Messages in this thread | | | Subject | Re: [RFC PATCH v4 01/13] iommu: Introduce dirty log tracking framework | From | Keqian Zhu <> | Date | Fri, 14 May 2021 10:30:17 +0800 |
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On 2021/5/13 20:02, Lu Baolu wrote: > On 5/13/21 6:58 PM, Keqian Zhu wrote: >> >> >> On 2021/5/12 19:36, Lu Baolu wrote: >>> Hi keqian, >>> >>> On 5/12/21 4:44 PM, Keqian Zhu wrote: >>>> >>>> >>>> On 2021/5/12 11:20, Lu Baolu wrote: >>>>> On 5/11/21 3:40 PM, Keqian Zhu wrote: >>>>>>> For upper layers, before starting page tracking, they check the >>>>>>> dirty_page_trackable attribution of the domain and start it only it's >>>>>>> capable. Once the page tracking is switched on the vendor iommu driver >>>>>>> (or iommu core) should block further device attach/detach operations >>>>>>> until page tracking is stopped. >>>>>> But when a domain becomes capable after detaching a device, the upper layer >>>>>> still needs to query it and enable dirty log for it... >>>>>> >>>>>> To make things coordinated, maybe the upper layer can register a notifier, >>>>>> when the domain's capability change, the upper layer do not need to query, instead >>>>>> they just need to realize a callback, and do their specific policy in the callback. >>>>>> What do you think? >>>>>> >>>>> >>>>> That might be an option. But why not checking domain's attribution every >>>>> time a new tracking period is about to start? >>>> Hi Baolu, >>>> >>>> I'll add an attribution in iommu_domain, and the vendor iommu driver will update >>>> the attribution when attach/detach devices. >>>> >>>> The attribute should be protected by a lock, so the upper layer shouldn't access >>>> the attribute directly. Then the iommu_domain_support_dirty_log() still should be >>>> retained. Does this design looks good to you? >>> >>> Yes, that's what I was thinking of. But I am not sure whether it worth >>> of a lock here. It seems not to be a valid behavior for upper layer to >>> attach or detach any device while doing the dirty page tracking. >> Hi Baolu, >> >> Right, if the "detach|attach" interfaces and "dirty tracking" interfaces can be called concurrently, >> a lock in iommu_domain_support_dirty_log() is still not enough. I will add another note for the dirty >> tracking interfaces. >> >> Do you have other suggestions? I will accelerate the progress, so I plan to send out v5 next week. > > No further comments expect below nit: > > "iommu_switch_dirty_log: Perform actions to start|stop dirty log tracking" > > How about splitting it into > - iommu_start_dirty_log() > - iommu_stop_dirty_log() Yeah, actually this is my original version, and the "switch" style is suggested by Yi Sun. Anyway, I think both is OK, and the "switch" style can reduce some code.
Thanks, Keqian
> > Not a strong opinion anyway. > > Best regards, > baolu > . >
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