[tip: x86/irq] x86/irq_remapping: Sanitize posted_msi_supported()

["tip-bot2 for Thomas Gleixner" <tip-bot2@linutronix.de>]

The following commit has been merged into the x86/irq branch of tip:

Commit-ID:     64d4c88270cf90089434e3db67ed443fd982a9a2
Gitweb:        https://git.kernel.org/tip/64d4c88270cf90089434e3db67ed443fd982a9a2
Author:        Thomas Gleixner <tglx@linutronix.de>
AuthorDate:    Tue, 25 Nov 2025 22:50:49 +01:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Wed, 17 Dec 2025 18:44:17 +01:00

x86/irq_remapping: Sanitize posted_msi_supported()

posted_msi_supported() is a misnomer as it actually checks whether it is
enabled or not. Aside of that this does not take CONFIG_X86_POSTED_MSI into
account which is required to actually use it.

Rename it to posted_msi_enabled() and make the return value depend on
CONFIG_X86_POSTED_MSI, which allows the compiler to eliminate the related
dead code and data if disabled:

  text	   data	    bss	    dec	    hex	filename
  10046	    701	   3296	  14043	   36db	drivers/iommu/intel/irq_remapping.o
   9904	    413	   3296	  13613	   352d	drivers/iommu/intel/irq_remapping.o

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://patch.msgid.link/20251125214631.170499997@linutronix.de
---
 arch/x86/include/asm/irq_remapping.h | 5 +++--
 drivers/iommu/intel/irq_remapping.c  | 4 ++--
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/irq_remapping.h b/arch/x86/include/asm/irq_remapping.h
index 4e55d17..37b94f4 100644
--- a/arch/x86/include/asm/irq_remapping.h
+++ b/arch/x86/include/asm/irq_remapping.h
@@ -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 */
diff --git a/drivers/iommu/intel/irq_remapping.c b/drivers/iommu/intel/irq_remapping.c
index 8bcbfe3..ecb591e 100644
--- a/drivers/iommu/intel/irq_remapping.c
+++ b/drivers/iommu/intel/irq_remapping.c
@@ -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;