate AVIC.
Fixes: 67034bb9dd5e ('KVM: SVM: Add irqchip_split() checks before enabling AVIC')
Cc: Radim Krčmář <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Signed-off-by: Suravee Suthikulpanit <[email protected]>
---
arch/x86/kvm/svm.c | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index d35c9002f282..59b1f68060c7 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -390,6 +390,8 @@ static int nested_svm_vmexit(struct vcpu_svm *svm);
static int nested_svm_check_exception(struct vcpu_svm *svm, unsigned nr,
bool has_error_code, u32 error_code);
+static bool svm_get_enable_apicv(struct kvm_vcpu *vcpu);
+
enum {
VMCB_INTERCEPTS, /* Intercept vectors, TSC offset,
pause filter count */
@@ -478,6 +480,12 @@ static inline struct vcpu_svm *to_svm(struct kvm_vcpu *vcpu)
return container_of(vcpu, struct vcpu_svm, vcpu);
}
+static bool is_avic_active(struct vcpu_svm *svm)
+{
+ return (svm_get_enable_apicv(&svm->vcpu) &&
+ svm->vmcb->control.int_ctl & AVIC_ENABLE_MASK);
+}
+
static inline void avic_update_vapic_bar(struct vcpu_svm *svm, u64 data)
{
svm->vmcb->control.avic_vapic_bar = data & VMCB_AVIC_APIC_BAR_MASK;
@@ -5108,17 +5116,23 @@ static void svm_hwapic_isr_update(struct kvm_vcpu *vcpu, int max_isr)
{
}
-/* Note: Currently only used by Hyper-V. */
-static void svm_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu)
+static void svm_deactivate_avic(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm = to_svm(vcpu);
struct vmcb *vmcb = svm->vmcb;
- if (!kvm_vcpu_apicv_active(&svm->vcpu))
+ if (!lapic_in_kernel(vcpu) || !is_avic_active(svm))
return;
vmcb->control.int_ctl &= ~AVIC_ENABLE_MASK;
- mark_dirty(vmcb, VMCB_INTR);
+ mark_dirty(vmcb, VMCB_AVIC);
+}
+
+/* Note: Currently only used by Hyper-V. */
+static void svm_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu)
+{
+ if (!kvm_vcpu_apicv_active(vcpu))
+ svm_deactivate_avic(vcpu);
}
static void svm_load_eoi_exitmap(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap)
--
2.17.1
On 29/01/19 09:09, Suthikulpanit, Suravee wrote:
> The function svm_refresh_apicv_exec_ctrl() always returning prematurely
> as kvm_vcpu_apicv_active() always return false when calling from
> the function arch/x86/kvm/x86.c:kvm_vcpu_deactivate_apicv().
> This is because the apicv_active is set to false just before calling
> refresh_apicv_exec_ctrl().
>
> Also, we need to mark VMCB_AVIC bit as dirty instead of VMCB_INTR.
>
> So, fix svm_refresh_apicv_exec_ctrl() to properly deactivate AVIC.
>
> Fixes: 67034bb9dd5e ('KVM: SVM: Add irqchip_split() checks before enabling AVIC')
Having the lapic_in_kernel check in your code is a bit ugly - the caller
should check it. And actually, even though it doesn't check it right
now, svm_refresh_apicv_exec_ctrl is only reachable if lapic_in_kernel
returns true; see the KVM_CAP_HYPERV_SYNIC case of
kvm_vcpu_ioctl_enable_cap.
What about this simpler patch:
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 01b66bbcdd7a..74ceda470eae 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -5122,11 +5122,11 @@ static void svm_refresh_apicv_exec_ctrl(
struct vcpu_svm *svm = to_svm(vcpu);
struct vmcb *vmcb = svm->vmcb;
- if (!kvm_vcpu_apicv_active(&svm->vcpu))
- return;
-
- vmcb->control.int_ctl &= ~AVIC_ENABLE_MASK;
- mark_dirty(vmcb, VMCB_INTR);
+ if (kvm_vcpu_apicv_active(vcpu))
+ vmcb->control.int_ctl |= AVIC_ENABLE_MASK;
+ else
+ vmcb->control.int_ctl &= ~AVIC_ENABLE_MASK;
+ mark_dirty(vmcb, VMCB_AVIC);
}
static void svm_load_eoi_exitmap(struct kvm_vcpu *vcpu, u64
*eoi_exit_bitmap)
?
Thanks,
Paolo
Paolo,
On 1/30/19 11:22 PM, Paolo Bonzini wrote:
> On 29/01/19 09:09, Suthikulpanit, Suravee wrote:
>> The function svm_refresh_apicv_exec_ctrl() always returning prematurely
>> as kvm_vcpu_apicv_active() always return false when calling from
>> the function arch/x86/kvm/x86.c:kvm_vcpu_deactivate_apicv().
>> This is because the apicv_active is set to false just before calling
>> refresh_apicv_exec_ctrl().
