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From: Jason Gunthorpe <jgg@nvidia.com>
To: Michael Shavit <mshavit@google.com>
Cc: iommu@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, will@kernel.org,
	nicolinc@nvidia.com, tina.zhang@intel.com,
	jean-philippe@linaro.org, robin.murphy@arm.com
Subject: Re: [RFC PATCH v1 3/8] iommu/arm-smmu-v3-sva: Allocate new ASID from installed_smmus
Date: Mon, 21 Aug 2023 08:54:40 -0300	[thread overview]
Message-ID: <ZONQgNh6qarqgA+f@nvidia.com> (raw)
In-Reply-To: <CAKHBV27k8F0ZLy=RA=WhjJ7+C9JMHRRnKs=4W4pJMNmxrMEXxw@mail.gmail.com>

On Mon, Aug 21, 2023 at 05:31:23PM +0800, Michael Shavit wrote:
> On Fri, Aug 18, 2023 at 2:38 AM Jason Gunthorpe <jgg@nvidia.com> wrote:
> >
> > On Fri, Aug 18, 2023 at 02:16:25AM +0800, Michael Shavit wrote:
> > > Pick an ASID that is within the supported range of all SMMUs that the
> > > domain is installed to.
> > >
> > > Signed-off-by: Michael Shavit <mshavit@google.com>
> > > ---
> >
> > This seems like a pretty niche scenario, maybe we should just keep a
> > global for the max ASID?
> >
> > Otherwise we need a code to change the ASID, even for non-SVA domains,
> > when the domain is installed in different devices if the current ASID
> > is over the instance max..
> 
> This RFC took the other easy way out for this problem by rejecting
> attaching a domain if its currently assigned ASID/VMID
> is out of range when attaching to a new SMMU. But I'm not sure
> which of the two options is the right trade-off.
> Especially if we move VMID to a global allocator (which I plan to add
> for v2), setting a global maximum for VMID of 256 sounds small.

IMHO the simplest and best thing is to make both vmid and asid as
local allocators. Then alot of these problems disappear

Jason

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  reply	other threads:[~2023-08-21 11:55 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-17 18:16 [RFC PATCH v1 0/8] Install domain onto multiple smmus Michael Shavit
2023-08-17 18:16 ` [RFC PATCH v1 1/8] iommu/arm-smmu-v3: Add list of installed_smmus Michael Shavit
2023-08-17 19:05   ` Jason Gunthorpe
2023-08-17 19:34   ` Robin Murphy
2023-08-18  5:34     ` Michael Shavit
2023-08-17 18:16 ` [RFC PATCH v1 2/8] iommu/arm-smmu-v3: Perform invalidations over installed_smmus Michael Shavit
2023-08-17 19:20   ` Jason Gunthorpe
2023-08-17 19:41     ` Robin Murphy
2023-08-18  3:44       ` Michael Shavit
2023-08-18 13:51         ` Jason Gunthorpe
2023-08-21  8:33           ` Michael Shavit
2023-08-21 11:57             ` Jason Gunthorpe
2023-08-22  8:17               ` Michael Shavit
2023-08-22  8:21                 ` Michael Shavit
2023-08-22 10:10                 ` Michael Shavit
2023-08-22 14:15                 ` Jason Gunthorpe
2023-08-17 18:16 ` [RFC PATCH v1 3/8] iommu/arm-smmu-v3-sva: Allocate new ASID from installed_smmus Michael Shavit
2023-08-17 18:38   ` Jason Gunthorpe
2023-08-21  9:31     ` Michael Shavit
2023-08-21 11:54       ` Jason Gunthorpe [this message]
2023-08-21 13:38         ` Michael Shavit
2023-08-21 13:50           ` Jason Gunthorpe
2023-08-21 14:16             ` Michael Shavit
2023-08-21 14:26               ` Jason Gunthorpe
2023-08-21 14:39                 ` Michael Shavit
2023-08-21 14:56                   ` Jason Gunthorpe
2023-08-22  8:53                     ` Michael Shavit
2023-08-17 18:16 ` [RFC PATCH v1 4/8] iommu/arm-smmu-v3: check smmu compatibility on attach Michael Shavit
2023-08-17 19:16   ` Robin Murphy
2023-08-18  3:14     ` Michael Shavit
2023-08-17 18:16 ` [RFC PATCH v1 5/8] iommu/arm-smmu-v3: Add arm_smmu_device as a parameter to domain_finalise Michael Shavit
2023-08-17 18:16 ` [RFC PATCH v1 6/8] iommu/arm-smmu-v3: Free VMID when uninstalling domain from SMMU Michael Shavit
2023-08-17 18:50   ` Jason Gunthorpe
2023-08-17 18:16 ` [RFC PATCH v1 7/8] iommu/arm-smmu-v3: check for domain initialization using pgtbl_ops Michael Shavit
2023-08-17 18:16 ` [RFC PATCH v1 8/8] iommu/arm-smmu-v3: allow multi-SMMU domain installs Michael Shavit

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