linux-kernel - Re: [PATCH v10 1/2] iommu/io-pgtable-arm-v7s: Add a quirk to allow pgtable PA up to 35bit

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Date:   Wed, 22 Jun 2022 09:28:55 +0800
From:   Yong Wu <yong.wu@...iatek.com>
To:     <yf.wang@...iatek.com>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>
CC:     <wsd_upstream@...iatek.com>, Libo Kang <Libo.Kang@...iatek.com>,
        "Miles Chen" <miles.chen@...iatek.com>,
        Ning Li <ning.li@...iatek.com>,
        "Joerg Roedel" <joro@...tes.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        "Isaac J. Manjarres" <isaacm@...eaurora.org>,
        Georgi Djakov <quic_c_gdjako@...cinc.com>,
        Sven Peter <sven@...npeter.dev>,
        "moderated list:ARM SMMU DRIVERS" 
        <linux-arm-kernel@...ts.infradead.org>,
        "open list:IOMMU DRIVERS" <iommu@...ts.linux-foundation.org>,
        open list <linux-kernel@...r.kernel.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH v10 1/2] iommu/io-pgtable-arm-v7s: Add a quirk to allow
 pgtable PA up to 35bit

On Thu, 2022-06-16 at 20:07 +0800, yf.wang@...iatek.com wrote:
> From: Yunfei Wang <yf.wang@...iatek.com>
> 
> Single memory zone feature will remove ZONE_DMA32 and ZONE_DMA and
> cause pgtable PA size larger than 32bit.
> 
> Since Mediatek IOMMU hardware support at most 35bit PA in pgtable,
> so add a quirk to allow the PA of pgtables support up to bit35.
> 
> Signed-off-by: Ning Li <ning.li@...iatek.com>
> Signed-off-by: Yunfei Wang <yf.wang@...iatek.com>
> ---
>  drivers/iommu/io-pgtable-arm-v7s.c | 67 +++++++++++++++++++++++-----
> --
>  include/linux/io-pgtable.h         | 15 ++++---
>  2 files changed, 63 insertions(+), 19 deletions(-)

[...]

>  	/* TTBR */
> -	cfg->arm_v7s_cfg.ttbr = virt_to_phys(data->pgd) |
> ARM_V7S_TTBR_S |
> +	paddr = virt_to_phys(data->pgd);
> +	cfg->arm_v7s_cfg.ttbr = paddr | ARM_V7S_TTBR_S |
>  				(cfg->coherent_walk ? (ARM_V7S_TTBR_NOS
> |
>  				 ARM_V7S_TTBR_IRGN_ATTR(ARM_V7S_RGN_WBW
> A) |
>  				 ARM_V7S_TTBR_ORGN_ATTR(ARM_V7S_RGN_WBW
> A)) :
>  				(ARM_V7S_TTBR_IRGN_ATTR(ARM_V7S_RGN_NC)
> |
>  				 ARM_V7S_TTBR_ORGN_ATTR(ARM_V7S_RGN_NC)
> ));
> +
> +	if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_TTBR_EXT)
> +		cfg->arm_v7s_cfg.ttbr = (paddr & GENMASK(31, 7)) |
> +					upper_32_bits(paddr);

If we keep ttbr u32, we have to put the special logic here. This line
is ok for all the MediaTek cases, not only for this quirk. It means:

    if (arm_v7s_is_mtk_enabled(cfg))
           cfg->arm_v7s_cfg.ttbr = (virt_to_phys(data->pgd) &
GENMASK(31, 7)) | upper_32_bits(paddr);
    else
           xxx
 
     Then we don't need add "& MMU_PT_ADDR_MASK" in mtk_iommu.c since
you have done it here.

> +
>  	return &data->iop;
>