From: james.morse@arm•com (James Morse)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v4 00/21] SError rework + RAS&IESB for firmware first support
Date: Tue, 14 Nov 2017 16:11:03 +0000 [thread overview]
Message-ID: <5A0B1597.3030809@arm.com> (raw)
In-Reply-To: <20171113161445.xfqyuntza76ckdmq@hawk.localdomain>
Hi Drew,
On 13/11/17 16:14, Andrew Jones wrote:
> On Mon, Nov 13, 2017 at 12:29:46PM +0100, Christoffer Dall wrote:
>> On Thu, Nov 09, 2017 at 06:14:56PM +0000, James Morse wrote:
>>> On 19/10/17 15:57, James Morse wrote:
>>>> Known issues:
>>>> * KVM-Migration: VDISR_EL2 is exposed to userspace as DISR_EL1, but how should
>>>> HCR_EL2.VSE or VSESR_EL2 be migrated when the guest has an SError pending but
>>>> hasn't taken it yet...?
>>>
>>> I've been trying to work out how this pending-SError-migration could work.
[..]
>>> To get out of this corner: why not declare pending-SError-migration an invalid
>>> thing to do?
>>
>> To answer that question we'd have to know if that is generally a valid
>> thing to require. How will higher level tools in the stack deal with
>> this (e.g. libvirt, and OpenStack). Is it really valid to tell them
>> "nope, can't migrate right now". I'm thinking if you have a failing
>> host and want to signal some error to the guest, that's probably a
>> really good time to migrate your mission-critical VM away to a different
>> host, and being told, "sorry, cannot do this" would be painful. I'm
>> cc'ing Drew for his insight into libvirt and how this is done on x86,
>> but I'm not really crazy about this idea.
> Without actually confirming, I'm pretty sure it's handled with a best
> effort to cancel the migration, continuing/restoring execution on the
> source host (or there may be other policies that could be set as well).
> Naturally, if the source host is going down and the migration is
> cancelled, then the VM goes down too...
> Anyway, I don't think we would generally want to introduce guest
> controlled migration blockers. IIUC, this migration blocker would remain
> until the guest handled the SError, which it may never unmask.
Yes, given the guest can influence this it needs exposing so it can be migrated.
[...]
>> My suggestion would be to add some set of VCPU exception state,
>> potentially as flags, which can be migrated along with the VM, or at
>> least used by userspace to query the state of the VM, if there exists a
>> reliable mechanism to restore the state again without any side effects.
>>
>> I think we have to comb through Documentation/virtual/kvm/api.txt to see
>> if we can reuse anything, and if not, add something. We could also
>
> Maybe KVM_GET/SET_VCPU_EVENTS? Looks like the doc mistakenly states it's
> a VM ioctl, but it's a VCPU ioctl.
Hmm, if I suppress my register-size pedantry we can put the lower 32 bits of
VSESR_EL2 in exception.error_code and use has_error_code to mark it valid.
'exception' in this struct ends up meaning SError on arm64.
(While VSESR_EL2 is 64bit[0], the value gets written into the ESR, which is
32bit, so I doubt the top 32bits can be used, currently they are all reserved.)
I'll go dig into how x86 uses this...
Thanks!
James
[0]
https://static.docs.arm.com/ddi0587/a/RAS%20Extension-release%20candidate_march_29.pdf
next prev parent reply other threads:[~2017-11-14 16:11 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-19 14:57 [PATCH v4 00/21] SError rework + RAS&IESB for firmware first support James Morse
2017-10-19 14:57 ` [PATCH v4 01/21] arm64: explicitly mask all exceptions James Morse
2017-10-19 14:57 ` [PATCH v4 02/21] arm64: introduce an order for exceptions James Morse
2017-10-19 14:57 ` [PATCH v4 03/21] arm64: Move the async/fiq helpers to explicitly set process context flags James Morse
