Re: [PATCH v2 2/2] s390/kvm: VSIE: fix MVPG handling for prefixing and MSO

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

On Tue, 23 Mar 2021 16:16:18 +0100
Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> On 23.03.21 16:11, David Hildenbrand wrote:
> > On 23.03.21 16:07, Christian Borntraeger wrote:  
> >>
> >>
> >> On 22.03.21 15:05, Claudio Imbrenda wrote:  
> >>> Prefixing needs to be applied to the guest real address to
> >>> translate it into a guest absolute address.
> >>>
> >>> The value of MSO needs to be added to a guest-absolute address in
> >>> order to obtain the host-virtual.
> >>>
> >>> Fixes: 223ea46de9e79 ("s390/kvm: VSIE: correctly handle MVPG when
> >>> in VSIE") Cc: stable@vger.kernel.org
> >>> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> >>> Reported-by: Janosch Frank <frankja@linux.ibm.com>
> >>> ---
> >>>    arch/s390/kvm/vsie.c | 6 +++++-
> >>>    1 file changed, 5 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
> >>> index 48aab6290a77..ac86f11e46dc 100644
> >>> --- a/arch/s390/kvm/vsie.c
> >>> +++ b/arch/s390/kvm/vsie.c
> >>> @@ -1002,7 +1002,7 @@ static u64 vsie_get_register(struct
> >>> kvm_vcpu *vcpu, struct vsie_page *vsie_page, static int
> >>> vsie_handle_mvpg(struct kvm_vcpu *vcpu, struct vsie_page
> >>> *vsie_page) { struct kvm_s390_sie_block *scb_s =
> >>> &vsie_page->scb_s;
> >>> -    unsigned long pei_dest, pei_src, src, dest, mask;
> >>> +    unsigned long pei_dest, pei_src, dest, src, mask, mso,
> >>> prefix; u64 *pei_block = &vsie_page->scb_o->mcic;
> >>>        int edat, rc_dest, rc_src;
> >>>        union ctlreg0 cr0;
> >>> @@ -1010,9 +1010,13 @@ static int vsie_handle_mvpg(struct
> >>> kvm_vcpu *vcpu, struct vsie_page *vsie_page) cr0.val =
> >>> vcpu->arch.sie_block->gcr[0]; edat = cr0.edat &&
> >>> test_kvm_facility(vcpu->kvm, 8); mask =
> >>> _kvm_s390_logical_to_effective(&scb_s->gpsw, PAGE_MASK);
> >>> +    mso = scb_s->mso & ~(1UL << 20);  
> >>             shouldnt that be ~((1UL << 20 ) -1)

oops

> > 
> > Looking at shadow_scb(), we can simply take scb_s->mso unmodified.  
> 
> Right, I think I can fix this up (and get rid of the local mso

I think that's easier/simpler

> variable) when queueing. Or shall Claudio send a new version of the
> patch?