Re: [PATCH v5 5/8] iommu/arm-smmu-v3: Add bypass flag to arm_smmu_write_strtab_ent()
Robin Murphy
robin.murphy at arm.com
Mon Jun 14 03:23:07 PDT 2021
On 2021-05-24 12:02, Shameer Kolothum wrote:
> By default, disable_bypass is set and any dev without an iommu domain
> installs STE with CFG_ABORT during arm_smmu_init_bypass_stes(). Introduce
> a "bypass" flag to arm_smmu_write_strtab_ent() so that we can force it to
> install CFG_BYPASS STE for specific SIDs. This will be useful in follow
> up patch to install bypass for IORT RMR SIDs.
>
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi at huawei.com>
> ---
> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> index 754bad6092c1..f9195b740f48 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -1174,7 +1174,7 @@ static void arm_smmu_sync_ste_for_sid(struct arm_smmu_device *smmu, u32 sid)
> }
>
> static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
> - __le64 *dst)
> + __le64 *dst, bool bypass)
> {
> /*
> * This is hideously complicated, but we only really care about
> @@ -1245,7 +1245,7 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
>
> /* Bypass/fault */
> if (!smmu_domain || !(s1_cfg || s2_cfg)) {
> - if (!smmu_domain && disable_bypass)
> + if (!smmu_domain && disable_bypass && !bypass)
Umm...
> val |= FIELD_PREP(STRTAB_STE_0_CFG, STRTAB_STE_0_CFG_ABORT);
> else
> val |= FIELD_PREP(STRTAB_STE_0_CFG, STRTAB_STE_0_CFG_BYPASS);
> @@ -1320,7 +1320,7 @@ static void arm_smmu_init_bypass_stes(__le64 *strtab, unsigned int nent)
> unsigned int i;
>
> for (i = 0; i < nent; ++i) {
> - arm_smmu_write_strtab_ent(NULL, -1, strtab);
> + arm_smmu_write_strtab_ent(NULL, -1, strtab, false);
...and in particular, an operation named "init_bypass_stes" passing
bypass=false is just breaking my brain. Can we pull the logic for
default bypass/fault out to here as part of the refactoring so that it
actually makes sense?
Robin.
> strtab += STRTAB_STE_DWORDS;
> }
> }
> @@ -2097,7 +2097,7 @@ static void arm_smmu_install_ste_for_dev(struct arm_smmu_master *master)
> if (j < i)
> continue;
>
> - arm_smmu_write_strtab_ent(master, sid, step);
> + arm_smmu_write_strtab_ent(master, sid, step, false);
> }
> }
>
>
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