[PATCH 03/11] KVM: PPC: Fix a mmio_host_swabbed uninitialized usage issue when VMX store

[Simon Guo]

On Thu, May 03, 2018 at 03:48:26PM +1000, Paul Mackerras wrote:
> On Wed, Apr 25, 2018 at 07:54:36PM +0800, wei.guo.simon at gmail.com wrote:
> > 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
> > 
> > This patch corrects this by using kvmppc_need_byteswap() to choose
> > double word of vr[] and initialized mmio_host_swabbed to avoid invisble
> > trouble.
> > 
> > Signed-off-by: Simon Guo <wei.guo.simon at gmail.com>
> 
> The patch is correct, but I think the patch description needs to say
> that 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.
I will revise the commit message accordingly.

> 
> Paul.

Thanks,
- Simon