From: Jason Gunthorpe <jgg@ziepe.ca>
To: Ryan Roberts <ryan.roberts@arm.com>
Cc: "Mikołaj Lenczewski" <miko.lenczewski@arm.com>,
"Shameerali Kolothum Thodi"
<shameerali.kolothum.thodi@huawei.com>,
"suzuki.poulose@arm.com" <suzuki.poulose@arm.com>,
"yang@os.amperecomputing.com" <yang@os.amperecomputing.com>,
"catalin.marinas@arm.com" <catalin.marinas@arm.com>,
"will@kernel.org" <will@kernel.org>,
"joro@8bytes.org" <joro@8bytes.org>,
"jean-philippe@linaro.org" <jean-philippe@linaro.org>,
"mark.rutland@arm.com" <mark.rutland@arm.com>,
"joey.gouly@arm.com" <joey.gouly@arm.com>,
"oliver.upton@linux.dev" <oliver.upton@linux.dev>,
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"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"iommu@lists.linux.dev" <iommu@lists.linux.dev>
Subject: Re: [PATCH v2 4/4] iommu/arm: Add BBM Level 2 smmu feature
Date: Tue, 4 Mar 2025 12:19:43 -0400 [thread overview]
Message-ID: <20250304161943.GD5011@ziepe.ca> (raw)
In-Reply-To: <67fbe3f4-4fb6-4753-b34c-320b7897fd16@arm.com>
On Tue, Mar 04, 2025 at 04:02:20PM +0000, Ryan Roberts wrote:
> On 04/03/2025 14:26, Jason Gunthorpe wrote:
> > On Mon, Mar 03, 2025 at 07:03:42PM +0000, Mikołaj Lenczewski wrote:
> >
> >> For example, if we use BBML2 for kernel mappings, does that require us
> >> to repaint all kernel mappings when disabling BBML2 on smmu attach? I
> >> am not sure, but definitely something to be worked out.
> >
> > No, it would be a per-mm_struct basis only if we did something like
> > that
> >
> > When the SMMU driver puts a SVA on top of the mm_struct it would
> > disable BBML2 usage only for that mm_struct and it's contained VMAs.
>
> I guess we would need to figure out some synchonization mechanism if disabling
> BBML2 dynaically per-mm. If there was already a BBML2 operation in flight would
> want to wait for it to end. But that's a problem to solve if/when it's shown to
> be needed, I think.
I have a feeling we can piggyback on the mmu notifiers to achieve this
as all the changes to the PTEs should be bracketed by notifier
callbacks..
Let's hope it isn't needed.
Jasob
next prev parent reply other threads:[~2025-03-04 16:19 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-28 18:24 [PATCH v2 0/4] Initial BBML2 support for contpte_convert() Mikołaj Lenczewski
2025-02-28 18:24 ` [PATCH v2 1/4] arm64: Add BBM Level 2 cpu feature Mikołaj Lenczewski
2025-02-28 21:16 ` Yang Shi
2025-03-01 1:29 ` Yang Shi
2025-03-01 2:45 ` Yang Shi
2025-03-03 9:40 ` Mikołaj Lenczewski
2025-03-03 9:40 ` Mikołaj Lenczewski
2025-03-03 19:55 ` Yang Shi
2025-02-28 18:24 ` [PATCH v2 2/4] arm64/mm: Delay tlbi in contpte_convert() under BBML2 Mikołaj Lenczewski
2025-02-28 18:24 ` [PATCH v2 3/4] arm64/mm: Elide " Mikołaj Lenczewski
2025-03-03 9:17 ` David Hildenbrand
2025-03-03 9:49 ` Mikołaj Lenczewski
2025-03-03 9:57 ` David Hildenbrand
2025-03-03 10:55 ` Mikołaj Lenczewski
2025-03-03 11:42 ` David Hildenbrand
2025-03-03 11:52 ` Mikołaj Lenczewski
2025-02-28 18:24 ` [PATCH v2 4/4] iommu/arm: Add BBM Level 2 smmu feature Mikołaj Lenczewski
2025-02-28 19:32 ` Jason Gunthorpe
2025-03-03 8:49 ` Shameerali Kolothum Thodi
2025-03-03 10:31 ` Mikołaj Lenczewski
2025-03-03 16:52 ` Jason Gunthorpe
2025-03-03 19:03 ` Mikołaj Lenczewski
2025-03-04 14:26 ` Jason Gunthorpe
2025-03-04 16:02 ` Ryan Roberts
2025-03-04 16:19 ` Jason Gunthorpe [this message]
2025-03-11 14:37 ` Robin Murphy
2025-03-01 1:32 ` Yang Shi
2025-03-03 10:17 ` Ryan Roberts
2025-03-03 10:32 ` Mikołaj Lenczewski
2025-03-03 19:56 ` Yang Shi
2025-03-11 10:17 ` Suzuki K Poulose
2025-03-11 10:58 ` Ryan Roberts
2025-03-11 12:16 ` Suzuki K Poulose
2025-03-11 13:20 ` Ryan Roberts
2025-03-03 9:14 ` [PATCH v2 0/4] Initial BBML2 support for contpte_convert() David Hildenbrand
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