On Thu, Apr 09, 2020 at 05:33:47PM -0600, 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 <jcro...@codeaurora.org>
> ---
>
> drivers/iommu/arm-smmu.c | 48 ++++++++++++++++++++++++++++++++++------
> drivers/iommu/arm-smmu.h | 24 +++++++++++++++-----
> 2 files changed, 59 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index a6a5796e9c41..db6d503c1673 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -555,11 +555,16 @@ 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);
> + cb->ttbr[0] = FIELD_PREP(ARM_SMMU_TTBRn_ASID,
> + cfg->asid);
> +
> + 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;
> + cb->ttbr[1] = FIELD_PREP(ARM_SMMU_TTBRn_ASID,
> + cfg->asid);
> + }
This looks odd to me. As I mentioned before, the SMMU driver absolutely has
to manage the ASID space, so we should be setting it in both TTBRs here.
> diff --git a/drivers/iommu/arm-smmu.h b/drivers/iommu/arm-smmu.h
> index 8d1cd54d82a6..5f6d0af7c8c8 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 +344,27 @@ 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)
> + tcr = (tcr << 16) | ARM_SMMU_TCR_EPD0;
This looks reasonably dodgy to me, as you copy a RESERVED bit into the A1
field. Furthermore, for 32-bit context banks you've got the EAE bit to
contend with as well.
Perhaps we shouldn't expose DOMAIN_ATTR_SPLIT_TABLES for anything other than
the 64-bit page table format.
Will
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