xen/arm: vgic: implement helper functions for virq checks

Introduced two new helper functions for vGIC: vgic_is_valid_line and
vgic_is_spi. The functions are similar to the newly introduced
gic_is_valid_line and gic_is_spi, but they verify whether a vIRQ
is available for a specific domain, while GIC-specific functions
validate INTIDs for the real GIC hardware. For example, the GIC may
support all 992 SPI lines, but the domain may use only some part of them
(e.g., 640), depending on the highest IRQ number defined in the domain
configuration. Therefore, for vGIC-related code and checks, the
appropriate functions should be used. Also, updated the appropriate
checks to use these new helper functions.

The purpose of introducing new helper functions for vGIC is essentially
the same as for GIC: to avoid potential confusion with GIC-related
checks and to consolidate similar code into separate functions, which
can be more easily extended by additional conditions, e.g., when
implementing extended SPI interrupts.

Only the validation change in vgic_inject_irq may affect existing
functionality, as it currently checks whether the vIRQ is less than or
equal to vgic_num_irqs. Since IRQ indexes start from 0 (where 32 is the
first SPI), the check should behave consistently with similar logic in
other places and should check if the vIRQ number is less than
vgic_num_irqs. The remaining changes, which replace open-coded checks
with the use of these new helper functions, do not introduce any
functional changes, as the helper functions follow the current vIRQ
index verification logic.

Signed-off-by: Leonid Komarianskyi <leonid_komarianskyi@epam.com>
Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Reviewed-by: Volodymyr Babchuk <volodymyr_babchuk@epam.com>
Acked-by: Julien Grall <jgrall@amazon.com>

xen/arch/arm/gic.c

@@ -134,8 +134,7 @@ int gic_route_irq_to_guest(struct domain *d, unsigned int virq,
 
     ASSERT(spin_is_locked(&desc->lock));
     /* Caller has already checked that the IRQ is an SPI */
-    ASSERT(virq >= 32);
-    ASSERT(virq < vgic_num_irqs(d));
+    ASSERT(vgic_is_spi(d, virq));
     ASSERT(!is_lpi(virq));
 
     ret = vgic_connect_hw_irq(d, NULL, virq, desc, true);

xen/arch/arm/include/asm/vgic.h

@@ -335,6 +335,13 @@ extern void vgic_check_inflight_irqs_pending(struct vcpu *v,
 /* Default number of vGIC SPIs. 32 are substracted to cover local IRQs. */
 #define VGIC_DEF_NR_SPIS (min(gic_number_lines(), VGIC_MAX_IRQS) - 32)
 
+extern bool vgic_is_valid_line(struct domain *d, unsigned int virq);
+
+static inline bool vgic_is_spi(struct domain *d, unsigned int virq)
+{
+    return virq >= NR_LOCAL_IRQS && vgic_is_valid_line(d, virq);
+}
+
 /*
  * Allocate a guest VIRQ
  *  - spi == 0 => allocate a PPI. It will be the same on every vCPU

xen/arch/arm/irq.c

@@ -445,7 +445,7 @@ int route_irq_to_guest(struct domain *d, unsigned int virq,
     unsigned long flags;
     int retval = 0;
 
-    if ( virq >= vgic_num_irqs(d) )
+    if ( !vgic_is_valid_line(d, virq) )
     {
         printk(XENLOG_G_ERR
                "the vIRQ number %u is too high for domain %u (max = %u)\n",
@@ -563,7 +563,7 @@ int release_guest_irq(struct domain *d, unsigned int virq)
     int ret;
 
     /* Only SPIs are supported */
-    if ( virq < NR_LOCAL_IRQS || virq >= vgic_num_irqs(d) )
+    if ( !vgic_is_spi(d, virq) )
         return -EINVAL;
 
     desc = vgic_get_hw_irq_desc(d, NULL, virq);

xen/arch/arm/vgic.c

@@ -24,6 +24,12 @@
 #include <asm/gic.h>
 #include <asm/vgic.h>
 
+
+bool vgic_is_valid_line(struct domain *d, unsigned int virq)
+{
+    return virq < vgic_num_irqs(d);
+}
+
 static inline struct vgic_irq_rank *vgic_get_rank(struct vcpu *v,
                                                   unsigned int rank)
 {
@@ -582,7 +588,7 @@ void vgic_inject_irq(struct domain *d, struct vcpu *v, unsigned int virq,
     if ( !v )
     {
         /* The IRQ needs to be an SPI if no vCPU is specified. */
-        ASSERT(virq >= 32 && virq <= vgic_num_irqs(d));
+        ASSERT(vgic_is_spi(d, virq));
 
         v = vgic_get_target_vcpu(d->vcpu[0], virq);
     };
@@ -659,7 +665,7 @@ bool vgic_emulate(struct cpu_user_regs *regs, union hsr hsr)
 
 bool vgic_reserve_virq(struct domain *d, unsigned int virq)
 {
-    if ( virq >= vgic_num_irqs(d) )
+    if ( !vgic_is_valid_line(d, virq) )
         return false;
 
     return !test_and_set_bit(virq, d->arch.vgic.allocated_irqs);

xen/arch/arm/vgic/vgic.c

@@ -718,6 +718,11 @@ bool vgic_reserve_virq(struct domain *d, unsigned int virq)
     return !test_and_set_bit(virq, d->arch.vgic.allocated_irqs);
 }
 
+bool vgic_is_valid_line(struct domain *d, unsigned int virq)
+{
+    return virq < vgic_num_irqs(d);
+}
+
 int vgic_allocate_virq(struct domain *d, bool spi)
 {
     int first, end;