Re: [PATCH 1/1] KVM: s390: fix LPSWEY handling

Claudio Imbrenda
2024-06-28T15:26:47Z

On Fri, 28 Jun 2024 16:53:20 +0200
Christian Borntraeger <borntraeger@linux.ibm.com> wrote:

> Am 27.06.24 um 11:57 schrieb Heiko Carstens:
> > On Thu, Jun 27, 2024 at 11:05:20AM +0200, Christian Borntraeger wrote:
> >> in rare cases, e.g. for injecting a machine check we do intercept all
> >> load PSW instructions via ICTL_LPSW. With facility 193 a new variant
> >> LPSWEY was added. KVM needs to handle that as well.
> >>
> >> Fixes: a3efa8429266 ("KVM: s390: gen_facilities: allow facilities 165, 193, 194 and 196")
> >> Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com>
> >> Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
> >> ---
> >> arch/s390/include/asm/kvm_host.h | 1 +
> >> arch/s390/kvm/kvm-s390.c | 1 +
> >> arch/s390/kvm/kvm-s390.h | 16 ++++++++++++++++
> >> arch/s390/kvm/priv.c | 32 ++++++++++++++++++++++++++++++++
> >> 4 files changed, 50 insertions(+)
> >
> > ...
> >
> >> +static inline u64 kvm_s390_get_base_disp_siy(struct kvm_vcpu *vcpu, u8 *ar)
> >> +{
> >> + u32 base1 = vcpu->arch.sie_block->ipb >> 28;
> >> + u32 disp1 = ((vcpu->arch.sie_block->ipb & 0x0fff0000) >> 16) +

long disp1 = ...

> >> + ((vcpu->arch.sie_block->ipb & 0xff00) << 4);
> >> +
> >> + /* The displacement is a 20bit _SIGNED_ value */
> >> + if (disp1 & 0x80000)
> >> + disp1+=0xfff00000;

disp1 = sign_extend64(disp1, 20);

> >> +
> >> + if (ar)
> >> + *ar = base1;
> >> +
> >> + return (base1 ? vcpu->run->s.regs.gprs[base1] : 0) + (long)(int)disp1;

+ disp1;

> >> +}
> >
> > You may want to use sign_extend32() or sign_extend64() instead of open-coding.
>
> Something like sign_extend64(disp1, 31)
> I actually find that harder to read, but I am open for other opinions.

I think what he meant is what I wrote above, but it doesn't matter too
much.

with or without the above improvements:

Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>