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    SubjectRe: [PATCH v10 01/26] KVM: s390: vsie: simulate VCPU SIE entry/exit
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    On 09/12/2018 09:42 PM, Tony Krowiak wrote:
    > From: David Hildenbrand <david@redhat.com>
    >
    > VCPU requests and VCPU blocking right now don't take care of the vSIE
    > (as it was not necessary until now). But we want to have synchronous VCPU
    > requests that will also be handled before running the vSIE again.
    >
    > So let's simulate a SIE entry of the VCPU when calling the sie during
    > vSIE handling and check for PROG_ flags. The existing infrastructure
    > (e.g. exit_sie()) will then detect that the SIE (in form of the vSIE) is
    > running and properly kick the vSIE CPU, resulting in it leaving the vSIE
    > loop and therefore the vSIE interception handler, allowing it to handle
    > VCPU requests.
    >
    > E.g. if we want to modify the crycb of the VCPU and make sure that any
    > masks also get applied to the VSIE crycb shadow (which uses masks from the
    > VCPU crycb), we will need a way to hinder the vSIE from running and make
    > sure to process the updated crycb before reentering the vSIE again.
    >
    > Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
    > Reviewed-by: Cornelia Huck <cohuck@redhat.com>
    > Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
    > Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
    > Signed-off-by: David Hildenbrand <david@redhat.com>

    I guess you should want to swap both signoffs? In the end they should show the
    patch flow.

    Other than that:
    Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>


    > ---
    > arch/s390/kvm/kvm-s390.c | 9 ++++++++-
    > arch/s390/kvm/kvm-s390.h | 1 +
    > arch/s390/kvm/vsie.c | 21 +++++++++++++++++----
    > 3 files changed, 26 insertions(+), 5 deletions(-)
    >
    > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
    > index f69333f..0b5aff0 100644
    > --- a/arch/s390/kvm/kvm-s390.c
    > +++ b/arch/s390/kvm/kvm-s390.c
    > @@ -2768,18 +2768,25 @@ static void kvm_s390_vcpu_request(struct kvm_vcpu *vcpu)
    > exit_sie(vcpu);
    > }
    >
    > +bool kvm_s390_vcpu_sie_inhibited(struct kvm_vcpu *vcpu)
    > +{
    > + return atomic_read(&vcpu->arch.sie_block->prog20) &
    > + (PROG_BLOCK_SIE | PROG_REQUEST);
    > +}
    > +
    > static void kvm_s390_vcpu_request_handled(struct kvm_vcpu *vcpu)
    > {
    > atomic_andnot(PROG_REQUEST, &vcpu->arch.sie_block->prog20);
    > }
    >
    > /*
    > - * Kick a guest cpu out of SIE and wait until SIE is not running.
    > + * Kick a guest cpu out of (v)SIE and wait until (v)SIE is not running.
    > * If the CPU is not running (e.g. waiting as idle) the function will
    > * return immediately. */
    > void exit_sie(struct kvm_vcpu *vcpu)
    > {
    > kvm_s390_set_cpuflags(vcpu, CPUSTAT_STOP_INT);
    > + kvm_s390_vsie_kick(vcpu);
    > while (vcpu->arch.sie_block->prog0c & PROG_IN_SIE)
    > cpu_relax();
    > }
    > diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
    > index 981e3ba..1f6e36c 100644
    > --- a/arch/s390/kvm/kvm-s390.h
    > +++ b/arch/s390/kvm/kvm-s390.h
    > @@ -290,6 +290,7 @@ void kvm_s390_set_tod_clock(struct kvm *kvm,
    > void kvm_s390_vcpu_stop(struct kvm_vcpu *vcpu);
    > void kvm_s390_vcpu_block(struct kvm_vcpu *vcpu);
    > void kvm_s390_vcpu_unblock(struct kvm_vcpu *vcpu);
    > +bool kvm_s390_vcpu_sie_inhibited(struct kvm_vcpu *vcpu);
    > void exit_sie(struct kvm_vcpu *vcpu);
    > void kvm_s390_sync_request(int req, struct kvm_vcpu *vcpu);
    > int kvm_s390_vcpu_setup_cmma(struct kvm_vcpu *vcpu);
    > diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
    > index a2b28cd..12b9707 100644
    > --- a/arch/s390/kvm/vsie.c
    > +++ b/arch/s390/kvm/vsie.c
    > @@ -830,7 +830,7 @@ static int do_vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
    > struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
    > struct kvm_s390_sie_block *scb_o = vsie_page->scb_o;
    > int guest_bp_isolation;
    > - int rc;
    > + int rc = 0;
    >
    > handle_last_fault(vcpu, vsie_page);
    >
    > @@ -858,7 +858,18 @@ static int do_vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
    > guest_enter_irqoff();
    > local_irq_enable();
    >
    > - rc = sie64a(scb_s, vcpu->run->s.regs.gprs);
    > + /*
    > + * Simulate a SIE entry of the VCPU (see sie64a), so VCPU blocking
    > + * and VCPU requests also hinder the vSIE from running and lead
    > + * to an immediate exit. kvm_s390_vsie_kick() has to be used to
    > + * also kick the vSIE.
    > + */
    > + vcpu->arch.sie_block->prog0c |= PROG_IN_SIE;
    > + barrier();
    > + if (!kvm_s390_vcpu_sie_inhibited(vcpu))
    > + rc = sie64a(scb_s, vcpu->run->s.regs.gprs);
    > + barrier();
    > + vcpu->arch.sie_block->prog0c &= ~PROG_IN_SIE;
    >
    > local_irq_disable();
    > guest_exit_irqoff();
    > @@ -1005,7 +1016,8 @@ static int vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
    > if (rc == -EAGAIN)
    > rc = 0;
    > if (rc || scb_s->icptcode || signal_pending(current) ||
    > - kvm_s390_vcpu_has_irq(vcpu, 0))
    > + kvm_s390_vcpu_has_irq(vcpu, 0) ||
    > + kvm_s390_vcpu_sie_inhibited(vcpu))
    > break;
    > }
    >
    > @@ -1122,7 +1134,8 @@ int kvm_s390_handle_vsie(struct kvm_vcpu *vcpu)
    > if (unlikely(scb_addr & 0x1ffUL))
    > return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
    >
    > - if (signal_pending(current) || kvm_s390_vcpu_has_irq(vcpu, 0))
    > + if (signal_pending(current) || kvm_s390_vcpu_has_irq(vcpu, 0) ||
    > + kvm_s390_vcpu_sie_inhibited(vcpu))
    > return 0;
    >
    > vsie_page = get_vsie_page(vcpu->kvm, scb_addr);
    >

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