Re: [PATCH] x86/irq: use NR_ISAIRQS instead of open-coded value

[Denis Mukhin <dmkhn@xxxxxxxxx>]

On Friday, March 14th, 2025 at 1:51 AM, Jan Beulich <jbeulich@xxxxxxxx> wrote:

> 
> 
> On 14.03.2025 02:20, dmkhn@xxxxxxxxx wrote:
> 
> > Replace the open-coded value 16 with the NR_ISAIRQS symbol to enhance
> > readability.
> > 
> > No functional changes.
> > 
> > Signed-off-by: Denis Mukhin dmukhin@xxxxxxxx
> > ---
> > xen/arch/x86/hvm/dm.c | 2 +-
> > xen/arch/x86/hvm/irq.c | 17 +++++++++--------
> > xen/arch/x86/hvm/vlapic.c | 10 +++++-----
> > xen/arch/x86/hvm/vpic.c | 4 ++--
> > xen/arch/x86/include/asm/irq.h | 2 +-
> > xen/arch/x86/io_apic.c | 12 ++++++------
> > xen/arch/x86/irq.c | 6 +++---
> > 7 files changed, 27 insertions(+), 26 deletions(-)
> > 
> > diff --git a/xen/arch/x86/hvm/dm.c b/xen/arch/x86/hvm/dm.c
> > index a1f7a4d30a..36d47664e9 100644
> > --- a/xen/arch/x86/hvm/dm.c
> > +++ b/xen/arch/x86/hvm/dm.c
> > @@ -90,7 +90,7 @@ static int set_pci_intx_level(struct domain *d, uint16_t 
> > domain,
> > static int set_isa_irq_level(struct domain *d, uint8_t isa_irq,
> > uint8_t level)
> > {
> > - if ( isa_irq > 15 )
> > + if ( isa_irq >= NR_ISAIRQS )
> > return -EINVAL;
> > 
> > switch ( level )
> > diff --git a/xen/arch/x86/hvm/irq.c b/xen/arch/x86/hvm/irq.c
> > index 1eab44defc..1f7d8ca43e 100644
> > --- a/xen/arch/x86/hvm/irq.c
> > +++ b/xen/arch/x86/hvm/irq.c
> > @@ -209,7 +209,7 @@ int hvm_isa_irq_assert(struct domain *d, unsigned int 
> > isa_irq,
> > unsigned int gsi = hvm_isa_irq_to_gsi(isa_irq);
> > int vector = -1;
> > 
> > - ASSERT(isa_irq <= 15);
> > + ASSERT(isa_irq < NR_ISAIRQS);
> > 
> > spin_lock(&d->arch.hvm.irq_lock);
> > 
> > @@ -231,7 +231,7 @@ void hvm_isa_irq_deassert(
> > struct hvm_irq *hvm_irq = hvm_domain_irq(d);
> > unsigned int gsi = hvm_isa_irq_to_gsi(isa_irq);
> > 
> > - ASSERT(isa_irq <= 15);
> > + ASSERT(isa_irq < NR_ISAIRQS);
> > 
> > spin_lock(&d->arch.hvm.irq_lock);
> > 
> > @@ -266,12 +266,12 @@ static void hvm_set_callback_irq_level(struct vcpu *v)
> > if ( asserted && (hvm_irq->gsi_assert_count[gsi]++ == 0) )
> > {
> > vioapic_irq_positive_edge(d, gsi);
> > - if ( gsi <= 15 )
> > + if ( gsi < NR_ISAIRQS )
> > vpic_irq_positive_edge(d, gsi);
> > }
> > else if ( !asserted && (--hvm_irq->gsi_assert_count[gsi] == 0) )
> > {
> > - if ( gsi <= 15 )
> > + if ( gsi < NR_ISAIRQS )
> > vpic_irq_negative_edge(d, gsi);
> > }
> > break;
> > @@ -328,7 +328,7 @@ int hvm_set_pci_link_route(struct domain *d, u8 link, 
> > u8 isa_irq)
> > u8 old_isa_irq;
> > int i;
> > 
> > - if ( (link > 3) || (isa_irq > 15) )
> > + if ( (link > 3) || (isa_irq >= NR_ISAIRQS) )
> > return -EINVAL;
> > 
> > spin_lock(&d->arch.hvm.irq_lock);
> > @@ -440,7 +440,8 @@ void hvm_set_callback_via(struct domain *d, uint64_t 
> > via)
> > {
> > case HVMIRQ_callback_gsi:
> > gsi = hvm_irq->callback_via.gsi;
