From: Gleb Natapov <gleb@redhat.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
kvm@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, avi@redhat.com, mingo@elte.hu,
tglx@linutronix.de, riel@redhat.com, cl@linux-foundation.org
Subject: Re: [PATCH v3 04/12] Add "handle page fault" PV helper.
Date: Wed, 20 Jan 2010 12:02:54 +0200 [thread overview]
Message-ID: <20100120100254.GC5238@redhat.com> (raw)
In-Reply-To: <4B5611A9.4050301@zytor.com>
On Tue, Jan 19, 2010 at 12:10:17PM -0800, H. Peter Anvin wrote:
> On 01/19/2010 09:44 AM, Gleb Natapov wrote:
> >
> > Yes it can be done this way and I'll look into it once more. Using
> > exception vector is more convenient for three reasons: it allows to pass
> > additional data in error code, it doesn't require guest to issue EOI,
> > exception can be injected when interrupts are disabled by a guest. The
> > last one is not important for now since host doesn't inject notifications
> > when interrupts are disabled currently. Having Intel allocate one
> > exception vector for hypervisor use would be really nice though.
> >
>
> That's probably not going to happen, for the rather obvious reason: *you
> already have 224 of them*.
>
> You seem to be thinking here that vectors 0-31 have to be exceptions and
> 32-255 have to be interrupts. *There is no such distinction*; the only
> thing special about 0-31 is that we (Intel) reserve the right to control
> the assignments; for 32-255 the platform and OS control the assignment.
>
I would be glad to interpret the spec like you do, but table 6-1 SDM 3A
mark vectors 2,32-255 as interrupts while others are traps, fault and
aborts. Unfortunately VMX designers seems to be interpreting the spec
like I do. See below.
> You can have the guest OS take an exception on a vector above 31 just
> fine; you just need it to tell the hypervisor which vector it, the OS,
> assigned for this purpose.
>
VMX doesn't allow to inject hardware exception with vector greater then 31.
SDM 3B section 23.2.1.3.
I can inject the event as HW interrupt on vector greater then 32 but not
go through APIC so EOI will not be required. This sounds non-architectural
and I am not sure kernel has entry point code for this kind of event, it
has one for exception and one for interrupts that goes through __do_IRQ()
which assumes that interrupts should be ACKed.
--
Gleb.
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next prev parent reply other threads:[~2010-01-20 10:03 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-05 14:12 [PATCH v3 00/12] KVM: Add host swap event notifications for PV guest Gleb Natapov
2010-01-05 14:12 ` [PATCH v3 01/12] Move kvm_smp_prepare_boot_cpu() from kvmclock.c to kvm.c Gleb Natapov
2010-01-05 14:12 ` [PATCH v3 02/12] Add PV MSR to enable asynchronous page faults delivery Gleb Natapov
2010-01-05 14:12 ` [PATCH v3 03/12] Add async PF initialization to PV guest Gleb Natapov
2010-01-05 14:12 ` [PATCH v3 04/12] Add "handle page fault" PV helper Gleb Natapov
2010-01-14 17:31 ` Peter Zijlstra
2010-01-17 14:44 ` Gleb Natapov
2010-01-17 15:09 ` Peter Zijlstra
2010-01-17 15:12 ` Gleb Natapov
2010-01-18 9:53 ` Andi Kleen
2010-01-18 8:34 ` H. Peter Anvin
2010-01-18 8:50 ` Gleb Natapov
2010-01-19 1:53 ` H. Peter Anvin
2010-01-19 6:55 ` Gleb Natapov
2010-01-19 17:03 ` H. Peter Anvin
2010-01-19 17:44 ` Gleb Natapov
2010-01-19 20:10 ` H. Peter Anvin
2010-01-20 10:02 ` Gleb Natapov [this message]
2010-01-20 12:00 ` Avi Kivity
2010-01-20 17:18 ` Rik van Riel
2010-01-21 8:56 ` Avi Kivity
2010-01-20 18:45 ` H. Peter Anvin
2010-01-21 8:58 ` Avi Kivity
2010-01-20 17:43 ` H. Peter Anvin
2010-01-21 9:02 ` Avi Kivity
2010-01-21 9:04 ` Gleb Natapov
2010-01-21 9:05 ` Avi Kivity
2010-01-21 15:47 ` H. Peter Anvin
2010-01-22 7:25 ` Gleb Natapov
2010-01-05 14:12 ` [PATCH v3 05/12] Export __get_user_pages_fast Gleb Natapov
2010-01-17 15:46 ` Christoph Hellwig
2010-01-05 14:12 ` [PATCH v3 06/12] Add get_user_pages() variant that fails if major fault is required Gleb Natapov
2010-01-17 15:43 ` Christoph Hellwig
2010-01-05 14:12 ` [PATCH v3 07/12] Maintain memslot version number Gleb Natapov
2010-01-05 14:12 ` [PATCH v3 08/12] Inject asynchronous page fault into a guest if page is swapped out Gleb Natapov
2010-01-05 14:12 ` [PATCH v3 09/12] Retry fault before vmentry Gleb Natapov
2010-01-05 14:12 ` [PATCH v3 10/12] Handle async PF in non preemptable context Gleb Natapov
2010-01-05 14:12 ` [PATCH v3 11/12] Let host know whether the guest can handle async PF in non-userspace context Gleb Natapov
2010-01-05 14:12 ` [PATCH v3 12/12] Send async PF when guest is not in userspace too Gleb Natapov
2010-01-05 15:05 ` [PATCH v3 00/12] KVM: Add host swap event notifications for PV guest Jun Koi
2010-01-05 15:59 ` Rik van Riel
2010-01-05 16:04 ` Avi Kivity
2010-01-06 10:17 ` Jun Koi
2010-01-06 10:21 ` Gleb Natapov
2010-01-08 16:18 ` Marcelo Tosatti
2010-01-08 16:47 ` Gleb Natapov
2010-01-08 19:24 ` Rik van Riel
2010-01-08 19:30 ` Bryan Donlan
2010-01-08 19:55 ` Rik van Riel
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