Re: [v2 PATCH] iommu/arm-smmu-v3: Fix L1 stream table index calculation for 32-bit sid size

[Jason Gunthorpe]

On Wed, Oct 02, 2024 at 10:55:14AM -0700, Yang Shi wrote:

> Using 64 bit immediate when doing shift can solve the problem.  The
> disassembly after the fix looks like:
>     ldr     w20, [x19, 828] //, smmu_7(D)->sid_bits
>     mov     x0, 1
>     lsl     x0, x0, x20
> 
> There are a couple of problematic places, extracted the shift into a helper.
> 
> [1] https://lore.kernel.org/lkml/d4b53bbb-333a-45b9-9eb0-23ddd0820a14@xxxxxxx/
> Fixes: ce410410f1a7 ("iommu/arm-smmu-v3: Add arm_smmu_strtab_l1/2_idx()")
> Tested-by: James Morse <james.morse@xxxxxxx>
> Signed-off-by: Yang Shi <yang@xxxxxxxxxxxxxxxxxxxxxx>
> ---
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 8 +++++---
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 5 +++++
>  2 files changed, 10 insertions(+), 3 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>

Jason