KVM: x86/pmu: Introduce passthrough vPM

[RFC PATCH 08/41] KVM: x86/pmu: Add get virtual LVTPC_MASK bit function

Posted by Xiong Zhang 2 years ago

From: Xiong Zhang <xiong.y.zhang@intel.com>

On PMU passthrough mode, guest virtual LVTPC_MASK bit must be reflected
onto HW, especially when guest clear it, the HW bit should be cleared also.
Otherwise processor can't generate PMI until the HW mask bit is cleared.

This commit add a function to get virtual LVTPC_MASK bit, so that
it can be set onto HW later.

Signed-off-by: Xiong Zhang <xiong.y.zhang@intel.com>
---
 arch/x86/kvm/lapic.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index e30641d5ac90..dafae44325d1 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -277,4 +277,10 @@ static inline u8 kvm_xapic_id(struct kvm_lapic *apic)
 {
 	return kvm_lapic_get_reg(apic, APIC_ID) >> 24;
 }
+
+static inline bool kvm_lapic_get_lvtpc_mask(struct kvm_vcpu *vcpu)
+{
+	return lapic_in_kernel(vcpu) &&
+	       (kvm_lapic_get_reg(vcpu->arch.apic, APIC_LVTPC) & APIC_LVT_MASKED);
+}
 #endif
-- 
2.34.1

Re: [RFC PATCH 08/41] KVM: x86/pmu: Add get virtual LVTPC_MASK bit function

Posted by Sean Christopherson 1 year, 10 months ago

On Fri, Jan 26, 2024, Xiong Zhang wrote:
> From: Xiong Zhang <xiong.y.zhang@intel.com>
> 
> On PMU passthrough mode, guest virtual LVTPC_MASK bit must be reflected
> onto HW, especially when guest clear it, the HW bit should be cleared also.
> Otherwise processor can't generate PMI until the HW mask bit is cleared.
> 
> This commit add a function to get virtual LVTPC_MASK bit, so that

No "This commit", "This patch", or any other variation.  Please read through:

  Documentation/process/maintainer-tip.rst 
  Documentation/process/maintainer-kvm-x86.rst

> it can be set onto HW later.
> 
> Signed-off-by: Xiong Zhang <xiong.y.zhang@intel.com>
> ---
>  arch/x86/kvm/lapic.h | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
> index e30641d5ac90..dafae44325d1 100644
> --- a/arch/x86/kvm/lapic.h
> +++ b/arch/x86/kvm/lapic.h
> @@ -277,4 +277,10 @@ static inline u8 kvm_xapic_id(struct kvm_lapic *apic)
>  {
>  	return kvm_lapic_get_reg(apic, APIC_ID) >> 24;
>  }
> +
> +static inline bool kvm_lapic_get_lvtpc_mask(struct kvm_vcpu *vcpu)
> +{
> +	return lapic_in_kernel(vcpu) &&
> +	       (kvm_lapic_get_reg(vcpu->arch.apic, APIC_LVTPC) & APIC_LVT_MASKED);
> +}

As suggested in the previous patch, I'm pretty sure we can safely omit this
helper.

>  #endif
> -- 
> 2.34.1
>