From: "Jan Beulich" <JBeulich@suse.com>
To: george.dunlap@citrix.com, Paul Durrant <paul.durrant@citrix.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
Wei Liu <wei.liu2@citrix.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Tim Deegan <tim@xen.org>, Ian Jackson <Ian.Jackson@citrix.com>,
xen-devel <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH v14 4/9] iommu: don't domain_crash() inside iommu_map/unmap_page()
Date: Fri, 05 Oct 2018 05:17:37 -0600 [thread overview]
Message-ID: <5BB7485102000078001EEC83@prv1-mh.provo.novell.com> (raw)
In-Reply-To: <1b82387a547044979ec6eae55c271f81@AMSPEX02CL03.citrite.net>
>>> On 05.10.18 at 12:38, <Paul.Durrant@citrix.com> wrote:
>> From: George Dunlap
>> Sent: 05 October 2018 11:35
>>
>> > On Oct 5, 2018, at 11:27 AM, Paul Durrant <Paul.Durrant@citrix.com>
>> wrote:
>> > But for mapping too? It seems unnecessary to crash the domain in that
>> case.
>>
>> ISTR that the domain_crash() was added only a few years ago; I’d have to
>> go back and see the reasoning for it being added in the first place. I’ll
>> do that Monday if Jan doesn’t beat me to it.
>>
>
> I was added by the following commit:
>
> commit 834c97baebb3743c54bcae228e984ae1b9692e6a
> Author: Quan Xu <quan.xu@intel.com>
> Date: Tue Jun 14 15:10:57 2016 +0200
>
> IOMMU: handle IOMMU mapping and unmapping failures
>
> Treat IOMMU mapping and unmapping failures as a fatal to the DomU
> If IOMMU mapping and unmapping failed, crash the DomU and propagate
> the error up to the call trees.
>
> No spamming of the log can occur. For DomU, we avoid logging any
> message for already dying domains. For Dom0, that'll still be more
> verbose than we'd really like, but it at least wouldn't outright
> flood the console.
>
> Signed-off-by: Quan Xu <quan.xu@intel.com>
> Reviewed-by: Kevin Tian <kevin.tian@intel.com>
> Reviewed-by: Jan Beulich <jbeulich@suse.com>
>
> So the justification appears to be to avoid log spam.
Iirc that part of the description only exists because early version of
that patch did introduce log spam.
The problem iirc is mainly proper error handling, in particular proper
unwinding of earlier mappings that may have got installed
successfully in the context of the same hypercall (or whatever).
Jan
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next prev parent reply other threads:[~2018-10-05 11:17 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-04 10:45 [PATCH v14 0/9] paravirtual IOMMU pre-requisites and clean-up Paul Durrant
2018-10-04 10:45 ` [PATCH v14 1/9] iommu: introduce the concept of DFN Paul Durrant
2018-10-04 10:45 ` [PATCH v14 2/9] iommu: make use of type-safe DFN and MFN in exported functions Paul Durrant
2018-10-04 15:14 ` George Dunlap
2018-10-04 10:45 ` [PATCH v14 3/9] iommu: push use of type-safe DFN and MFN into iommu_ops Paul Durrant
2018-10-04 13:04 ` Paul Durrant
2018-10-04 13:07 ` Julien Grall
2018-10-04 10:45 ` [PATCH v14 4/9] iommu: don't domain_crash() inside iommu_map/unmap_page() Paul Durrant
2018-10-04 16:29 ` George Dunlap
2018-10-04 16:36 ` Paul Durrant
2018-10-05 7:33 ` Jan Beulich
2018-10-05 9:02 ` Paul Durrant
[not found] ` <F5DD545D-610B-40C7-827C-4CEAA2DF5F04@citrix.com>
[not found] ` <8B147463-7834-4525-AC10-36922338876F@citrix.com>
[not found] ` <b6add5ff3b6647eaab63265dbaf923bd@AMSPEX02CL03.citrite.net>
2018-10-05 10:31 ` Paul Durrant
[not found] ` <28341D09-548F-460C-8B22-43CA61EA1308@citrix.com>
2018-10-05 10:37 ` George Dunlap
2018-10-05 10:38 ` Paul Durrant
2018-10-05 11:17 ` Jan Beulich [this message]
2018-10-05 11:44 ` Paul Durrant
2018-10-04 10:45 ` [PATCH v14 5/9] memory: add check_get_page_from_gfn() as a wrapper Paul Durrant
2018-10-04 16:02 ` George Dunlap
2018-10-04 10:45 ` [PATCH v14 6/9] vtd: add missing check for shared EPT Paul Durrant
2018-10-04 10:45 ` [PATCH v14 7/9] vtd: add lookup_page method to iommu_ops Paul Durrant
2018-12-24 15:15 ` Andrew Cooper
2019-01-03 8:58 ` Paul Durrant
2018-10-04 10:45 ` [PATCH v14 8/9] mm / iommu: include need_iommu() test in iommu_use_hap_pt() Paul Durrant
2018-10-04 14:02 ` Jan Beulich
2018-10-04 16:23 ` George Dunlap
2018-10-05 16:03 ` Wei Liu
2018-10-05 16:13 ` Paul Durrant
2018-10-04 10:45 ` [PATCH v14 9/9] mm / iommu: split need_iommu() into has_iommu_pt() and need_iommu_pt_sync() Paul Durrant
2018-10-04 14:11 ` Jan Beulich
2018-10-04 16:23 ` George Dunlap
2018-10-04 17:15 ` Julien Grall
2018-10-05 14:50 ` Jan Beulich
2018-10-05 15:19 ` Paul Durrant
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