linux-kernel - Re: [PATCH] iommu/arm-smmu-v3: Align size in __arm_smmu_tlb_inv

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Message-ID: <37c02fc4-d793-b003-f612-206c987a8a42@arm.com>
Date:   Wed, 13 Apr 2022 14:40:31 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     Nicolin Chen <nicolinc@...dia.com>, will@...nel.org,
        joro@...tes.org
Cc:     thunder.leizhen@...wei.com, jgg@...pe.ca, tglx@...utronix.de,
        john.garry@...wei.com, jean-philippe@...aro.org,
        christophe.jaillet@...adoo.fr,
        linux-arm-kernel@...ts.infradead.org,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iommu/arm-smmu-v3: Align size in __arm_smmu_tlb_inv_range

On 2022-04-13 05:17, Nicolin Chen wrote:
> To calculate num_pages, the size should be aligned with
> "page size", determined by the tg value. Otherwise, its
> following "while (iova < end)" might become an infinite
> loop if unaligned size is slightly greater than 1 << tg.

Hmm, how does a non-page-aligned invalidation request get generated in 
the first place?

Robin.

> Signed-off-by: Nicolin Chen <nicolinc@...dia.com>
> ---
>   drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> index 627a3ed5ee8f..8249dad5ae44 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -1879,7 +1879,7 @@ static void __arm_smmu_tlb_inv_range(struct arm_smmu_cmdq_ent *cmd,
>   		/* Determine what level the granule is at */
>   		cmd->tlbi.ttl = 4 - ((ilog2(granule) - 3) / (tg - 3));
>   
> -		num_pages = size >> tg;
> +		num_pages = ALIGN(size, 1 << tg) >> tg;
>   	}
>   
>   	cmds.num = 0;