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KVM: PPC: Fix a mmio_host_swabbed uninitialized usage issue

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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 uninitialized 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
possible future problems.

Signed-off-by: Simon Guo <wei.guo.simon@gmail.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This commit is contained in:
Simon Guo 2018-05-07 14:20:09 +08:00 committed by Paul Mackerras
parent 173c520a04
commit f19d1f367a
2 changed files with 2 additions and 1 deletions
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1
arch/powerpc/kvm/emulate_loadstore.c
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@ -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:

2
arch/powerpc/kvm/powerpc.c
View file

@ -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];