linux-kernel - Re: [PATCH] x86/irq: use lapic_vector_set_in_irr to check for pending vectors in fixup

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Date: Mon, 6 May 2024 10:38:41 -0700
From: Jacob Pan <jacob.jun.pan@...ux.intel.com>
To: Imran Khan <imran.f.khan@...cle.com>
Cc: tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
 dave.hansen@...ux.intel.com, hpa@...or.com, x86@...nel.org,
 linux-kernel@...r.kernel.org, jacob.jun.pan@...ux.intel.com
Subject: Re: [PATCH] x86/irq: use lapic_vector_set_in_irr to check for
 pending vectors in fixup_irqs.

Hi Imran,

On Mon,  6 May 2024 21:16:34 +1000, Imran Khan <imran.f.khan@...cle.com>
wrote:

> No functional change, just using readily available helper which
> uses the same logic, that has been used here.
> 
> Signed-off-by: Imran Khan <imran.f.khan@...cle.com>
> ---
>  arch/x86/kernel/irq.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
> index 35fde0107901d..71432e42275c4 100644
> --- a/arch/x86/kernel/irq.c
> +++ b/arch/x86/kernel/irq.c
> @@ -339,7 +339,7 @@
> DEFINE_IDTENTRY_SYSVEC_SIMPLE(sysvec_kvm_posted_intr_nested_ipi) /* A cpu
> has been removed from cpu_online_mask.  Reset irq affinities. */ void
> fixup_irqs(void) {
> -	unsigned int irr, vector;
> +	unsigned int vector;
>  	struct irq_desc *desc;
>  	struct irq_data *data;
>  	struct irq_chip *chip;
> @@ -366,8 +366,7 @@ void fixup_irqs(void)
>  		if (IS_ERR_OR_NULL(__this_cpu_read(vector_irq[vector])))
>  			continue;
>  
> -		irr = apic_read(APIC_IRR + (vector / 32 * 0x10));
> -		if (irr  & (1 << (vector % 32))) {
> +		if (lapic_vector_set_in_irr(vector)) {
>  			desc = __this_cpu_read(vector_irq[vector]);
>  
>  			raw_spin_lock(&desc->lock);
I have a similar refactoring as part of the posted MSI series, but I
totally missed the existing helper lapic_vector_set_in_irr().

https://lore.kernel.org/lkml/171448372145.10875.6906928487300074547.tip-bot2@tip-bot2/

Let me send out a fix patch against tip tree.

--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -505,13 +505,7 @@ static inline bool lapic_vector_set_in_irr(unsigned int vector)

 static inline bool is_vector_pending(unsigned int vector)
 {
-       unsigned int irr;
-
-       irr = apic_read(APIC_IRR + (vector / 32 * 0x10));
-       if (irr  & (1 << (vector % 32)))
-               return true;
-
-       return pi_pending_this_cpu(vector);
+       return lapic_vector_set_in_irr(vector) || pi_pending_this_cpu(vector);
 }

Thanks,

Jacob