>>
>> Also, we need to mark VMCB_AVIC bit as dirty instead of VMCB_INTR.
>>
>> So, fix svm_refresh_apicv_exec_ctrl() to properly deactivate AVIC.
>>
>> Fixes: 67034bb9dd5e ('KVM: SVM: Add irqchip_split() checks before enabling AVIC')
>
> Having the lapic_in_kernel check in your code is a bit ugly - the caller
> should check it. And actually, even though it doesn't check it right
> now, svm_refresh_apicv_exec_ctrl is only reachable if lapic_in_kernel
> returns true; see the KVM_CAP_HYPERV_SYNIC case of
> kvm_vcpu_ioctl_enable_cap.
>
> What about this simpler patch:
>
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 01b66bbcdd7a..74ceda470eae 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -5122,11 +5122,11 @@ static void svm_refresh_apicv_exec_ctrl(
> struct vcpu_svm *svm = to_svm(vcpu);
> struct vmcb *vmcb = svm->vmcb;
>
> - if (!kvm_vcpu_apicv_active(&svm->vcpu))
> - return;
> -
> - vmcb->control.int_ctl &= ~AVIC_ENABLE_MASK;
> - mark_dirty(vmcb, VMCB_INTR);
> + if (kvm_vcpu_apicv_active(vcpu))
> + vmcb->control.int_ctl |= AVIC_ENABLE_MASK;
> + else
> + vmcb->control.int_ctl &= ~AVIC_ENABLE_MASK;
> + mark_dirty(vmcb, VMCB_AVIC);
> }
>
> static void svm_load_eoi_exitmap(struct kvm_vcpu *vcpu, u64
> *eoi_exit_bitmap)
>
> ?
>
> Thanks,
>
> Paolo
>
Yes, this would work.
This patch is actually a precursor of a patch series that I am working on
to allow AVIC enabling/disabling during run-time. I will send out a series
for RFC soon.
Thanks,
Suravee
Paolo,
On 2/1/19 6:01 PM, Suravee Suthikulpanit wrote:
> Paolo,
>
> On 1/30/19 11:22 PM, Paolo Bonzini wrote:
>> On 29/01/19 09:09, Suthikulpanit, Suravee wrote:
>>> The function svm_refresh_apicv_exec_ctrl() always returning prematurely
>>> as kvm_vcpu_apicv_active() always return false when calling from
>>> the function arch/x86/kvm/x86.c:kvm_vcpu_deactivate_apicv().
>>> This is because the apicv_active is set to false just before calling
>>> refresh_apicv_exec_ctrl().
>>>
>>> Also, we need to mark VMCB_AVIC bit as dirty instead of VMCB_INTR.
>>>
>>> So, fix svm_refresh_apicv_exec_ctrl() to properly deactivate AVIC.
>>>
>>> Fixes: 67034bb9dd5e ('KVM: SVM: Add irqchip_split() checks before enabling AVIC')
>>
>> Having the lapic_in_kernel check in your code is a bit ugly - the caller
>> should check it. And actually, even though it doesn't check it right
>> now, svm_refresh_apicv_exec_ctrl is only reachable if lapic_in_kernel
>> returns true; see the KVM_CAP_HYPERV_SYNIC case of
>> kvm_vcpu_ioctl_enable_cap.
>>
>> What about this simpler patch:
>>
>> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
>> index 01b66bbcdd7a..74ceda470eae 100644
>> --- a/arch/x86/kvm/svm.c
>> +++ b/arch/x86/kvm/svm.c
>> @@ -5122,11 +5122,11 @@ static void svm_refresh_apicv_exec_ctrl(
>> struct vcpu_svm *svm = to_svm(vcpu);
>> struct vmcb *vmcb = svm->vmcb;
>>
>> - if (!kvm_vcpu_apicv_active(&svm->vcpu))
>> - return;
>> -
>> - vmcb->control.int_ctl &= ~AVIC_ENABLE_MASK;
>> - mark_dirty(vmcb, VMCB_INTR);
>> + if (kvm_vcpu_apicv_active(vcpu))
>> + vmcb->control.int_ctl |= AVIC_ENABLE_MASK;
>> + else
>> + vmcb->control.int_ctl &= ~AVIC_ENABLE_MASK;
>> + mark_dirty(vmcb, VMCB_AVIC);
>> }
>>
>> static void svm_load_eoi_exitmap(struct kvm_vcpu *vcpu, u64
>> *eoi_exit_bitmap)
>>
>> ?
>>
>> Thanks,
>>
>> Paolo
>>
>
> Yes, this would work.
>
> This patch is actually a precursor of a patch series that I am working on
> to allow AVIC enabling/disabling during run-time. I will send out a series
> for RFC soon.
>
> Thanks,
> Suravee
Not sure if you have already applied this change. Anyhow, I just want to let
you know that I have included the change you suggested as patch 1/8 of
the RFC series
"KVM: x86: svm: Enabling AVIC with in kernel irqchip"
Thanks,
Suravee