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From: "'joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org'" <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
To: "Tian, Kevin" <kevin.tian-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Cc: "alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org"
	<alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	"rafael-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org"
	<rafael-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Jean-Philippe Brucker
	<jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org>,
	"gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org"
	<gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>,
	"will.deacon-5wv7dgnIgG8@public.gmane.org"
	<will.deacon-5wv7dgnIgG8@public.gmane.org>,
	"iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org"
	<iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>,
	Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>,
	"christian.koenig-5C7GfCeVMHo@public.gmane.org"
	<christian.koenig-5C7GfCeVMHo@public.gmane.org>
Subject: Re: [RFC PATCH 0/6] Auxiliary IOMMU domains and Arm SMMUv3
Date: Fri, 7 Dec 2018 11:29:26 +0100
Message-ID: <20181207102926.GM16835@8bytes.org> (raw)
In-Reply-To: <AADFC41AFE54684AB9EE6CBC0274A5D19BE689B8-0J0gbvR4kThpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>

Hi,

On Mon, Nov 26, 2018 at 07:29:45AM +0000, Tian, Kevin wrote:
> btw Baolu just reminded me one thing which is worthy of noting here.
> 'primary' vs. 'aux' concept makes sense only when we look from a device
> p.o.v. That binding relationship is not (*should not be*) carry-and-forwarded
> cross devices. every domain must be explicitly attached to other devices
> (instead of implicitly attached being above example), and new primary/aux
> attribute on another device will be decided at attach time.

Okay, so after all the discussions we had I learned a few more things
about the scalable mode feature and thought a bit longer about how to
best support it in the IOMMU-API.

The concept of sub-domains I initially proposed certainly makes no
sense, but scalable-mode specific attach/detach functions do. So instead
of a sub-domain mode, I'd like to propose device-feature sets.

The posted patch-set already includes this as device-attributes, but I
don't like this naming as we are really talking about additional
feature sets of a device. So how about we introduce this:

	enum iommu_dev_features {
		/* ... */
		IOMMU_DEV_FEAT_AUX,
		IOMMU_DEV_FEAT_SVA,
		/* ... */
	};

	/* Check if a device supports a given feature of the IOMMU-API */
	bool iommu_dev_has_feature(struct device *dev, enum iommu_dev_features *feat);

	/*
	 * Only works if iommu_dev_has_feature(dev, IOMMU_DEV_FEAT_AUX)
	 * returns true
	 *
	 * Also, as long as domains are attached to a device through
	 * this interface, any trys to call iommu_attach_device() should
	 * fail (iommu_detach_device() can't fail, so we fail on the
	 * tryint to re-attach). This should make us safe against a
	 * device being attached to a guest as a whole while there are
	 * still pasid users on it (aux and sva).
	 */
	int iommu_aux_attach_device(struct iommu_domain *domain,
				    struct device *dev);

	int iommu_aux_detach_device(struct iommu_domain *domain,
				    struct device *dev);
	/*
	 * I know we are targeting a system-wide pasid-space, so that
	 * the pasid would be the same for one domain on all devices,
	 * let's just keep the option open to have different
	 * pasid-spaces in one system. Also this way we can use it to
	 * check whether the domain is attached to this device at all.
	 *
	 * returns pasid or <0 if domain has no pasid on that device.
	 */
	int iommu_aux_get_pasid(struct iommu_domain *domain,
				struct device *dev);

	/* So we need a iommu_aux_detach_all()? */

This concept can also be easily extended for supporting SVA in parallel
on the same device, with the same constraints regarding the behavior of
iommu_attach_device()/iommu_detach_device().

So what do you think about that approach?

