linux-kernel - Re: [PATCH v2 7/7] iommu/riscv: Paging domain support

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Message-ID: <20240423-64e0112d612ab1f011c4b26e@orel>
Date: Tue, 23 Apr 2024 19:00:39 +0200
From: Andrew Jones <ajones@...tanamicro.com>
To: Tomasz Jeznach <tjeznach@...osinc.com>
Cc: Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>, 
	Robin Murphy <robin.murphy@....com>, Paul Walmsley <paul.walmsley@...ive.com>, 
	Anup Patel <apatel@...tanamicro.com>, devicetree@...r.kernel.org, Conor Dooley <conor+dt@...nel.org>, 
	Albert Ou <aou@...s.berkeley.edu>, linux@...osinc.com, linux-kernel@...r.kernel.org, 
	Rob Herring <robh+dt@...nel.org>, Sebastien Boeuf <seb@...osinc.com>, iommu@...ts.linux.dev, 
	Palmer Dabbelt <palmer@...belt.com>, Nick Kossifidis <mick@....forth.gr>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, linux-riscv@...ts.infradead.org
Subject: Re: [PATCH v2 7/7] iommu/riscv: Paging domain support

On Thu, Apr 18, 2024 at 09:32:25AM -0700, Tomasz Jeznach wrote:
..
> +static size_t riscv_iommu_unmap_pages(struct iommu_domain *iommu_domain,
> +				      unsigned long iova, size_t pgsize, size_t pgcount,
> +				      struct iommu_iotlb_gather *gather)
> +{
> +	struct riscv_iommu_domain *domain = iommu_domain_to_riscv(iommu_domain);
> +	size_t size = pgcount << __ffs(pgsize);
> +	unsigned long *ptr, old;
> +	size_t unmapped = 0;
> +	size_t pte_size;
> +
> +	while (unmapped < size) {
> +		ptr = riscv_iommu_pte_fetch(domain, iova, &pte_size);
> +		if (!ptr)
> +			return unmapped;
> +
> +		/* partial unmap is not allowed, fail. */
> +		if (iova & ~(pte_size - 1))
                           ^ Shouldn't this ~ be removed?

> +			return unmapped;
> +
> +		old = READ_ONCE(*ptr);
> +		if (cmpxchg_relaxed(ptr, old, 0) != old)
> +			continue;
> +
> +		iommu_iotlb_gather_add_page(&domain->domain, gather, iova,
> +					    pte_size);
> +
> +		iova += pte_size;
> +		unmapped += pte_size;
> +	}
> +
> +	return unmapped;
> +}
> +

Thanks,
drew