Re: [PATCH v3 1/2] KVM: s390: fix access register usage in ioctls

[Heiko Carstens <hca@linux.ibm.com>]

On Fri, Feb 16, 2024 at 10:36:15PM +0100, Eric Farman wrote:
> The routine ar_translation() can be reached by both the instruction
> intercept path (where the access registers had been loaded with the
> guest register contents), and the MEM_OP ioctls (which hadn't).
> Since this routine saves the current registers to vcpu->run,
> this routine erroneously saves host registers into the guest space.
> 
> Introduce a boolean in the kvm_vcpu_arch struct to indicate whether
> the registers contain guest contents. If they do (the instruction
> intercept path), the save can be performed and the AR translation
> is done just as it is today. If they don't (the MEM_OP path), the
> AR can be read from vcpu->run without stashing the current contents.
> 
> Signed-off-by: Eric Farman <farman@linux.ibm.com>
> ---
>  arch/s390/include/asm/kvm_host.h | 1 +
>  arch/s390/kvm/gaccess.c          | 3 ++-
>  arch/s390/kvm/kvm-s390.c         | 3 +++
>  3 files changed, 6 insertions(+), 1 deletion(-)

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>