arm/arm64: KVM: PSCI: propagate caller endianness to the incoming vcpu

When booting a vcpu using PSCI, make sure we start it with the
endianness of the caller. Otherwise, secondaries can be pretty
unhappy to execute a BE kernel in LE mode...

This conforms to PSCI spec Rev B, 5.13.3.
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

arch/arm/include/asm/kvm_emulate.h

@@ -157,6 +157,11 @@ static inline u32 kvm_vcpu_hvc_get_imm(struct kvm_vcpu *vcpu)
 	return kvm_vcpu_get_hsr(vcpu) & HSR_HVC_IMM_MASK;
 }
 
+static inline void kvm_vcpu_set_be(struct kvm_vcpu *vcpu)
+{
+	*vcpu_cpsr(vcpu) |= PSR_E_BIT;
+}
+
 static inline bool kvm_vcpu_is_be(struct kvm_vcpu *vcpu)
 {
 	return !!(*vcpu_cpsr(vcpu) & PSR_E_BIT);

arch/arm/kvm/psci.c

@@ -62,6 +62,10 @@ static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
 		vcpu_set_thumb(vcpu);
 	}
 
+	/* Propagate caller endianness */
+	if (kvm_vcpu_is_be(source_vcpu))
+		kvm_vcpu_set_be(vcpu);
+
 	*vcpu_pc(vcpu) = target_pc;
 	vcpu->arch.pause = false;
 	smp_mb();		/* Make sure the above is visible */

arch/arm64/include/asm/kvm_emulate.h

@@ -177,6 +177,14 @@ static inline u8 kvm_vcpu_trap_get_fault(const struct kvm_vcpu *vcpu)
 	return kvm_vcpu_get_hsr(vcpu) & ESR_EL2_FSC_TYPE;
 }
 
+static inline void kvm_vcpu_set_be(struct kvm_vcpu *vcpu)
+{
+	if (vcpu_mode_is_32bit(vcpu))
+		*vcpu_cpsr(vcpu) |= COMPAT_PSR_E_BIT;
+	else
+		vcpu_sys_reg(vcpu, SCTLR_EL1) |= (1 << 25);
+}
+
 static inline bool kvm_vcpu_is_be(struct kvm_vcpu *vcpu)
 {
 	if (vcpu_mode_is_32bit(vcpu))