Re: [PATCH v5 5/8] iommu/arm-smmu-v3: Add bypass flag to arm_smmu_write_strtab_ent()
From: Robin Murphy <robin.murphy@arm.com>
Date: 2021-06-14 10:24:41
Also in:
linux-arm-kernel, linux-iommu
On 2021-05-24 12:02, Shameer Kolothum wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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...
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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.
quoted hunk ↗ jump to hunk
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); } }