KVM: arm64: Check for SYSREGS_ON_CPU before accessing the 32bit state

Just like c6e35df ("KVM: arm64: Check for SYSREGS_ON_CPU before
accessing the CPU state") fixed the 64bit state access, add a check
for the 32bit state actually being on the CPU before writing it.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20250817121926.217900-2-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

Author: Marc Zyngier

arch/arm64/kvm/hyp/exception.c

@@ -59,15 +59,15 @@ static void __vcpu_write_spsr(struct kvm_vcpu *vcpu, unsigned long target_mode,
 
 static void __vcpu_write_spsr_abt(struct kvm_vcpu *vcpu, u64 val)
 {
-	if (has_vhe())
+	if (has_vhe() && vcpu_get_flag(vcpu, SYSREGS_ON_CPU))
 		write_sysreg(val, spsr_abt);
 	else
 		vcpu->arch.ctxt.spsr_abt = val;
 }
 
 static void __vcpu_write_spsr_und(struct kvm_vcpu *vcpu, u64 val)
 {
-	if (has_vhe())
+	if (has_vhe() && vcpu_get_flag(vcpu, SYSREGS_ON_CPU))
 		write_sysreg(val, spsr_und);
 	else
 		vcpu->arch.ctxt.spsr_und = val;