linux-kernel - Re: [PATCH] iommu/riscv: Fixup compile warning

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Message-ID: <CAJF2gTQomhrkYZORgG4ufRfQW3LhD4tG21GhX0v2Q=mR77mOKg@mail.gmail.com>
Date: Wed, 8 Jan 2025 14:47:54 +0800
From: Guo Ren <guoren@...nel.org>
To: Samuel Holland <samuel.holland@...ive.com>
Cc: Alexandre Ghiti <alex@...ti.fr>, tjeznach@...osinc.com, joro@...tes.org, will@...nel.org, 
	robin.murphy@....com, paul.walmsley@...ive.com, palmer@...belt.com, 
	baolu.lu@...ux.intel.com, zong.li@...ive.com, iommu@...ts.linux.dev, 
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	Guo Ren <guoren@...ux.alibaba.com>
Subject: Re: [PATCH] iommu/riscv: Fixup compile warning

Hi Samuel & Alexandre,

On Tue, Jan 7, 2025 at 1:47 AM Samuel Holland <samuel.holland@...ive.com> wrote:
>
> Hi Alex,
>
> On 2025-01-06 4:31 AM, Alexandre Ghiti wrote:
> > On 03/01/2025 03:46, guoren@...nel.org wrote:
> >> From: Guo Ren <guoren@...ux.alibaba.com>
> >>
> >> When __BITS_PER_LONG == 32, size_t is defined as unsigned int rather
> >
> >
> > RISCV_IOMMU depends on 64BIT so how do you get __BITS_PER_LONG == 32?
>
> I am guessing this is from some downstream effort to compile a 64-bit kernel
> with an ILP32 ABI. However unsupported that may be, size_t is the nominal type
> used in both riscv_iommu_pte_fetch() and above in iommu_iotlb_gather_add_page(),
> so the change does make sense.
Yes, I'm working on ILP32 ABI on CONFIG_64BIT=y. So, I got the warning
when __BITS_PER_LONG == 32.

In riscv_iommu_unmap_pages(), we've written "size_t pte_size;." So, we
should do that in "riscv_iommu_iova_to_phys()".

>
> Regards,
> Samuel
>
> >> than unsigned long. Therefore, we should use size_t to avoid
> >> type-checking errors.
> >>
> >> Fixes: 488ffbf18171 ("iommu/riscv: Paging domain support")
> >> Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
> >> Signed-off-by: Guo Ren <guoren@...nel.org>
> >> Cc: Tomasz Jeznach <tjeznach@...osinc.com>
> >> ---
> >>   drivers/iommu/riscv/iommu.c | 2 +-
> >>   1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/iommu/riscv/iommu.c b/drivers/iommu/riscv/iommu.c
> >> index 8a05def774bd..38d381164385 100644
> >> --- a/drivers/iommu/riscv/iommu.c
> >> +++ b/drivers/iommu/riscv/iommu.c
> >> @@ -1270,7 +1270,7 @@ static phys_addr_t riscv_iommu_iova_to_phys(struct
> >> iommu_domain *iommu_domain,
> >>                           dma_addr_t iova)
> >>   {
> >>       struct riscv_iommu_domain *domain = iommu_domain_to_riscv(iommu_domain);
> >> -    unsigned long pte_size;
> >> +    size_t pte_size;
> >>       unsigned long *ptr;
> >>         ptr = riscv_iommu_pte_fetch(domain, iova, &pte_size);
>


-- 
Best Regards
 Guo Ren