From: Carsten Otte <cotte@de.ibm.com>
To: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tossati <mtosatti@redhat.com>,
borntrae@linux.vnet.ibm.com, heicars2@linux.vnet.ibm.com,
mschwid2@linux.vnet.ibm.com, huckc@linux.vnet.ibm.com,
KVM <kvm@vger.kernel.org>,
Joachim von Buttlar <joachim_von_buttlar@de.ibm.com>,
Jens Freimann <jfrei@de.ibm.com>,
agraf@suse.de
Subject: Re: [patch 07/11] [PATCH] kvm-s390-ucontrol: interface to inject faults on a vcpu page table
Date: Wed, 04 Jan 2012 17:34:28 +0100 [thread overview]
Message-ID: <4F047F94.8050000@de.ibm.com> (raw)
In-Reply-To: <4F0479C7.4060500@de.ibm.com>
Avi wrote:
> There is an alternative, if you can recognize this condition exactly
> from the hardware fault, you can fault the lowcore yourself and retry.
> This eliminates a user interface. Is this workable?
I've read your comment again, and understood it this time. Trouble is
that the kernel cannot handle the situation either: userspace may need
to malloc some memory and call KVM_S390_UCAS_MAP prior to resolving it.
One could avoid the user interface by partially handling it in-kernel
and partially handling it in userspace without handshaking:
- user calls KVM_RUN
- SIE validity intercept
- kernel tries to gmap_fault and recognizes -EFAULT
- kernel returns validity intercept to user
- user does KVM_S390_UCAS_MAP
- user calls KVM_RUN
- SIE validity intercept
- kernel tries to gmap_fault and succeeds
- SIE runs ok
I guess I prefer to do processing of one operation in one place, and
thus I prefer the user interface over this. But yes, it'd be workable
without this interface. Is this what you want?
next prev parent reply other threads:[~2012-01-04 16:34 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-04 9:25 [patch 00/11] Ucontrol patchset respin without storage keys Carsten Otte
2012-01-04 9:25 ` [patch 01/11] [PATCH] kvm-s390: add parameter for KVM_CREATE_VM Carsten Otte
2012-01-04 9:25 ` [patch 02/11] [PATCH] kvm-s390-ucontrol: per vcpu address spaces Carsten Otte
2012-01-04 9:25 ` [patch 03/11] [PATCH] kvm-s390-ucontrol: export page faults to user Carsten Otte
2012-01-04 9:25 ` [patch 04/11] [PATCH] kvm-s390-ucontrol: export SIE control block " Carsten Otte
2012-01-04 9:25 ` [patch 05/11] [PATCH] kvm-s390-ucontrol: disable in-kernel handling of SIE intercepts Carsten Otte
2012-01-04 9:25 ` [patch 06/11] [PATCH] kvm-s390-ucontrol: disable in-kernel irq stack Carsten Otte
2012-01-04 9:25 ` [patch 07/11] [PATCH] kvm-s390-ucontrol: interface to inject faults on a vcpu page table Carsten Otte
2012-01-04 14:52 ` Avi Kivity
2012-01-04 16:09 ` Carsten Otte
2012-01-04 16:34 ` Carsten Otte [this message]
2012-01-04 17:25 ` Avi Kivity
2012-01-04 9:25 ` [patch 08/11] [PATCH] kvm-s390-ucontrol: disable sca Carsten Otte
2012-01-04 9:25 ` [patch 09/11] [PATCH] kvm-s390: fix assumption for KVM_MAX_VCPUS Carsten Otte
2012-01-04 9:25 ` [patch 10/11] [PATCH] kvm-s390-ucontrol: announce capability for user controlled vms Carsten Otte
2012-01-04 9:25 ` [patch 11/11] [PATCH] kvm-s390: Fix return code for unknown ioctl numbers Carsten Otte
2012-01-04 14:54 ` [patch 00/11] Ucontrol patchset respin without storage keys Avi Kivity
2012-01-04 14:56 ` Avi Kivity
2012-01-05 13:41 ` Marcelo Tosatti
2012-01-05 13:47 ` Marcelo Tosatti
2012-01-05 15:24 ` Carsten Otte
2012-01-09 12:19 ` Marcelo Tosatti
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