linux-kernel - Re: [PATCH] iommu/sun50i: Allow page sizes between 4K and 1M

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Message-ID: <40649946-739b-fec6-d743-f7828613fec5@arm.com>
Date:   Mon, 11 Sep 2023 20:06:12 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     Jernej Skrabec <jernej.skrabec@...il.com>, joro@...tes.org,
        will@...nel.org
Cc:     wens@...e.org, samuel@...lland.org, iommu@...ts.linux.dev,
        linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iommu/sun50i: Allow page sizes between 4K and 1M

On 2023-09-11 20:02, Jernej Skrabec wrote:
> While peripheral supports only 4K page sizes, we can easily emulate
> support for bigger page sizes, up to 1M. This is done by making multiple
> entries in map function or clearing multiple entries in unmap.

No, it's done by converting over to the {map,unmap}_pages ops. There's 
no need to resurrect this horrible bodge.

Thanks,
Robin.

> Signed-off-by: Jernej Skrabec <jernej.skrabec@...il.com>
> ---
>   drivers/iommu/sun50i-iommu.c | 49 +++++++++++++++++++++++-------------
>   1 file changed, 31 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/iommu/sun50i-iommu.c b/drivers/iommu/sun50i-iommu.c
> index 74c5cb93e900..93077575d60f 100644
> --- a/drivers/iommu/sun50i-iommu.c
> +++ b/drivers/iommu/sun50i-iommu.c
> @@ -95,6 +95,10 @@
>   
>   #define SPAGE_SIZE			4096
>   
> +#define SUN50I_IOMMU_PGSIZES		(SZ_4K | SZ_8K | SZ_16K | SZ_32K | \
> +					 SZ_64K | SZ_128K | SZ_256K | \
> +					 SZ_512K | SZ_1M)
> +
>   struct sun50i_iommu {
>   	struct iommu_device iommu;
>   
> @@ -593,10 +597,12 @@ static int sun50i_iommu_map(struct iommu_domain *domain, unsigned long iova,
>   {
>   	struct sun50i_iommu_domain *sun50i_domain = to_sun50i_domain(domain);
>   	struct sun50i_iommu *iommu = sun50i_domain->iommu;
> -	u32 pte_index;
> +	u32 pte_index, pages, i;
>   	u32 *page_table, *pte_addr;
>   	int ret = 0;
>   
> +	pages = size / SPAGE_SIZE;
> +
>   	page_table = sun50i_dte_get_page_table(sun50i_domain, iova, gfp);
>   	if (IS_ERR(page_table)) {
>   		ret = PTR_ERR(page_table);
> @@ -604,18 +610,22 @@ static int sun50i_iommu_map(struct iommu_domain *domain, unsigned long iova,
>   	}
>   
>   	pte_index = sun50i_iova_get_pte_index(iova);
> -	pte_addr = &page_table[pte_index];
> -	if (unlikely(sun50i_pte_is_page_valid(*pte_addr))) {
> -		phys_addr_t page_phys = sun50i_pte_get_page_address(*pte_addr);
> -		dev_err(iommu->dev,
> -			"iova %pad already mapped to %pa cannot remap to %pa prot: %#x\n",
> -			&iova, &page_phys, &paddr, prot);
> -		ret = -EBUSY;
> -		goto out;
> +	for (i = 0; i < pages; i++) {
> +		pte_addr = &page_table[pte_index + i];
> +		if (unlikely(sun50i_pte_is_page_valid(*pte_addr))) {
> +			phys_addr_t page_phys = sun50i_pte_get_page_address(*pte_addr);
> +
> +			dev_err(iommu->dev,
> +				"iova %pad already mapped to %pa cannot remap to %pa prot: %#x\n",
> +				&iova, &page_phys, &paddr, prot);
> +			ret = -EBUSY;
> +			goto out;
> +		}
> +		*pte_addr = sun50i_mk_pte(paddr, prot);
> +		paddr += SPAGE_SIZE;
>   	}
>   
> -	*pte_addr = sun50i_mk_pte(paddr, prot);
> -	sun50i_table_flush(sun50i_domain, pte_addr, 1);
> +	sun50i_table_flush(sun50i_domain, &page_table[pte_index], pages);
>   
>   out:
>   	return ret;
> @@ -626,8 +636,10 @@ static size_t sun50i_iommu_unmap(struct iommu_domain *domain, unsigned long iova
>   {
>   	struct sun50i_iommu_domain *sun50i_domain = to_sun50i_domain(domain);
>   	phys_addr_t pt_phys;
> +	u32 dte, pages, i;
>   	u32 *pte_addr;
> -	u32 dte;
> +
> +	pages = size / SPAGE_SIZE;
>   
>   	dte = sun50i_domain->dt[sun50i_iova_get_dte_index(iova)];
>   	if (!sun50i_dte_is_pt_valid(dte))
> @@ -636,13 +648,14 @@ static size_t sun50i_iommu_unmap(struct iommu_domain *domain, unsigned long iova
>   	pt_phys = sun50i_dte_get_pt_address(dte);
>   	pte_addr = (u32 *)phys_to_virt(pt_phys) + sun50i_iova_get_pte_index(iova);
>   
> -	if (!sun50i_pte_is_page_valid(*pte_addr))
> -		return 0;
> +	for (i = 0; i < pages; i++)
> +		if (!sun50i_pte_is_page_valid(pte_addr[i]))
> +			return 0;
>   
> -	memset(pte_addr, 0, sizeof(*pte_addr));
> -	sun50i_table_flush(sun50i_domain, pte_addr, 1);
> +	memset(pte_addr, 0, sizeof(*pte_addr) * pages);
> +	sun50i_table_flush(sun50i_domain, pte_addr, pages);
>   
> -	return SZ_4K;
> +	return size;
>   }
>   
>   static phys_addr_t sun50i_iommu_iova_to_phys(struct iommu_domain *domain,
> @@ -827,7 +840,7 @@ static int sun50i_iommu_of_xlate(struct device *dev,
>   }
>   
>   static const struct iommu_ops sun50i_iommu_ops = {
> -	.pgsize_bitmap	= SZ_4K,
> +	.pgsize_bitmap	= SUN50I_IOMMU_PGSIZES,
>   	.device_group	= sun50i_iommu_device_group,
>   	.domain_alloc	= sun50i_iommu_domain_alloc,
>   	.of_xlate	= sun50i_iommu_of_xlate,