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Trivial cleanups for the posted MSI interrupt handling

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Merge tag 'x86-irq-2026-02-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 irq updates from Thomas Gleixner:
 "Trivial cleanups for the posted MSI interrupt handling"

* tag 'x86-irq-2026-02-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/irq_remapping: Sanitize posted_msi_supported()
  x86/irq: Cleanup posted MSI code
This commit is contained in:
Linus Torvalds 2026-02-10 17:39:08 -08:00
commit 2619c62b7e
3 changed files with 18 additions and 22 deletions
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5
arch/x86/include/asm/irq_remapping.h
View file

@ -67,9 +67,10 @@ static inline struct irq_domain *arch_get_ir_parent_domain(void)
extern bool enable_posted_msi;
static inline bool posted_msi_supported(void)
static inline bool posted_msi_enabled(void)
{
return enable_posted_msi && irq_remapping_cap(IRQ_POSTING_CAP);
return IS_ENABLED(CONFIG_X86_POSTED_MSI) &&
enable_posted_msi && irq_remapping_cap(IRQ_POSTING_CAP);
}
#else /* CONFIG_IRQ_REMAP */

31
arch/x86/kernel/irq.c
View file

@ -420,11 +420,9 @@ static DEFINE_PER_CPU_CACHE_HOT(bool, posted_msi_handler_active);
void intel_posted_msi_init(void)
{
u32 destination;
u32 apic_id;
u32 destination, apic_id;
this_cpu_write(posted_msi_pi_desc.nv, POSTED_MSI_NOTIFICATION_VECTOR);
/*
* APIC destination ID is stored in bit 8:15 while in XAPIC mode.
* VT-d spec. CH 9.11
@ -468,8 +466,8 @@ static __always_inline bool handle_pending_pir(unsigned long *pir, struct pt_reg
}
/*
* Performance data shows that 3 is good enough to harvest 90+% of the benefit
* on high IRQ rate workload.
* Performance data shows that 3 is good enough to harvest 90+% of the
* benefit on high interrupt rate workloads.
*/
#define MAX_POSTED_MSI_COALESCING_LOOP 3
@ -479,11 +477,8 @@ static __always_inline bool handle_pending_pir(unsigned long *pir, struct pt_reg
*/
DEFINE_IDTENTRY_SYSVEC(sysvec_posted_msi_notification)
{
struct pi_desc *pid = this_cpu_ptr(&posted_msi_pi_desc);
struct pt_regs *old_regs = set_irq_regs(regs);
struct pi_desc *pid;
int i = 0;
pid = this_cpu_ptr(&posted_msi_pi_desc);
/* Mark the handler active for intel_ack_posted_msi_irq() */
__this_cpu_write(posted_msi_handler_active, true);
@ -491,25 +486,25 @@ DEFINE_IDTENTRY_SYSVEC(sysvec_posted_msi_notification)
irq_enter();
/*
* Max coalescing count includes the extra round of handle_pending_pir
* after clearing the outstanding notification bit. Hence, at most
* MAX_POSTED_MSI_COALESCING_LOOP - 1 loops are executed here.
* Loop only MAX_POSTED_MSI_COALESCING_LOOP - 1 times here to take
* the final handle_pending_pir() invocation after clearing the
* outstanding notification bit into account.
*/
while (++i < MAX_POSTED_MSI_COALESCING_LOOP) {
for (int i = 1; i < MAX_POSTED_MSI_COALESCING_LOOP; i++) {
if (!handle_pending_pir(pid->pir, regs))
break;
}
/*
* Clear outstanding notification bit to allow new IRQ notifications,
* do this last to maximize the window of interrupt coalescing.
* Clear the outstanding notification bit to rearm the notification
* mechanism.
*/
pi_clear_on(pid);
/*
* There could be a race of PI notification and the clearing of ON bit,
* process PIR bits one last time such that handling the new interrupts
* are not delayed until the next IRQ.
* Clearing the ON bit can race with a notification. Process the
* PIR bits one last time so that handling the new interrupts is
* not delayed until the next notification happens.
*/
handle_pending_pir(pid->pir, regs);

4
drivers/iommu/intel/irq_remapping.c
View file

@ -1368,7 +1368,7 @@ static void intel_irq_remapping_prepare_irte(struct intel_ir_data *data,
break;
case X86_IRQ_ALLOC_TYPE_PCI_MSI:
case X86_IRQ_ALLOC_TYPE_PCI_MSIX:
if (posted_msi_supported()) {
if (posted_msi_enabled()) {
prepare_irte_posted(irte);
data->irq_2_iommu.posted_msi = 1;
}
@ -1460,7 +1460,7 @@ static int intel_irq_remapping_alloc(struct irq_domain *domain,
irq_data->hwirq = (index << 16) + i;
irq_data->chip_data = ird;
if (posted_msi_supported() &&
if (posted_msi_enabled() &&
((info->type == X86_IRQ_ALLOC_TYPE_PCI_MSI) ||
(info->type == X86_IRQ_ALLOC_TYPE_PCI_MSIX)))
irq_data->chip = &intel_ir_chip_post_msi;