From: Alexander Graf <agraf@suse.de>
To: Avi Kivity <avi@redhat.com>
Cc: linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
kvm-ppc@vger.kernel.org, Milton Miller <miltonm@bga.com>,
KVM list <kvm@vger.kernel.org>
Subject: Re: [PATCH 26/26] KVM: PPC: Add Documentation about PV interface
Date: Mon, 28 Jun 2010 10:21:43 +0200 [thread overview]
Message-ID: <4330E5DC-63C5-40EA-9E99-34EE58074D1A@suse.de> (raw)
In-Reply-To: <4C285991.1050303@redhat.com>
On 28.06.2010, at 10:13, Avi Kivity wrote:
> On 06/28/2010 10:49 AM, Alexander Graf wrote:
>>=20
>>> I don't believe we support the kernel actually doing a syscall to =
itself
>>> anymore, at least on powerpc. The callers call the underlying =
system
>>> call function, or kernel_thread.
>>>=20
>>> That said, I would suggest we allocate a syscall number for this, as =
it
>>> would document the usage. (In additon to 0..nr_syscalls - 1 we have
>>> 0x1ebe in use).
>>> =20
>> That's actually a pretty good idea.
>> =20
>=20
> Since the syscall register is not architectual (or rather it is =
architectural but Linux ignores it) I don't see the point. It would =
work for Linux but may alias some random parameter for a different =
guest. We need a reliable method of distinguishing between syscalls and =
hypercalls. Matching pc would work (but is defeated by inlining) so =
long as we find some other way of identifying the hc pc to the =
hypervisor.
The other alternative I'd see is to reuse an instruction that is not sc. =
We could for example pull the mfpvr trick again, but pass a different =
magic value in the register this time that tells the hypervisor "this is =
a hypercall".
Or we could reserve a different SPR. But from what I've seen there are =
already quite a lot of SPRs out there. More than available numbers :).
The hypercall technique I used here is actually inspired by MOL. They =
use magic constants in r3 and r4 for their "OSI" identification. I'm =
frankly not sure what the best approach is, but considering that =
syscalls from the kernel lie in the guest kernel's hand, we could just =
declare any breakage a guest kernel bug.
Alex
next prev parent reply other threads:[~2010-06-28 8:21 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-25 23:24 [PATCH 00/26] KVM PPC PV framework Alexander Graf
2010-06-25 23:24 ` [PATCH 01/26] KVM: PPC: Introduce shared page Alexander Graf
2010-06-27 12:12 ` Avi Kivity
2010-06-29 9:54 ` Alexander Graf
2010-06-29 10:55 ` Avi Kivity
2010-06-25 23:24 ` [PATCH 02/26] KVM: PPC: Convert MSR to " Alexander Graf
2010-06-27 8:16 ` Avi Kivity
2010-06-27 9:38 ` Alexander Graf
2010-06-27 9:50 ` Avi Kivity
2010-06-27 10:40 ` Alexander Graf
2010-06-25 23:24 ` [PATCH 03/26] KVM: PPC: Convert DSISR " Alexander Graf
2010-06-25 23:24 ` [PATCH 04/26] KVM: PPC: Convert DAR " Alexander Graf
2010-06-25 23:24 ` [PATCH 05/26] KVM: PPC: Convert SRR0 and SRR1 " Alexander Graf
2010-06-25 23:24 ` [PATCH 06/26] KVM: PPC: Convert SPRG[0-4] " Alexander Graf
2010-06-25 23:24 ` [PATCH 07/26] KVM: PPC: Implement hypervisor interface Alexander Graf
2010-06-25 23:24 ` [PATCH 08/26] KVM: PPC: Add PV guest critical sections Alexander Graf
