Re: [PATCH v4 00/10] KVM: s390: make use of the GIB

Christian Borntraeger
2018-12-04T13:13:58Z

FWIW, Assuming that Michael addresses the small comments of Cornelia I will
apply the next version to kvms390/next. As we touch common s390/cio/ code
this will be a topic branch that I will merge. In case of conflicts Martin
can then also merge this. If there are no conflicts then this will only
go via the kvms390 tree.

On 30.11.2018 15:32, Michael Mueller wrote:
> The Guest Information Area (GIB) and its mechanics is part of
> the AIV facility. It provides hardware support to process
> Adapter Interruptions (AI) for pagable storage mode guests.
>
> Whenever a guest cannot process an AI because none of its
> vcpus is running in SIE context, a GIB alert interruption is
> sent to and handled by the host program to dispatch a vcpu of
> the respective guest.
>
> Eventually, the AI is handled by the guest.
>
> v3->v4:
> The central change of v4 is that the metric "vcpus_in_sie"
> has been dropped. A least agressive IAM restore strategy
> is being followed now. The consequence is that potentially
> more GAL interruptions are to be handled by the host program.
> The assuption as made that as soon the first vcpu is trying
> to go into wait state, this could be the last vcpu being
> open for I/O interruptions. Thus, to not loose the initiative
> to deliver I/O interruptions as soon as possible, the IAM
> is restored. Adding better heuristics can be done in future.
>
> I expect this to be the last version of the series.
>
> patch 01/12: Kernel msg now printed when FLIC fails
> to register during arch inititialization.
> patch 03/12: Commit message slightly changed with the
> hint that gib initialization is called
> by last patch of this serias.
> patch 09/12: IAM now restored during kvm_s390_handle_wait()
> patch 10/12: gib destroy case now handled upon unsuccessful
> arch inititialization.
>
> All other patches are unchanged.
>
> v2->v3:
> patch 01/12: Fixes a resource dealocation issue upon
> unsuccessful exit from kvm_arch_init().
> It is relevant for patch 11/12 as well.
> patch 08/12: The function process_gib_alert_list() has
> been rewritten to reduce the number of GAL
> interruptions on the host for many guest
> scenarios.
> patch 10/12: The IAM is now never cleared before SIE entry.
> It will be cleared by millicode as soon the
> first guest interruption is made pending and
> not directly processed in SIE. The IAM gets
> restored as soon a vm is idle, i.e. no vcpu
> of that guest is in SIE context anymore.
> patch 11/12: now integrates with new patch 01/12
> patch 12/12: This patch is just experimental and shall not
> be part of the final series.
>
> The first patch of series v2: "leave AIs in IPM of GISA
> during vcpu_pre_run()" has been dropped.
>
> All other patches are unchanged.
>
> v1->v2:
> patch 01/12: New patch. Tt can go also standalone without the
> rest of the GIB series presented here but is a
> requirement
> patch 03/12: kvm_s390_gib_init() now has a return code
> patch 06/12: unlink_gib_alert_list() now uses cmpxchg() instead
> of atomic_xchg()
> patch 08/12: New patch. Foctors out __find_vcpu_for_floating_irq()
> patch 09/12: process_gib_alert_list() has been simplified
> the GISA clear/destroy cases have been removed
> patch 11/12: kvm_s390_gisa_clear/destroy() now clear the IAM
> and process the alert list directly
> The IAM now gets restored in vcpu_post_run() only if
> the GISA is not in alert list
> patch 12/12: during kvm_arch_init() now the return code of
> kvm_s390_gib_init() is honored.
>
> All other patches are unchanged.
>
> Michael Mueller (10):
> KVM: s390: unregister debug feature on failing arch init
> s390/cio: add function chsc_sgib()
> KVM: s390: add the GIB and its related life-cyle functions
> KVM: s390: factor out nullify_gisa()
> KVM: s390: add kvm reference to struct sie_page2
> KVM: s390: factor out __find_vcpu_for_floating_irq()
> KVM: s390: add function process_gib_alert_list()
> KVM: s390: add functions to (un)register GISC with GISA
> KVM: s390: add and wire function gib_alert_irq_handler()
> KVM: s390: start using the GIB
>
> Documentation/kmsg/s390/kvm | 24 +++++
> arch/s390/include/asm/cio.h | 1 +
> arch/s390/include/asm/irq.h | 1 +
> arch/s390/include/asm/isc.h | 1 +
> arch/s390/include/asm/kvm_host.h | 19 +++-
> arch/s390/kernel/irq.c | 1 +
> arch/s390/kvm/interrupt.c | 214 +++++++++++++++++++++++++++++++++++++--
> arch/s390/kvm/kvm-s390.c | 27 ++++-
> arch/s390/kvm/kvm-s390.h | 7 ++
> drivers/s390/cio/chsc.c | 37 +++++++
> drivers/s390/cio/chsc.h | 1 +
> 11 files changed, 318 insertions(+), 15 deletions(-)
> create mode 100644 Documentation/kmsg/s390/kvm
>