2017-10-19 14:57 ` [PATCH v4 04/21] arm64: Mask all exceptions during kernel_exit James Morse
2017-10-19 14:57 ` [PATCH v4 05/21] arm64: entry.S: Remove disable_dbg James Morse
2017-10-19 14:57 ` [PATCH v4 06/21] arm64: entry.S: convert el1_sync James Morse
2017-10-19 14:57 ` [PATCH v4 07/21] arm64: entry.S convert el0_sync James Morse
2017-10-19 14:57 ` [PATCH v4 08/21] arm64: entry.S: convert elX_irq James Morse
2017-10-19 14:57 ` [PATCH v4 09/21] KVM: arm/arm64: mask/unmask daif around VHE guests James Morse
2017-10-30 7:40 ` Christoffer Dall
2017-11-02 12:14 ` James Morse
2017-11-03 12:45 ` Christoffer Dall
2017-11-03 17:19 ` James Morse
2017-11-06 12:42 ` Christoffer Dall
2017-10-19 14:57 ` [PATCH v4 10/21] arm64: entry.S: move SError handling into a C function for future expansion James Morse
2018-01-02 21:07 ` Adam Wallis
2018-01-03 16:00 ` James Morse
2017-10-19 14:57 ` [PATCH v4 11/21] arm64: cpufeature: Detect CPU RAS Extentions James Morse
2017-10-31 13:14 ` Will Deacon
2017-11-02 12:15 ` James Morse
2017-10-19 14:57 ` [PATCH v4 12/21] arm64: kernel: Survive corrected RAS errors notified by SError James Morse
2017-10-31 13:50 ` Will Deacon
2017-11-02 12:15 ` James Morse
2017-10-19 14:57 ` [PATCH v4 13/21] arm64: cpufeature: Enable IESB on exception entry/return for firmware-first James Morse
2017-10-31 13:56 ` Will Deacon
2017-10-19 14:58 ` [PATCH v4 14/21] arm64: kernel: Prepare for a DISR user James Morse
2017-10-19 14:58 ` [PATCH v4 15/21] KVM: arm64: Set an impdef ESR for Virtual-SError using VSESR_EL2 James Morse
2017-10-20 16:44 ` gengdongjiu
2017-10-23 15:26 ` James Morse
2017-10-24 9:53 ` gengdongjiu
2017-10-30 7:59 ` Christoffer Dall
2017-10-30 10:51 ` Christoffer Dall
2017-10-30 15:44 ` James Morse
2017-10-31 5:48 ` Christoffer Dall
2017-10-31 6:34 ` Marc Zyngier
2017-10-19 14:58 ` [PATCH v4 16/21] KVM: arm64: Save/Restore guest DISR_EL1 James Morse
2017-10-31 4:27 ` Marc Zyngier
2017-10-31 5:27 ` Christoffer Dall
2017-10-19 14:58 ` [PATCH v4 17/21] KVM: arm64: Save ESR_EL2 on guest SError James Morse
2017-10-31 4:26 ` Marc Zyngier
2017-10-31 5:47 ` Marc Zyngier
2017-11-01 17:42 ` James Morse
2017-10-19 14:58 ` [PATCH v4 18/21] KVM: arm64: Handle RAS SErrors from EL1 on guest exit James Morse
2017-10-31 5:55 ` Marc Zyngier
2017-10-31 5:56 ` Christoffer Dall
2017-10-19 14:58 ` [PATCH v4 19/21] KVM: arm64: Handle RAS SErrors from EL2 " James Morse
2017-10-27 6:26 ` gengdongjiu
2017-10-27 17:38 ` James Morse
2017-10-31 6:13 ` Marc Zyngier
2017-10-31 6:13 ` Christoffer Dall
2017-10-19 14:58 ` [PATCH v4 20/21] KVM: arm64: Take any host SError before entering the guest James Morse
2017-10-31 6:23 ` Christoffer Dall
2017-10-31 11:43 ` James Morse
2017-11-01 4:55 ` Christoffer Dall
2017-11-02 12:18 ` James Morse
2017-11-03 12:49 ` Christoffer Dall
2017-11-03 16:14 ` James Morse
2017-11-06 12:45 ` Christoffer Dall
2017-10-19 14:58 ` [PATCH v4 21/21] KVM: arm64: Trap RAS error registers and set HCR_EL2's TERR & TEA James Morse
2017-10-31 6:32 ` Christoffer Dall
2017-10-31 6:32 ` Marc Zyngier
2017-10-31 6:35 ` [PATCH v4 00/21] SError rework + RAS&IESB for firmware first support Christoffer Dall
2017-10-31 10:08 ` Will Deacon
2017-11-01 15:23 ` James Morse
2017-11-02 8:14 ` Christoffer Dall
2017-11-09 18:14 ` James Morse
2017-11-10 12:03 ` gengdongjiu
2017-11-13 11:29 ` Christoffer Dall
2017-11-13 13:05 ` Peter Maydell
2017-11-20 8:53 ` Christoffer Dall
2017-11-13 16:14 ` Andrew Jones
2017-11-13 17:56 ` Peter Maydell
2017-11-14 16:11 ` James Morse [this message]
2017-11-15 9:59 ` gengdongjiu
2017-11-14 16:03 ` James Morse
2017-11-15 9:15 ` gengdongjiu
2017-11-15 18:25 ` James Morse
2017-11-21 11:31 ` gengdongjiu
2017-11-20 8:55 ` Christoffer Dall
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