linux-kernel - Re: [RESEND PATCH 5/6] KVM: x86/VMX: add kvm_vmx_reinject_nmi

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Date:   Thu, 24 Nov 2022 10:46:02 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     "Li, Xin3" <xin3.li@...el.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "bp@...en8.de" <bp@...en8.de>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "hpa@...or.com" <hpa@...or.com>,
        "Tian, Kevin" <kevin.tian@...el.com>
Subject: Re: [RESEND PATCH 5/6] KVM: x86/VMX: add kvm_vmx_reinject_nmi_irq()
 for NMI/IRQ reinjection

On Wed, Nov 23, 2022 at 08:42:51PM +0000, Sean Christopherson wrote:
>  arch/x86/kvm/kvm_cache_regs.h | 16 +++++------
>  arch/x86/kvm/vmx/vmenter.S    |  4 +--
>  arch/x86/kvm/vmx/vmx.c        | 51 ++++++++++++++++++-----------------
>  arch/x86/kvm/vmx/vmx.h        |  2 +-
>  arch/x86/kvm/x86.h            |  6 ++---
>  5 files changed, 41 insertions(+), 38 deletions(-)
> 
> diff --git a/arch/x86/kvm/kvm_cache_regs.h b/arch/x86/kvm/kvm_cache_regs.h
> index c09174f73a34..af9bd0374915 100644
> --- a/arch/x86/kvm/kvm_cache_regs.h
> +++ b/arch/x86/kvm/kvm_cache_regs.h
> @@ -50,26 +50,26 @@ BUILD_KVM_GPR_ACCESSORS(r15, R15)
>   * 1	  0	  register in vcpu->arch
>   * 1	  1	  register in vcpu->arch, needs to be stored back
>   */
> -static inline bool kvm_register_is_available(struct kvm_vcpu *vcpu,
> -					     enum kvm_reg reg)
> +static __always_inline bool kvm_register_is_available(struct kvm_vcpu *vcpu,
> +						      enum kvm_reg reg)
>  {
>  	return test_bit(reg, (unsigned long *)&vcpu->arch.regs_avail);
>  }
>  
> -static inline bool kvm_register_is_dirty(struct kvm_vcpu *vcpu,
> -					 enum kvm_reg reg)
> +static __always_inline bool kvm_register_is_dirty(struct kvm_vcpu *vcpu,
> +						  enum kvm_reg reg)
>  {
>  	return test_bit(reg, (unsigned long *)&vcpu->arch.regs_dirty);
>  }
>  
> -static inline void kvm_register_mark_available(struct kvm_vcpu *vcpu,
> -					       enum kvm_reg reg)
> +static __always_inline void kvm_register_mark_available(struct kvm_vcpu *vcpu,
> +							enum kvm_reg reg)
>  {
>  	__set_bit(reg, (unsigned long *)&vcpu->arch.regs_avail);
>  }
>  
> -static inline void kvm_register_mark_dirty(struct kvm_vcpu *vcpu,
> -					   enum kvm_reg reg)
> +static __always_inline void kvm_register_mark_dirty(struct kvm_vcpu *vcpu,
> +						    enum kvm_reg reg)
>  {
>  	__set_bit(reg, (unsigned long *)&vcpu->arch.regs_avail);
>  	__set_bit(reg, (unsigned long *)&vcpu->arch.regs_dirty);

You'll have to consider include/asm-generic/bitops/instrumented-non-atomic.h
and friend, and the above should probably switch to using:

  arch_test_bit(), arch___set_bit() resp.

to avoid the explicit instrumentation.