2010-06-27 8:21 ` Avi Kivity
2010-06-27 9:40 ` Alexander Graf
2010-06-27 9:52 ` Avi Kivity
2010-06-27 10:33 ` Alexander Graf
2010-06-27 10:59 ` Avi Kivity
2010-06-27 11:49 ` Alexander Graf
2010-06-27 11:53 ` Avi Kivity
2010-06-27 12:06 ` Alexander Graf
2010-06-27 22:03 ` Benjamin Herrenschmidt
2010-06-27 10:03 ` Avi Kivity
2010-06-27 10:35 ` Alexander Graf
2010-06-25 23:24 ` [PATCH 09/26] KVM: PPC: Add PV guest scratch registers Alexander Graf
2010-06-27 8:22 ` Avi Kivity
2010-06-27 9:41 ` Alexander Graf
2010-06-27 9:53 ` Avi Kivity
2010-06-25 23:24 ` [PATCH 10/26] KVM: PPC: Tell guest about pending interrupts Alexander Graf
2010-06-25 23:24 ` [PATCH 11/26] KVM: PPC: Make RMO a define Alexander Graf
2010-06-26 16:52 ` Segher Boessenkool
2010-06-27 9:08 ` Alexander Graf
2010-06-29 7:32 ` Segher Boessenkool
2010-06-29 7:39 ` Alexander Graf
2010-06-29 7:52 ` Segher Boessenkool
2010-06-29 8:04 ` Alexander Graf
2010-06-25 23:25 ` [PATCH 12/26] KVM: PPC: First magic page steps Alexander Graf
2010-06-27 8:24 ` Avi Kivity
2010-06-27 9:44 ` Alexander Graf
2010-06-25 23:25 ` [PATCH 13/26] KVM: PPC: Magic Page Book3s support Alexander Graf
2010-06-25 23:25 ` [PATCH 14/26] KVM: PPC: Magic Page BookE support Alexander Graf
2010-06-25 23:25 ` [PATCH 15/26] KVM: PPC: Expose magic page support to guest Alexander Graf
2010-06-25 23:25 ` [PATCH 16/26] KVM: Move kvm_guest_init out of generic code Alexander Graf
2010-06-25 23:25 ` [PATCH 17/26] KVM: PPC: Generic KVM PV guest support Alexander Graf
2010-06-25 23:25 ` [PATCH 18/26] KVM: PPC: KVM PV guest stubs Alexander Graf
2010-06-27 8:28 ` Avi Kivity
2010-06-27 9:47 ` Alexander Graf
2010-06-27 10:16 ` Avi Kivity
2010-06-27 10:38 ` Alexander Graf
2010-06-27 22:04 ` Benjamin Herrenschmidt
2010-06-28 4:39 ` Matt Evans
2010-06-28 6:33 ` Alexander Graf
2010-06-28 8:15 ` Avi Kivity
2010-06-28 8:23 ` Alexander Graf
2010-06-28 8:33 ` Avi Kivity
2010-06-25 23:25 ` [PATCH 19/26] KVM: PPC: PV instructions to loads and stores Alexander Graf
2010-06-25 23:25 ` [PATCH 20/26] KVM: PPC: PV tlbsync to nop Alexander Graf
2010-06-25 23:25 ` [PATCH 21/26] KVM: PPC: Introduce kvm_tmp framework Alexander Graf
2010-06-25 23:25 ` [PATCH 22/26] KVM: PPC: PV assembler helpers Alexander Graf
2010-06-25 23:25 ` [PATCH 23/26] KVM: PPC: PV mtmsrd L=1 Alexander Graf
2010-06-25 23:25 ` [PATCH 24/26] KVM: PPC: PV mtmsrd L=0 and mtmsr Alexander Graf
2010-06-26 17:03 ` Segher Boessenkool
2010-06-27 9:10 ` Alexander Graf
2010-06-29 7:37 ` Segher Boessenkool
2010-06-25 23:25 ` [PATCH 25/26] KVM: PPC: PV wrteei Alexander Graf
2010-06-25 23:25 ` [PATCH 26/26] KVM: PPC: Add Documentation about PV interface Alexander Graf
2010-06-27 8:14 ` Avi Kivity
2010-06-27 9:33 ` Alexander Graf
[not found] ` <4C270876.2050806%40redhat.com>
2010-06-28 7:18 ` Milton Miller
2010-06-28 7:49 ` Alexander Graf
2010-06-28 8:13 ` Avi Kivity
2010-06-28 8:21 ` Alexander Graf [this message]
2010-06-28 8:32 ` Avi Kivity
2010-06-27 8:34 ` Avi Kivity
2010-06-27 9:49 ` Alexander Graf
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