From: Jason Gunthorpe <jgg@nvidia.com>
To: Nicolin Chen <nicolinc@nvidia.com>
Cc: Will Deacon <will@kernel.org>,
robin.murphy@arm.com, joro@8bytes.org,
linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev,
linux-kernel@vger.kernel.org, skolothumtho@nvidia.com,
praan@google.com, xueshuai@linux.alibaba.com,
smostafa@google.com
Subject: Re: [PATCH rc v5 1/4] iommu/arm-smmu-v3: Add update_safe bits to fix STE update sequence
Date: Thu, 15 Jan 2026 09:11:51 -0400 [thread overview]
Message-ID: <20260115131151.GA1081267@nvidia.com> (raw)
In-Reply-To: <20260113205112.GJ812923@nvidia.com>
On Tue, Jan 13, 2026 at 04:51:12PM -0400, Jason Gunthorpe wrote:
> > - safe_bits[1] |= cpu_to_le64(STRTAB_STE_1_EATS);
> > + if (!((cur[2] | target[2]) & cpu_to_le64(STRTAB_STE_2_S2S)))
> > + safe_bits[1] |= cpu_to_le64(
> > + FIELD_PREP(STRTAB_STE_1_EATS, STRTAB_STE_1_EATS_TRANS));
> > --------------------------------------------------------------------------
> >
> > @will, does this look good to you? I can send a v7 with this.
>
> That is an easy way to address Will's observation, makes sense to me.
Ah, but it looks like it can generate an errant view of a EATS that is
neither old or new. Ie value 3, reserved.
I think you should just check if old or new has EATS bit 1 set:
if (!((cur[2] | target[2]) & cpu_to_le64(STRTAB_STE_2_S2S)) &&
!((cur[1] | target[1]) & cpu_to_le64(FIELD_PREP(STRTAB_STE_1_EATS, 2))))
Which the current driver never does..
Jason
next prev parent reply other threads:[~2026-01-15 13:11 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-18 21:41 [PATCH rc v5 0/4] iommu/arm-smmu-v3: Fix hitless STE update in nesting cases Nicolin Chen
2025-12-18 21:41 ` [PATCH rc v5 1/4] iommu/arm-smmu-v3: Add update_safe bits to fix STE update sequence Nicolin Chen
2026-01-02 18:26 ` Mostafa Saleh
2026-01-07 21:20 ` Will Deacon
2026-01-08 0:36 ` Jason Gunthorpe
2026-01-12 15:53 ` Will Deacon
2026-01-12 16:10 ` Jason Gunthorpe
2026-01-12 18:58 ` Nicolin Chen
2026-01-13 15:05 ` Will Deacon
2026-01-13 16:12 ` Jason Gunthorpe
2026-01-13 20:29 ` Nicolin Chen
2026-01-13 20:51 ` Jason Gunthorpe
2026-01-15 13:11 ` Jason Gunthorpe [this message]
2026-01-15 16:25 ` Nicolin Chen
2026-01-15 16:29 ` Jason Gunthorpe
2026-01-15 16:34 ` Nicolin Chen
2026-01-15 17:39 ` Will Deacon
2025-12-18 21:41 ` [PATCH rc v5 2/4] iommu/arm-smmu-v3: Mark STE MEV safe when computing the " Nicolin Chen
2026-01-02 18:27 ` Mostafa Saleh
2025-12-18 21:41 ` [PATCH rc v5 3/4] iommu/arm-smmu-v3: Mark STE EATS " Nicolin Chen
2025-12-18 21:41 ` [PATCH rc v5 4/4] iommu/arm-smmu-v3-test: Add nested s1bypass/s1dssbypass coverage Nicolin Chen
2026-01-02 18:27 ` Mostafa Saleh
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