Regards,

	Joerg

	

  parent reply index

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-19 18:11 Jean-Philippe Brucker
     [not found] ` <20181019181158.2395-1-jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org>
2018-10-19 18:11   ` [RFC PATCH 1/6] iommu: Adapt attach/detach_dev() for auxiliary domains Jean-Philippe Brucker
     [not found]     ` <20181019181158.2395-2-jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org>
2018-10-22  2:32       ` Lu Baolu
2018-10-19 18:11   ` [RFC PATCH 2/6] drivers core: Add I/O ASID allocator Jean-Philippe Brucker
     [not found]     ` <20181019181158.2395-3-jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org>
2018-10-22  4:49       ` Lu Baolu
     [not found]         ` <9c6cd6c1-3569-4251-8344-fc9df0e743bc-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2018-10-22 10:22           ` Raj, Ashok
     [not found]             ` <20181022102254.GA25399-7RUrO8UaCDyr4tA6zuQqW9h3ngVCH38I@public.gmane.org>
2018-10-23  6:56               ` Lu Baolu
     [not found]                 ` <02006e4f-2acf-6ff8-b695-c54c99509b46-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2018-10-23 22:13                   ` Tian, Kevin
2018-11-07  4:53       ` Lu Baolu
     [not found]         ` <fb2bd5fe-5742-fcd8-b8f0-1885040e8d4f-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2018-11-08 18:51           ` Jean-Philippe Brucker
2018-11-12 14:40       ` Joerg Roedel
     [not found]         ` <20181112144039.GA25808-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2018-11-21 11:16           ` Jean-Philippe Brucker
     [not found]             ` <8f17757a-c657-aab9-a6a0-fb0cc9c610a8-5wv7dgnIgG8@public.gmane.org>
2018-11-21 19:10               ` Koenig, Christian
     [not found]                 ` <62f05552-df46-6e12-10ed-820429dfda59-5C7GfCeVMHo@public.gmane.org>
2018-11-22  6:59                   ` Tian, Kevin
2018-11-22  8:38                   ` Joerg Roedel
2018-11-22  8:44               ` Joerg Roedel
     [not found]                 ` <20181122084429.GB1586-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2018-11-22 11:17                   ` Jean-Philippe Brucker
2018-10-19 18:11   ` [RFC PATCH 3/6] iommu/sva: Use external PASID allocator Jean-Philippe Brucker
2018-10-19 18:11   ` [RFC PATCH 4/6] iommu/sva: Support AUXD feature Jean-Philippe Brucker
2018-10-19 18:11   ` [RFC PATCH 5/6] iommu/arm-smmu-v3: Implement detach_dev op Jean-Philippe Brucker
2018-10-19 18:11   ` [RFC PATCH 6/6] iommu/arm-smmu-v3: Add support for auxiliary domains Jean-Philippe Brucker
2018-10-20  3:36   ` [RFC PATCH 0/6] Auxiliary IOMMU domains and Arm SMMUv3 Xu Zaibo
2018-10-22  6:53   ` Tian, Kevin
     [not found]     ` <AADFC41AFE54684AB9EE6CBC0274A5D19BE0E176-0J0gbvR4kThpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2018-10-22 11:50       ` Robin Murphy
     [not found]         ` <11f88122-afd3-a34c-3cd4-db681bf5498b-5wv7dgnIgG8@public.gmane.org>
2018-10-22 15:35           ` Jordan Crouse
2018-10-22 18:01           ` Jean-Philippe Brucker
2018-11-06 16:25           ` joro-zLv9SwRftAIdnm+yROfE0A
     [not found]             ` <20181106162539.4gmkvg57mja3bn7k-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2018-11-07  3:40               ` Lu Baolu
     [not found]                 ` <e22e3631-2ecb-664d-5666-8e0f865dec83-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2018-11-07 16:43                   ` joro-zLv9SwRftAIdnm+yROfE0A
     [not found]                     ` <20181107164323.GA19831-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2018-11-07 17:23                       ` Alex Williamson
2018-11-21  4:40                       ` Lu Baolu
     [not found]                         ` <758bb120-5bc0-1e2d-ccd0-9be0bcc5d8bc-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2018-11-23 11:21                           ` joro-zLv9SwRftAIdnm+yROfE0A
     [not found]                             ` <20181123112125.GF1586-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2018-11-25  6:51                               ` Lu Baolu
2018-11-26  3:01                               ` Tian, Kevin
     [not found]                             ` <AADFC41AFE54684AB9EE6CBC0274A5D19BE68777@SHSMSX101.ccr.corp.intel.com>
