linux-kernel - Re: [PATCH v2 3/3] iommu: rockchip: Allocate tables from all available memory

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Message-ID: <67aab611-29cd-1a80-d0e2-e5b6523b2785@arm.com>
Date:   Thu, 15 Jun 2023 22:25:19 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     Jonas Karlman <jonas@...boo.se>, Joerg Roedel <joro@...tes.org>,
        Will Deacon <will@...nel.org>, Heiko Stuebner <heiko@...ech.de>
Cc:     Benjamin Gaignard <benjamin.gaignard@...labora.com>,
        iommu@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/3] iommu: rockchip: Allocate tables from all
 available memory

On 2023-06-15 21:10, Jonas Karlman wrote:
> Newer Rockchip SoCs, RK356x and RK3588, support more then 4GB of memory.

Older ones supposedly did too, e.g. commit 79db45be2b8b ("ARM: dts: 
rockchip: convert rk3288 device tree files to 64 bits"). Are we certain 
that nobody actually has a system with IOMMUv1 and more than 4GB of RAM?

> However, the RK IOMMU driver is using the GFP_DMA32 flag to limit
> allocation of the discovery and page tables into memory below 4GB.
> 
> Let's remove this limitation now that the discovery table address is

Nit: s/discovery/directory/g again

Thanks,
Robin.

> correctly configured for addresses above 4GB.
> 
> Signed-off-by: Jonas Karlman <jonas@...boo.se>
> ---
> v2:
> - no change
> 
>   drivers/iommu/rockchip-iommu.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
> index 62be9bf42390..46498fc382ee 100644
> --- a/drivers/iommu/rockchip-iommu.c
> +++ b/drivers/iommu/rockchip-iommu.c
> @@ -727,7 +727,7 @@ static u32 *rk_dte_get_page_table(struct rk_iommu_domain *rk_domain,
>   	if (rk_dte_is_pt_valid(dte))
>   		goto done;
>   
> -	page_table = (u32 *)get_zeroed_page(GFP_ATOMIC | GFP_DMA32);
> +	page_table = (u32 *)get_zeroed_page(GFP_ATOMIC);
>   	if (!page_table)
>   		return ERR_PTR(-ENOMEM);
>   
> @@ -1076,7 +1076,7 @@ static struct iommu_domain *rk_iommu_domain_alloc(unsigned type)
>   	 * Each level1 (dt) and level2 (pt) table has 1024 4-byte entries.
>   	 * Allocate one 4 KiB page for each table.
>   	 */
> -	rk_domain->dt = (u32 *)get_zeroed_page(GFP_KERNEL | GFP_DMA32);
> +	rk_domain->dt = (u32 *)get_zeroed_page(GFP_KERNEL);
>   	if (!rk_domain->dt)
>   		goto err_free_domain;
>