Re: [PATCH v2 25/43] KVM: VMX: Save/restore IRQs (instead of CLI/STI) during PI pre/post block

[Maxim Levitsky]

On Fri, 2021-10-08 at 19:12 -0700, Sean Christopherson wrote:
> Save/restore IRQs when disabling IRQs in posted interrupt pre/post block
> in preparation for moving the code into vcpu_put/load(), and thus may be
> called with IRQs already disabled.
> 
> No functional changed intended.
> 
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> ---
>  arch/x86/kvm/vmx/posted_intr.c | 13 +++++++------
>  1 file changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c
> index 239e0e72a0dd..414ea6972b5c 100644
> --- a/arch/x86/kvm/vmx/posted_intr.c
> +++ b/arch/x86/kvm/vmx/posted_intr.c
> @@ -140,6 +140,7 @@ int pi_pre_block(struct kvm_vcpu *vcpu)
>  {
>  	struct pi_desc old, new;
>  	struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
> +	unsigned long flags;
>  
>  	if (!kvm_arch_has_assigned_device(vcpu->kvm) ||
>  	    !irq_remapping_cap(IRQ_POSTING_CAP) ||
> @@ -147,8 +148,7 @@ int pi_pre_block(struct kvm_vcpu *vcpu)
>  	    vmx_interrupt_blocked(vcpu))
>  		return 0;
>  
> -	WARN_ON(irqs_disabled());
> -	local_irq_disable();
> +	local_irq_save(flags);
>  
>  	vcpu->pre_pcpu = vcpu->cpu;
>  	spin_lock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->cpu));
> @@ -171,19 +171,20 @@ int pi_pre_block(struct kvm_vcpu *vcpu)
>  	if (pi_test_on(pi_desc))
>  		__pi_post_block(vcpu);
>  
> -	local_irq_enable();
> +	local_irq_restore(flags);
>  	return (vcpu->pre_pcpu == -1);
>  }
>  
>  void pi_post_block(struct kvm_vcpu *vcpu)
>  {
> +	unsigned long flags;
> +
>  	if (vcpu->pre_pcpu == -1)
>  		return;
>  
> -	WARN_ON(irqs_disabled());
> -	local_irq_disable();
> +	local_irq_save(flags);
>  	__pi_post_block(vcpu);
> -	local_irq_enable();
> +	local_irq_restore(flags);
>  }
>  
>  /*
Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>

Best regards,
	Maxim Levitsky