> > - if ( (--hvm_irq->gsi_assert_count[gsi] == 0) && (gsi <= 15) )
> > + if ( (--hvm_irq->gsi_assert_count[gsi] == 0) &&
> > + (gsi < NR_ISAIRQS) )
> > vpic_irq_negative_edge(d, gsi);
> > break;
> > case HVMIRQ_callback_pci_intx:
> > @@ -464,7 +465,7 @@ void hvm_set_callback_via(struct domain *d, uint64_t 
> > via)
> > (hvm_irq->gsi_assert_count[gsi]++ == 0) )
> > {
> > vioapic_irq_positive_edge(d, gsi);
> > - if ( gsi <= 15 )
> > + if ( gsi < NR_ISAIRQS )
> > vpic_irq_positive_edge(d, gsi);
> > }
> > break;
> > @@ -764,7 +765,7 @@ static int cf_check irq_check_link(const struct domain 
> > *d,
> > return -EINVAL;
> > 
> > for ( link = 0; link < ARRAY_SIZE(pci_link->route); link++ )
> > - if ( pci_link->route[link] > 15 )
> > + if ( pci_link->route[link] >= NR_ISAIRQS )
> > {
> > printk(XENLOG_G_ERR
> > "HVM restore: PCI-ISA link %u out of range (%u)\n",
> 
> 
> Up to here I agree with the adjustments made, but ...
> 
> > --- a/xen/arch/x86/hvm/vlapic.c
> > +++ b/xen/arch/x86/hvm/vlapic.c
> > @@ -123,7 +123,7 @@ static void vlapic_error(struct vlapic *vlapic, 
> > unsigned int err_bit)
> > * will end up back here. Break the cycle by only injecting LVTERR
> > * if it will succeed, and folding in RECVILL otherwise.
> > */
> > - if ( (lvterr & APIC_VECTOR_MASK) >= 16 )
> > + if ( (lvterr & APIC_VECTOR_MASK) >= NR_ISAIRQS )
> > inj = true;
> > else
> > set_bit(ilog2(APIC_ESR_RECVILL), &vlapic->hw.pending_esr);
> > @@ -136,7 +136,7 @@ static void vlapic_error(struct vlapic *vlapic, 
> > unsigned int err_bit)
> > 
> > bool vlapic_test_irq(const struct vlapic *vlapic, uint8_t vec)
> > {
> > - if ( unlikely(vec < 16) )
> > + if ( unlikely(vec < NR_ISAIRQS) )
> > return false;
> > 
> > if ( hvm_funcs.test_pir &&
> > @@ -150,7 +150,7 @@ void vlapic_set_irq(struct vlapic *vlapic, uint8_t vec, 
> > uint8_t trig)
> > {
> > struct vcpu *target = vlapic_vcpu(vlapic);
> > 
> > - if ( unlikely(vec < 16) )
> > + if ( unlikely(vec < NR_ISAIRQS) )
> > {
> > vlapic_error(vlapic, ilog2(APIC_ESR_RECVILL));
> > return;
> > @@ -523,7 +523,7 @@ void vlapic_ipi(
> > struct vlapic *target = vlapic_lowest_prio(
> > vlapic_domain(vlapic), vlapic, short_hand, dest, dest_mode);
> > 
> > - if ( unlikely((icr_low & APIC_VECTOR_MASK) < 16) )
> > + if ( unlikely((icr_low & APIC_VECTOR_MASK) < NR_ISAIRQS) )
> > vlapic_error(vlapic, ilog2(APIC_ESR_SENDILL));
> > else if ( target )
> > vlapic_accept_irq(vlapic_vcpu(target), icr_low);
> > @@ -531,7 +531,7 @@ void vlapic_ipi(
> > }
> > 
> > case APIC_DM_FIXED:
> > - if ( unlikely((icr_low & APIC_VECTOR_MASK) < 16) )
> > + if ( unlikely((icr_low & APIC_VECTOR_MASK) < NR_ISAIRQS) )
> > {
> > vlapic_error(vlapic, ilog2(APIC_ESR_SENDILL));
> > break;
> 
> 
> ... the 16 here has a different origin (in the local APIC spec). Changes
> further down look okay again.

Sorry for that, I did not verify with the spec.

Thanks!

> 
> Jan