2022-11-03 22:42:42

by Chen Lin

Subject: [PATCH] iommu/arm-smmu: Warn once when the perfetcher errata patch fails to apply

Default reset value of secure banked register SMMU_sACR.cache_lock is 1.
If it is not been set to 0 by secure software(eg: atf), the non-secure
linux cannot clear ARM_MMU500_ACTLR_CPRE bit. In this situation,
the prefetcher errata is not applied successfully, warn once.

Signed-off-by: Chen Lin <[email protected]>
---
drivers/iommu/arm/arm-smmu/arm-smmu-impl.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c b/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c
index 658f3cc83278..2d2252b3e518 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c
@@ -136,6 +136,9 @@ int arm_mmu500_reset(struct arm_smmu_device *smmu)
reg = arm_smmu_cb_read(smmu, i, ARM_SMMU_CB_ACTLR);
reg &= ~ARM_MMU500_ACTLR_CPRE;
arm_smmu_cb_write(smmu, i, ARM_SMMU_CB_ACTLR, reg);
+ reg = arm_smmu_cb_read(smmu, i, ARM_SMMU_CB_ACTLR);
+ if (reg & ARM_MMU500_ACTLR_CPRE)
+ dev_warn_once(smmu->dev, "Failed to alpply prefetcher errata patch, check SMMU_sACR.cache_lock\n");
}

return 0;
--
2.25.1

2022-11-15 19:04:39

by Will Deacon

Subject: Re: [PATCH] iommu/arm-smmu: Warn once when the perfetcher errata patch fails to apply

On Fri, 4 Nov 2022 06:21:21 +0800, Chen Lin wrote:
> Default reset value of secure banked register SMMU_sACR.cache_lock is 1.
> If it is not been set to 0 by secure software(eg: atf), the non-secure
> linux cannot clear ARM_MMU500_ACTLR_CPRE bit. In this situation,
> the prefetcher errata is not applied successfully, warn once.
>
>

Applied to will (for-joerg/arm-smmu/updates), thanks!

[1/1] iommu/arm-smmu: Warn once when the perfetcher errata patch fails to apply
https://git.kernel.org/will/c/f87f6e5b4539

Cheers,
--
Will

https://fixes.arm64.dev
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