     [not found]                               ` <AADFC41AFE54684AB9EE6CBC0274A5D19BE68777-0J0gbvR4kThpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2018-11-26  7:29                                 ` Tian, Kevin
     [not found]                                   ` <AADFC41AFE54684AB9EE6CBC0274A5D19BE689B8-0J0gbvR4kThpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2018-12-07 10:29                                     ` joro-zLv9SwRftAIdnm+yROfE0A [this message]
     [not found]                                       ` <20181207102926.GM16835-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2018-12-10  2:06                                         ` Tian, Kevin
     [not found]                                           ` <AADFC41AFE54684AB9EE6CBC0274A5D19BE95394-0J0gbvR4kThpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2018-12-10  8:57                                             ` joro-zLv9SwRftAIdnm+yROfE0A
     [not found]                                               ` <20181210085745.GN16835-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2018-12-11 18:34                                                 ` Jean-Philippe Brucker
     [not found]                                                   ` <4be63d12-fa1c-b180-761b-5e8ceed58545-5wv7dgnIgG8@public.gmane.org>
2018-12-12  9:22                                                     ` joro-zLv9SwRftAIdnm+yROfE0A
2018-12-12  9:31                                                 ` Tian, Kevin
     [not found]                                                   ` <AADFC41AFE54684AB9EE6CBC0274A5D19BE9D6CA-0J0gbvR4kThpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2018-12-12  9:54                                                     ` joro-zLv9SwRftAIdnm+yROfE0A
     [not found]                                                       ` <20181212095403.GU16835-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2018-12-12 10:03                                                         ` Tian, Kevin
2018-12-10  2:57                                         ` Lu Baolu
     [not found]                                           ` <bf1ee4a3-6d3f-e0db-a02a-1db819843a60-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2018-12-10  8:59                                             ` joro-zLv9SwRftAIdnm+yROfE0A
2018-12-11 13:35                                         ` Jean-Philippe Brucker
     [not found]                                           ` <fc173d9f-57e2-dd87-95d0-1c615f2e14e3-5wv7dgnIgG8@public.gmane.org>
2018-12-12  9:29                                             ` joro-zLv9SwRftAIdnm+yROfE0A
2018-11-08 18:29               ` Jean-Philippe Brucker
     [not found]                 ` <42949d93-e22c-dd4d-cd49-46efc0b73cdb-5wv7dgnIgG8@public.gmane.org>
2018-11-12 14:55                   ` joro-zLv9SwRftAIdnm+yROfE0A
     [not found]                     ` <20181112145541.GB25808-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2018-11-21 19:05                       ` Jean-Philippe Brucker
     [not found]                         ` <5dcf9238-62b2-8df6-b378-183ee09c5951-5wv7dgnIgG8@public.gmane.org>
2018-11-23 12:50                           ` joro-zLv9SwRftAIdnm+yROfE0A
2018-11-22  8:39                       ` Tian, Kevin
     [not found]                         ` <AADFC41AFE54684AB9EE6CBC0274A5D19BE5A7A7-0J0gbvR4kThpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2018-11-23 12:14                           ` joro-zLv9SwRftAIdnm+yROfE0A
2018-10-22 10:07   ` Raj, Ashok
     [not found]     ` <20181021194426.GA11201-7RUrO8UaCDyr4tA6zuQqW9h3ngVCH38I@public.gmane.org>
2018-10-22 16:03       ` Jean-Philippe Brucker
     [not found]         ` <d45c5222-68e9-1d6e-730b-bb8dbc060586-5wv7dgnIgG8@public.gmane.org>
2018-10-23 17:16           ` Raj, Ashok
     [not found]             ` <1540314963.21962.20.camel-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
2018-10-23 22:08               ` Tian, Kevin
2018-10-26  3:00           ` Lu Baolu
2018-10-22 16:48   ` Jordan Crouse
     [not found]     ` <20181022164834.GH26762-9PYrDHPZ2Orvke4nUoYGnHL1okKdlPRT@public.gmane.org>
2018-11-02  3:19       ` Lu Baolu

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