Re: [ 17/53] s390/kvm: Fix store status for ACRS/FPRS

Jiri Slaby
2013-02-28T22:27:06Z

On 02/27/2013 12:57 AM, Greg Kroah-Hartman wrote:
> 3.0-stable review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: Christian Borntraeger <borntraeger@de.ibm.com>
>
> commit 15bc8d8457875f495c59d933b05770ba88d1eacb upstream.
>
> On store status we need to copy the current state of registers
> into a save area. Currently we might save stale versions:
> The sie state descriptor doesnt have fields for guest ACRS,FPRS,
> those registers are simply stored in the host registers. The host
> program must copy these away if needed. We do that in vcpu_put/load.
>
> If we now do a store status in KVM code between vcpu_put/load, the
> saved values are not up-to-date. Lets collect the ACRS/FPRS before
> saving them.
>
> This also fixes some strange problems with hotplug and virtio-ccw,
> since the low level machine check handler (on hotplug a machine check
> will happen) will revalidate all registers with the content of the
> save area.
>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Signed-off-by: Gleb Natapov <gleb@redhat.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>
> ---
> arch/s390/kvm/kvm-s390.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -584,6 +584,14 @@ int kvm_s390_vcpu_store_status(struct kv
> } else
> prefix = 0;
>
> + /*
> + * The guest FPRS and ACRS are in the host FPRS/ACRS due to the lazy
> + * copying in vcpu load/put. Lets update our copies before we save
> + * it into the save area
> + */
> + save_fp_regs(&vcpu->arch.guest_fpregs);
> + save_access_regs(vcpu->run->s.regs.acrs);

kvm_run structure does not have kvm_sync_regs in it in 3.0 yet. So this
fails with:
arch/s390/kvm/kvm-s390.c: In function 'kvm_s390_vcpu_store_status':
arch/s390/kvm/kvm-s390.c:593: error: 'struct kvm_run' has no member
named 's'

I believe the fix is just to remove save_access_regs, right?

thanks,
--
js
suse labs