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Date: Wed, 18 Mar 2020 22:34:00 +0000
From: Will Deacon <will@...nel.org>
To: Jordan Crouse <jcrouse@...eaurora.org>
Cc: iommu@...ts.linux-foundation.org, robin.murphy@....com,
linux-arm-kernel@...ts.infradead.org,
linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
Joerg Roedel <joro@...tes.org>
Subject: Re: [PATCH v5 2/5] iommu/arm-smmu: Add support for TTBR1
On Tue, Jan 28, 2020 at 03:00:16PM -0700, Jordan Crouse wrote:
> Add support to enable TTBR1 if the domain requests it via the
> DOMAIN_ATTR_SPLIT_TABLES attribute. If enabled by the hardware
> and pagetable configuration the driver will configure the TTBR1 region
> and program the domain pagetable on TTBR1. TTBR0 will be disabled.
>
> After attaching the device the value of he domain attribute can
> be queried to see if the split pagetables were successfully programmed.
> The domain geometry will be updated as well so that the caller can
> determine the active region for the pagetable that was programmed.
>
> Signed-off-by: Jordan Crouse <jcrouse@...eaurora.org>
> ---
>
> drivers/iommu/arm-smmu.c | 48 +++++++++++++++++++++++++++++++++++++++++-------
> drivers/iommu/arm-smmu.h | 22 ++++++++++++++++------
> 2 files changed, 57 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index 16c4b87..23b22fa 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -557,11 +557,17 @@ 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[1] = FIELD_PREP(ARM_SMMU_TTBRn_ASID,
> - cfg->asid);
I think it would be clearer if you set the ASID in TTBR0 unconditionally
here...
> + if (pgtbl_cfg->quirks & IO_PGTABLE_QUIRK_ARM_TTBR1) {
> + cb->ttbr[0] = FIELD_PREP(ARM_SMMU_TTBRn_ASID,
> + cfg->asid);
> + cb->ttbr[1] = pgtbl_cfg->arm_lpae_s1_cfg.ttbr;
> + } else {
> + cb->ttbr[0] = pgtbl_cfg->arm_lpae_s1_cfg.ttbr;
> + cb->ttbr[0] |= FIELD_PREP(ARM_SMMU_TTBRn_ASID,
> + cfg->asid);
... and then OR'd in the TTBR base here.
> + cb->ttbr[1] = FIELD_PREP(ARM_SMMU_TTBRn_ASID,
> + cfg->asid);
> + }
> }
> } else {
> cb->ttbr[0] = pgtbl_cfg->arm_lpae_s2_cfg.vttbr;
> @@ -675,6 +681,7 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain,
> enum io_pgtable_fmt fmt;
> struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
> struct arm_smmu_cfg *cfg = &smmu_domain->cfg;
> + unsigned long quirks = 0;
>
> mutex_lock(&smmu_domain->init_mutex);
> if (smmu_domain->smmu)
> @@ -743,6 +750,14 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain,
> oas = smmu->ipa_size;
> if (cfg->fmt == ARM_SMMU_CTX_FMT_AARCH64) {
> fmt = ARM_64_LPAE_S1;
> +
> + /*
> + * We are assuming that split pagetables will always use
> + * SEP_UPSTREAM so we don't need to reduce the size of
> + * the ias to account for the sign extension bit
> + */
> + if (smmu_domain->split_pagetables)
> + quirks |= IO_PGTABLE_QUIRK_ARM_TTBR1;
> } else if (cfg->fmt == ARM_SMMU_CTX_FMT_AARCH32_L) {
> fmt = ARM_32_LPAE_S1;
> ias = min(ias, 32UL);
> @@ -812,6 +827,7 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain,
> .coherent_walk = smmu->features & ARM_SMMU_FEAT_COHERENT_WALK,
> .tlb = smmu_domain->flush_ops,
> .iommu_dev = smmu->dev,
> + .quirks = quirks,
> };
>
> if (smmu_domain->non_strict)
> @@ -825,8 +841,15 @@ 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;
> - domain->geometry.force_aperture = true;
> +
> + 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;
> + smmu_domain->split_pagetables = false;
> + }
Why do you only force the aperture for TTBR0?
> diff --git a/drivers/iommu/arm-smmu.h b/drivers/iommu/arm-smmu.h
> index 8d1cd54..53053fd 100644
> --- a/drivers/iommu/arm-smmu.h
> +++ b/drivers/iommu/arm-smmu.h
> @@ -172,6 +172,7 @@ enum arm_smmu_cbar_type {
> #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)
> @@ -343,16 +344,25 @@ struct arm_smmu_domain {
> struct mutex init_mutex; /* Protects smmu pointer */
> spinlock_t cb_lock; /* Serialises ATS1* ops and TLB syncs */
> struct iommu_domain domain;
> + bool split_pagetables;
> };
>
> 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)
> + return (tcr << 16) | ARM_SMMU_TCR_EPD0;
> +
> + return tcr | ARM_SMMU_TCR_EPD1;
> }
Please give this a single return statement, i.e.
if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_TTBR1)
tcr = (tcr << 16) | ARM_SMMU_TCR_EPD0;
else
tcr |= ARM_SMMU_TCR_EPD1;
return tcr;
Will
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