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

From: Andrew Jones <ajones@ventanamicro.com>
To: Tomasz Jeznach <tjeznach@rivosinc.com>
Cc: Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
	 Robin Murphy <robin.murphy@arm.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	 Anup Patel <apatel@ventanamicro.com>,
	devicetree@vger.kernel.org, Conor Dooley <conor+dt@kernel.org>,
	 Albert Ou <aou@eecs.berkeley.edu>,
	linux@rivosinc.com, linux-kernel@vger.kernel.org,
	 Rob Herring <robh+dt@kernel.org>,
	Sebastien Boeuf <seb@rivosinc.com>,
	iommu@lists.linux.dev,  Palmer Dabbelt <palmer@dabbelt.com>,
	Nick Kossifidis <mick@ics.forth.gr>,
	 Krzysztof Kozlowski <krzk+dt@kernel.org>,
	linux-riscv@lists.infradead.org
Subject: Re: [PATCH v2 7/7] iommu/riscv: Paging domain support
Date: Tue, 23 Apr 2024 19:00:39 +0200	[thread overview]
Message-ID: <20240423-64e0112d612ab1f011c4b26e@orel> (raw)
In-Reply-To: <301244bc3ff5da484b46d3fecc931cdad7d2806f.1713456598.git.tjeznach@rivosinc.com>

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