Re: [PATCH v9 2/7] iommu/arm-smmu: Add support for split pagetables

From: Rob Clark <robdclark@gmail.com>
To: Jordan Crouse <jcrouse@codeaurora.org>
Cc: linux-arm-msm <linux-arm-msm@vger.kernel.org>,
	Will Deacon <will@kernel.org>,
	Robin Murphy <robin.murphy@arm.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"list@263.net:IOMMU DRIVERS <iommu@lists.linux-foundation.org>,
	Joerg Roedel <joro@8bytes.org>,"
	<iommu@lists.linux-foundation.org>,
	John Stultz <john.stultz@linaro.org>,
	freedreno <freedreno@lists.freedesktop.org>,
	"moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v9 2/7] iommu/arm-smmu: Add support for split pagetables
Date: Thu, 2 Jul 2020 13:22:36 -0700	[thread overview]
Message-ID: <CAF6AEGuN6b5a0=Ava53vyv8E57=XCPBTZAjYrRNxtNv41VOp4Q@mail.gmail.com> (raw)
In-Reply-To: <20200626200042.13713-3-jcrouse@codeaurora.org>

On Fri, Jun 26, 2020 at 1:01 PM Jordan Crouse <jcrouse@codeaurora.org> wrote:
>
> Enable TTBR1 for a context bank if IO_PGTABLE_QUIRK_ARM_TTBR1 is selected
> by the io-pgtable configuration.
>
> Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
> ---
>
>  drivers/iommu/arm-smmu.c | 21 ++++++++++++++++-----
>  drivers/iommu/arm-smmu.h | 25 +++++++++++++++++++------
>  2 files changed, 35 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index 8a3a6c8c887a..048de2681670 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -555,11 +555,15 @@ static void arm_smmu_init_context_bank(struct arm_smmu_domain *smmu_domain,
>                         cb->ttbr[0] = pgtbl_cfg->arm_v7s_cfg.ttbr;
>                         cb->ttbr[1] = 0;
>                 } else {
> -                       cb->ttbr[0] = pgtbl_cfg->arm_lpae_s1_cfg.ttbr;
> -                       cb->ttbr[0] |= FIELD_PREP(ARM_SMMU_TTBRn_ASID,
> -                                                 cfg->asid);
> +                       cb->ttbr[0] = FIELD_PREP(ARM_SMMU_TTBRn_ASID,
> +                               cfg->asid);
>                         cb->ttbr[1] = FIELD_PREP(ARM_SMMU_TTBRn_ASID,
> -                                                cfg->asid);
> +                               cfg->asid);

above looks like stray whitespace changes?

> +
> +                       if (pgtbl_cfg->quirks & IO_PGTABLE_QUIRK_ARM_TTBR1)
> +                               cb->ttbr[1] |= pgtbl_cfg->arm_lpae_s1_cfg.ttbr;
> +                       else
> +                               cb->ttbr[0] |= pgtbl_cfg->arm_lpae_s1_cfg.ttbr;
>                 }
>         } else {
>                 cb->ttbr[0] = pgtbl_cfg->arm_lpae_s2_cfg.vttbr;
> @@ -824,7 +828,14 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain,
>
>         /* Update the domain's page sizes to reflect the page table format */
>         domain->pgsize_bitmap = pgtbl_cfg.pgsize_bitmap;
> -       domain->geometry.aperture_end = (1UL << ias) - 1;
> +
> +       if (pgtbl_cfg.quirks & IO_PGTABLE_QUIRK_ARM_TTBR1) {
> +               domain->geometry.aperture_start = ~0UL << ias;
> +               domain->geometry.aperture_end = ~0UL;
> +       } else {
> +               domain->geometry.aperture_end = (1UL << ias) - 1;
> +       }
> +
>         domain->geometry.force_aperture = true;
>
>         /* Initialise the context bank with our page table cfg */
> diff --git a/drivers/iommu/arm-smmu.h b/drivers/iommu/arm-smmu.h
> index 38b041530a4f..5f2de20e883b 100644
> --- a/drivers/iommu/arm-smmu.h
> +++ b/drivers/iommu/arm-smmu.h
> @@ -168,10 +168,12 @@ enum arm_smmu_cbar_type {
>  #define ARM_SMMU_CB_TCR                        0x30
>  #define ARM_SMMU_TCR_EAE               BIT(31)
>  #define ARM_SMMU_TCR_EPD1              BIT(23)
> +#define ARM_SMMU_TCR_A1                        BIT(22)
>  #define ARM_SMMU_TCR_TG0               GENMASK(15, 14)
>  #define ARM_SMMU_TCR_SH0               GENMASK(13, 12)
>  #define ARM_SMMU_TCR_ORGN0             GENMASK(11, 10)
>  #define ARM_SMMU_TCR_IRGN0             GENMASK(9, 8)
> +#define ARM_SMMU_TCR_EPD0              BIT(7)
>  #define ARM_SMMU_TCR_T0SZ              GENMASK(5, 0)
>
>  #define ARM_SMMU_VTCR_RES1             BIT(31)
> @@ -347,12 +349,23 @@ struct arm_smmu_domain {
>
>  static inline u32 arm_smmu_lpae_tcr(struct io_pgtable_cfg *cfg)
>  {
> -       return ARM_SMMU_TCR_EPD1 |
> -              FIELD_PREP(ARM_SMMU_TCR_TG0, cfg->arm_lpae_s1_cfg.tcr.tg) |
> -              FIELD_PREP(ARM_SMMU_TCR_SH0, cfg->arm_lpae_s1_cfg.tcr.sh) |
> -              FIELD_PREP(ARM_SMMU_TCR_ORGN0, cfg->arm_lpae_s1_cfg.tcr.orgn) |
> -              FIELD_PREP(ARM_SMMU_TCR_IRGN0, cfg->arm_lpae_s1_cfg.tcr.irgn) |
> -              FIELD_PREP(ARM_SMMU_TCR_T0SZ, cfg->arm_lpae_s1_cfg.tcr.tsz);
> +       u32 tcr = FIELD_PREP(ARM_SMMU_TCR_TG0, cfg->arm_lpae_s1_cfg.tcr.tg) |
> +               FIELD_PREP(ARM_SMMU_TCR_SH0, cfg->arm_lpae_s1_cfg.tcr.sh) |
> +               FIELD_PREP(ARM_SMMU_TCR_ORGN0, cfg->arm_lpae_s1_cfg.tcr.orgn) |
> +               FIELD_PREP(ARM_SMMU_TCR_IRGN0, cfg->arm_lpae_s1_cfg.tcr.irgn) |
> +               FIELD_PREP(ARM_SMMU_TCR_T0SZ, cfg->arm_lpae_s1_cfg.tcr.tsz);
> +
> +       /*
> +       * When TTBR1 is selected shift the TCR fields by 16 bits and disable
> +       * translation in TTBR0
> +       */
> +       if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_TTBR1) {
> +               tcr = (tcr << 16) & ~ARM_SMMU_TCR_A1;
> +               tcr |= ARM_SMMU_TCR_EPD0;
> +       } else
> +               tcr |= ARM_SMMU_TCR_EPD1;

I'm not personally a fan of if/else ladders that mix {}'s, but
Will/Robin may have a different opinion

BR,
-R

> +
> +       return tcr;
>  }
>
>  static inline u32 arm_smmu_lpae_tcr2(struct io_pgtable_cfg *cfg)
> --
> 2.17.1
>
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