From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cornelia Huck Subject: Re: [PATCH v2 09/12] KVM: s390: make kvm_s390_get_io_int() aware of GISA Date: Fri, 26 Jan 2018 10:41:51 +0100 Message-ID: <20180126104151.7cdfb156.cohuck@redhat.com> References: <20180125132848.175942-1-borntraeger@de.ibm.com> <20180125132848.175942-10-borntraeger@de.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: KVM , linux-s390 , Janosch Frank , David Hildenbrand , Martin Schwidefsky , Heiko Carstens , Michael Mueller To: Christian Borntraeger Return-path: Received: from mx1.redhat.com ([209.132.183.28]:43966 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752888AbeAZJl6 (ORCPT ); Fri, 26 Jan 2018 04:41:58 -0500 In-Reply-To: <20180125132848.175942-10-borntraeger@de.ibm.com> Sender: kvm-owner@vger.kernel.org List-ID: On Thu, 25 Jan 2018 14:28:45 +0100 Christian Borntraeger wrote: > From: Michael Mueller > > The function returns a pending I/O interrupt with the highest > priority defined by its ISC. > > Together with AIV activation, pending adapter interrupts are > managed by the GISA IPM. Thus kvm_s390_get_io_int() needs to > inspect the IPM as well when the interrupt with the highest > priority has to be identified. > > In case classic and adapter interrupts with the same ISC are > pending, the classic interrupt will be returned first. Can this lead to starving? Consider a guest that never enables itself for I/O interrupts, but collects pending interrupts via tpi. It will always get the intis for an isc, but not the ai, wouldn't it? > > Signed-off-by: Michael Mueller > Reviewed-by: Halil Pasic > Reviewed-by: Christian Borntraeger > Signed-off-by: Christian Borntraeger > --- > arch/s390/kvm/interrupt.c | 71 +++++++++++++++++++++++++++++++++++++++++++---- > 1 file changed, 65 insertions(+), 6 deletions(-)