[PATCH v2 03/10] KVM: PPC: Fix a mmio_host_swabbed uninitialized usage issue when VMX store

[wei.guo.simon at gmail.com]

From: Simon Guo <wei.guo.simon at gmail.com>

When KVM emulates VMX store, it will invoke kvmppc_get_vmx_data() to
retrieve VMX reg val. kvmppc_get_vmx_data() will check mmio_host_swabbed
to decide which double word of vr[] to be used. But the
mmio_host_swabbed can be uninitiazed during VMX store procedure:

kvmppc_emulate_loadstore
	\- kvmppc_handle_store128_by2x64
		\- kvmppc_get_vmx_data

So vcpu->arch.mmio_host_swabbed is not meant to be used at all for
emulation of store instructions, and this patch makes that true for
VMX stores. This patch also initializes mmio_host_swabbed to avoid
invisble trouble.

Signed-off-by: Simon Guo <wei.guo.simon at gmail.com>
---
 arch/powerpc/kvm/emulate_loadstore.c | 1 +
 arch/powerpc/kvm/powerpc.c           | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kvm/emulate_loadstore.c b/arch/powerpc/kvm/emulate_loadstore.c
index a382e15..b8a3aef 100644
--- a/arch/powerpc/kvm/emulate_loadstore.c
+++ b/arch/powerpc/kvm/emulate_loadstore.c
@@ -111,6 +111,7 @@ int kvmppc_emulate_loadstore(struct kvm_vcpu *vcpu)
 	vcpu->arch.mmio_sp64_extend = 0;
 	vcpu->arch.mmio_sign_extend = 0;
 	vcpu->arch.mmio_vmx_copy_nums = 0;
+	vcpu->arch.mmio_host_swabbed = 0;
 
 	switch (get_op(inst)) {
 	case 31:
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 4e38764..bef27b1 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -1374,7 +1374,7 @@ static inline int kvmppc_get_vmx_data(struct kvm_vcpu *vcpu, int rs, u64 *val)
 	if (di > 1)
 		return -1;
 
-	if (vcpu->arch.mmio_host_swabbed)
+	if (kvmppc_need_byteswap(vcpu))
 		di = 1 - di;
 
 	w0 = vrs.u[di * 2];
-- 
1.8.3.1