[xen staging] xen/arm: gic: implement helper functions for INTID checks

[patchbot@xxxxxxx]

commit c2c23ee8db3a6ce4d4d4dfe9b2fd38f898342eea
Author:     Leonid Komarianskyi <Leonid_Komarianskyi@xxxxxxxx>
AuthorDate: Tue Sep 9 10:08:59 2025 +0000
Commit:     Stefano Stabellini <stefano.stabellini@xxxxxxx>
CommitDate: Tue Sep 9 16:31:51 2025 -0700

    xen/arm: gic: implement helper functions for INTID checks
    
    Introduced two new helper functions: gic_is_valid_line and
    gic_is_spi. The first function helps determine whether an IRQ
    number is less than the number of lines supported by hardware. The
    second function additionally checks if the IRQ number falls within the
    SPI range. Also, updated the appropriate checks to use these new helper
    functions.
    
    The current checks for the real GIC are very similar to those for the
    vGIC but serve a different purpose. For GIC-related code, the interrupt
    numbers should be validated based on whether the hardware can operate
    with such interrupts. On the other hand, for the vGIC, the indexes must
    also be verified to ensure they are available for a specific domain. The
    first reason for introducing these helper functions is to avoid
    potential confusion with vGIC-related checks. The second reason is to
    consolidate similar code into separate functions, which can be more
    easily extended by additional conditions, e.g., when implementing
    extended SPI interrupts.
    
    The changes, which replace open-coded checks with the use of the new
    helper functions, do not introduce any functional changes, as the helper
    functions follow the current IRQ index verification logic.
    
    Signed-off-by: Leonid Komarianskyi <leonid_komarianskyi@xxxxxxxx>
    Reviewed-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>
    Acked-by: Julien Grall <jgrall@xxxxxxxxxx>
---
 xen/arch/arm/gic.c             | 3 ++-
 xen/arch/arm/include/asm/gic.h | 9 +++++++++
 xen/arch/arm/irq.c             | 2 +-
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
index e80fe0ca24..4bb11960ee 100644
--- a/xen/arch/arm/gic.c
+++ b/xen/arch/arm/gic.c
@@ -111,7 +111,8 @@ static void gic_set_irq_priority(struct irq_desc *desc, 
unsigned int priority)
 void gic_route_irq_to_xen(struct irq_desc *desc, unsigned int priority)
 {
     ASSERT(priority <= 0xff);     /* Only 8 bits of priority */
-    ASSERT(desc->irq < gic_number_lines());/* Can't route interrupts that 
don't exist */
+    /* Can't route interrupts that don't exist */
+    ASSERT(gic_is_valid_line(desc->irq));
     ASSERT(test_bit(_IRQ_DISABLED, &desc->status));
     ASSERT(spin_is_locked(&desc->lock));
 
diff --git a/xen/arch/arm/include/asm/gic.h b/xen/arch/arm/include/asm/gic.h
index 541f0eeb80..3fcee42675 100644
--- a/xen/arch/arm/include/asm/gic.h
+++ b/xen/arch/arm/include/asm/gic.h
@@ -306,6 +306,15 @@ extern void gic_dump_vgic_info(struct vcpu *v);
 
 /* Number of interrupt lines */
 extern unsigned int gic_number_lines(void);
+static inline bool gic_is_valid_line(unsigned int irq)
+{
+    return irq < gic_number_lines();
+}
+
+static inline bool gic_is_spi(unsigned int irq)
+{
+    return irq >= NR_LOCAL_IRQS && gic_is_valid_line(irq);
+}
 
 /* IRQ translation function for the device tree */
 int gic_irq_xlate(const u32 *intspec, unsigned int intsize,
diff --git a/xen/arch/arm/irq.c b/xen/arch/arm/irq.c
index 02ca82c089..29524e5d53 100644
--- a/xen/arch/arm/irq.c
+++ b/xen/arch/arm/irq.c
@@ -418,7 +418,7 @@ err:
 bool is_assignable_irq(unsigned int irq)
 {
     /* For now, we can only route SPIs to the guest */
-    return (irq >= NR_LOCAL_IRQS) && (irq < gic_number_lines());
+    return gic_is_spi(irq);
 }
 
 /*
--
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