From: Avi Kivity <avi@redhat.com>
To: Alexander Graf <agraf@suse.de>
Cc: Scott Wood <scottwood@freescale.com>,
"linuxppc-dev@ozlabs.org" <linuxppc-dev@ozlabs.org>,
Paul Mackerras <paulus@samba.org>,
"kvm-ppc@vger.kernel.org" <kvm-ppc@vger.kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [RFC PATCH 17/17] KVM: PPC: Add an ioctl for userspace to select which platform to emulate
Date: Sun, 03 Jul 2011 11:15:18 +0300 [thread overview]
Message-ID: <4E102516.1040805@redhat.com> (raw)
In-Reply-To: <2EDDAC02-4BDC-4007-82E1-2C6D732C24D5@suse.de>
On 06/30/2011 07:33 PM, Alexander Graf wrote:
> On 30.06.2011, at 18:00, Avi Kivity<avi@redhat.com> wrote:
>
> > On 06/30/2011 06:22 PM, Alexander Graf wrote:
> >>> Regarding that. There's another option - the ioctl code embeds the structure size. So if we extend the ioctl parsing to pad up (or truncate down) from the user's size to our size, and similarly in the other direction, we can get away from this ugliness.
> >>>
> >>> Some years ago I posted a generic helper that did this (and also kmalloc'ed and kfree'd the data itself), but it wasn't received favourably. Maybe I should try again (and we can possibly use it in kvm even if it is rejected for general use, though that's against our principles of pushing all generic infrastructure to the wider kernel).
> >>
> >>
> >> That does sound interesting, but requires a lot more thought to be put into the actual code, as we basically need to read out the feature bitmap, then provide a minimum size for the chosen features and then decide if they fit in.
> >
> >
> > Why? just put the things you want in the structure.
> >
> > old userspace -> new kernel: we auto-zero the parts userspace left out, and zero means old behaviour, so everthing works
> > new userspace -> old kernel: truncate. Userspace shouldn't have used any new features (KVM_CAP), and we can -EINVAL if the truncated section contains a nonzero bit.
>
> Yup, which requires knowledge in the code on what actually fits :). Logic we don't have today.
I don't follow. What knowledge is required? Please give an example.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2011-07-03 8:15 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-29 10:15 [PATCH 0/17] Hypervisor-mode KVM on POWER7 and PPC970 Paul Mackerras
2011-06-29 10:16 ` [PATCH 01/17] KVM: PPC: Fix machine checks on 32-bit Book3S Paul Mackerras
2011-07-01 10:08 ` Alexander Graf
2011-06-29 10:17 ` [PATCH 02/17] KVM: PPC: Move fields between struct kvm_vcpu_arch and kvmppc_vcpu_book3s Paul Mackerras
2011-06-29 10:17 ` [PATCH 03/17] KVM: PPC: Split out code from book3s.c into book3s_pr.c Paul Mackerras
2011-06-29 10:18 ` [PATCH 04/17] powerpc, KVM: Rework KVM checks in first-level interrupt handlers Paul Mackerras
2011-06-29 10:18 ` [PATCH 05/17] KVM: PPC: Deliver program interrupts right away instead of queueing them Paul Mackerras
2011-07-01 11:47 ` Alexander Graf
2011-06-29 10:19 ` [PATCH 06/17] KVM: PPC: Pass init/destroy vm and prepare/commit memory region ops down Paul Mackerras
2011-06-29 10:19 ` [PATCH 07/17] KVM: PPC: Move guest enter/exit down into subarch-specific code Paul Mackerras
2011-06-29 10:20 ` [PATCH 08/17] powerpc: Set up LPCR for running guest partitions Paul Mackerras
2011-06-29 10:20 ` [PATCH 09/17] KVM: PPC: Split host-state fields out of kvmppc_book3s_shadow_vcpu Paul Mackerras
2011-06-29 10:21 ` [PATCH 10/17] KVM: PPC: Add support for Book3S processors in hypervisor mode Paul Mackerras
2011-07-01 18:37 ` Dave Hansen
2011-07-01 19:12 ` Alexander Graf
2011-07-04 11:51 ` Paul Mackerras
2011-06-29 10:22 ` [PATCH 11/17] KVM: PPC: Handle some PAPR hcalls in the kernel Paul Mackerras
2011-06-29 10:22 ` [PATCH 12/17] KVM: PPC: Accelerate H_PUT_TCE by implementing it in real mode Paul Mackerras
2011-06-29 10:23 ` [PATCH 13/17] KVM: PPC: Allow book3s_hv guests to use SMT processor modes Paul Mackerras
2012-04-16 9:45 ` Alexander Graf
2012-04-16 12:13 ` Paul Mackerras
2012-04-16 13:01 ` Alexander Graf
2011-06-29 10:25 ` [PATCH 14/17] KVM: PPC: Allocate RMAs (Real Mode Areas) at boot for use by guests Paul Mackerras
2011-06-29 10:26 ` [PATCH 15/17] powerpc, KVM: Split HVMODE_206 cpu feature bit into separate HV and architecture bits Paul Mackerras
2011-06-29 10:40 ` [PATCH 16/17] KVM: PPC: book3s_hv: Add support for PPC970-family processors Paul Mackerras
2011-06-29 10:41 ` [RFC PATCH 17/17] KVM: PPC: Add an ioctl for userspace to select which platform to emulate Paul Mackerras
2011-06-29 11:53 ` Josh Boyer
2011-06-29 11:56 ` Alexander Graf
2011-06-29 11:58 ` Josh Boyer
2011-06-30 8:34 ` Avi Kivity
2011-06-30 15:04 ` Alexander Graf
2011-06-30 15:16 ` Avi Kivity
2011-06-30 15:22 ` Alexander Graf
2011-06-30 16:00 ` Avi Kivity
2011-06-30 16:33 ` Alexander Graf
2011-07-03 8:15 ` Avi Kivity [this message]
2011-07-03 8:34 ` Alexander Graf
2011-07-03 8:56 ` Avi Kivity
2011-07-03 9:00 ` Alexander Graf
2011-07-03 9:05 ` Avi Kivity
2011-07-03 9:09 ` Alexander Graf
2011-07-03 9:12 ` Avi Kivity
2011-07-04 10:59 ` Alexander Graf
2011-07-04 11:22 ` Avi Kivity
2011-07-04 11:36 ` Alexander Graf
2011-07-04 11:37 ` Avi Kivity
2011-07-04 11:41 ` Alexander Graf
2011-06-30 23:13 ` Benjamin Herrenschmidt
2011-07-01 10:09 ` Paul Mackerras
2011-07-01 10:23 ` Alexander Graf
2011-07-01 18:24 ` [PATCH 0/17] Hypervisor-mode KVM on POWER7 and PPC970 Alexander Graf
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