KVM: arm64: Define constant value for ICC_SRE_EL2

Move the bag of bits defining the value of ICC_SRE_EL2 to a common
spot so that it can be reused by the save/restore code.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20250714122634.3334816-4-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

Author: Marc Zyngier

arch/arm64/kvm/sys_regs.c

@@ -532,8 +532,7 @@ static bool access_gic_sre(struct kvm_vcpu *vcpu,
 		return ignore_write(vcpu, p);
 
 	if (p->Op1 == 4) {	/* ICC_SRE_EL2 */
-		p->regval = (ICC_SRE_EL2_ENABLE | ICC_SRE_EL2_SRE |
-			     ICC_SRE_EL1_DIB | ICC_SRE_EL1_DFB);
+		p->regval = KVM_ICC_SRE_EL2;
 	} else {		/* ICC_SRE_EL1 */
 		p->regval = vcpu->arch.vgic_cpu.vgic_v3.vgic_sre;
 	}

arch/arm64/kvm/vgic/vgic.h

@@ -64,6 +64,9 @@
 				      KVM_REG_ARM_VGIC_SYSREG_CRM_MASK | \
 				      KVM_REG_ARM_VGIC_SYSREG_OP2_MASK)
 
+#define KVM_ICC_SRE_EL2		(ICC_SRE_EL2_ENABLE | ICC_SRE_EL2_SRE |	\
+				 ICC_SRE_EL1_DIB | ICC_SRE_EL1_DFB)
+
 /*
  * As per Documentation/virt/kvm/devices/arm-vgic-its.rst,
  * below macros are defined for ITS table entry encoding.