[PATCH] arm/vgic-v2: Fix undefined behavior in vgic_fetch_itargetsr() The current implementation performs left shift operations that may trigger undefined behavior when the target value is too large. This patch:

[Jahan Murudi]

1. Changes the shift from signed (1) to unsigned (1U) to ensure well-defined
   behavior for all valid target values
2. Maintains identical functionality while fixing the UBSAN warning

The issue was detected by UBSAN:
(XEN) UBSAN: Undefined behaviour in arch/arm/vgic-v2.c:73:56
(XEN) left shift of 128 by 24 places cannot be represented in type 'int'
(XEN) Xen WARN at common/ubsan/ubsan.c:174

Signed-off-by: Jahan Murudi <jahan.murudi...@renesas.com>
---
 xen/arch/arm/vgic-v2.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/arm/vgic-v2.c b/xen/arch/arm/vgic-v2.c
index a19d610178..642407fd5b 100644
--- a/xen/arch/arm/vgic-v2.c
+++ b/xen/arch/arm/vgic-v2.c
@@ -70,7 +70,7 @@ static uint32_t vgic_fetch_itargetsr(struct vgic_irq_rank 
*rank,
     offset &= ~(NR_TARGETS_PER_ITARGETSR - 1);
 
     for ( i = 0; i < NR_TARGETS_PER_ITARGETSR; i++, offset++ )
-        reg |= (1 << read_atomic(&rank->vcpu[offset])) << (i * 
NR_BITS_PER_TARGET);
+        reg |= (1U << read_atomic(&rank->vcpu[offset])) << (i * 
NR_BITS_PER_TARGET);
 
     return reg;
 }
-- 
2.34.1