From: Jason Gunthorpe <jgg@ziepe.ca>
To: Yang Shi <yang@os.amperecomputing.com>
Cc: Nicolin Chen <nicolinc@nvidia.com>,
james.morse@arm.com, will@kernel.org, robin.murphy@arm.com,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [v2 PATCH] iommu/arm-smmu-v3: Fix L1 stream table index calculation for 32-bit sid size
Date: Thu, 3 Oct 2024 08:16:03 -0300 [thread overview]
Message-ID: <20241003111603.GU1369530@ziepe.ca> (raw)
In-Reply-To: <f28cab76-8030-477a-84b1-461dc02451ff@os.amperecomputing.com>
On Wed, Oct 02, 2024 at 01:05:08PM -0700, Yang Shi wrote:
> > It would make some sense to have something like:
> >
> > u64 size = arm_smmu_strtab_max_sid()
> >
> > /* Would require too much memory */
> > if (size > SZ_512M)
> > return -EINVAL;
>
> Why not just check smmu->sid_bits?
>
> For example,
>
> if (smmu->sid_bits > 28)
> return -EINVAL;
>
> The check can happen before the shift.
Sure, but IMHO it reads a bit better to check the size computed from
the helper
MAX_PAGE_ORDER is often 10, so kmalloc will always fail before we
reach 28 bits of sid space.
Jason
next prev parent reply other threads:[~2024-10-03 11:17 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-02 17:55 [v2 PATCH] iommu/arm-smmu-v3: Fix L1 stream table index calculation for 32-bit sid size Yang Shi
2024-10-02 18:14 ` Jason Gunthorpe
2024-10-02 18:17 ` Nicolin Chen
2024-10-02 19:04 ` Yang Shi
2024-10-02 19:22 ` Nicolin Chen
2024-10-02 19:40 ` Jason Gunthorpe
2024-10-02 20:00 ` Yang Shi
2024-10-02 20:05 ` Yang Shi
2024-10-03 11:16 ` Jason Gunthorpe [this message]
2024-10-03 15:31 ` Yang Shi
2024-10-04 12:43 ` Jason Gunthorpe
2024-10-04 16:05 ` Yang Shi
2024-10-04 16:14 ` Jason Gunthorpe
2024-10-04 16:29 ` Yang Shi
2024-10-04 16:37 ` Yang Shi
2024-10-04 16:41 ` Jason Gunthorpe
2024-10-04 16:46 ` Yang Shi
2024-10-02 19:50 ` Yang Shi
2024-10-02 18:21 ` Robin Murphy
2024-10-02 18:36 ` Yang Shi
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