From: Jason Gunthorpe <jgg@nvidia.com>
To: Nicolin Chen <nicolinc@nvidia.com>
Cc: 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
Subject: Re: [PATCH rc v1 1/4] iommu/arm-smmu-v3: Add ignored bits to fix STE update sequence
Date: Sat, 6 Dec 2025 15:34:08 -0400 [thread overview]
Message-ID: <20251206193408.GD1219718@nvidia.com> (raw)
In-Reply-To: <6ec73bb7cd03d90a0764f12c4b14071158163818.1764982046.git.nicolinc@nvidia.com>
On Fri, Dec 05, 2025 at 04:52:00PM -0800, Nicolin Chen wrote:
> @@ -1106,16 +1115,17 @@ static u8 arm_smmu_entry_qword_diff(struct arm_smmu_entry_writer *writer,
> * allowed to set a bit to 1 if the used function doesn't say it
> * is used.
> */
> - WARN_ON_ONCE(target[i] & ~target_used[i]);
> + WARN_ON_ONCE(target[i] & ~target_used[i] & ~ignored[i]);
>
> /* Bits can change because they are not currently being used */
> - unused_update[i] = (entry[i] & cur_used[i]) |
> + unused_update[i] = (entry[i] & (cur_used[i] | ignored[i])) |
> (target[i] & ~cur_used[i]);
This can't be right? We don't want to ever copy an ignored bit from
entry, the ignored bits should always come from target. The line
should be left alone.
Jason
next prev parent reply other threads:[~2025-12-06 19:34 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-06 0:51 [PATCH rc v1 0/4] iommu/arm-smmu-v3: Fix hitless STE update in nesting cases Nicolin Chen
2025-12-06 0:52 ` [PATCH rc v1 1/4] iommu/arm-smmu-v3: Add ignored bits to fix STE update sequence Nicolin Chen
2025-12-06 14:19 ` Shuai Xue
2025-12-06 19:38 ` Jason Gunthorpe
2025-12-06 19:34 ` Jason Gunthorpe [this message]
2025-12-06 19:45 ` Nicolin Chen
2025-12-06 19:57 ` Jason Gunthorpe
2025-12-07 4:37 ` Nicolin Chen
2025-12-07 16:09 ` Jason Gunthorpe
2025-12-07 19:35 ` Nicolin Chen
2025-12-07 20:11 ` Nicolin Chen
2025-12-06 0:52 ` [PATCH rc v1 2/4] iommu/arm-smmu-v3: Ignore STE MEV when computing the " Nicolin Chen
2025-12-06 0:52 ` [PATCH rc v1 3/4] iommu/arm-smmu-v3: Ignore STE EATS " Nicolin Chen
2025-12-06 19:46 ` Jason Gunthorpe
2025-12-06 19:54 ` Nicolin Chen
2025-12-06 0:52 ` [PATCH rc v1 4/4] iommu/arm-smmu-v3-test: Add nested s1bypass coverage Nicolin Chen
2025-12-06 12:34 ` Shuai Xue
2025-12-06 19:42 ` Jason Gunthorpe
2025-12-06 19:50 ` Nicolin Chen
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