[PATCH v7 7/9] iommu/arm-smmu-v3: Move the CD generation for SVA into a function

Jason Gunthorpe
2024-04-16T19:29:57Z

Pull all the calculations for building the CD table entry for a mmu_struct
into arm_smmu_make_sva_cd().

Call it in the two places installing the SVA CD table entry.

Open code the last caller of arm_smmu_update_ctx_desc_devices() and remove
the function.

Remove arm_smmu_write_ctx_desc() since all callers are gone. Add the
locking assertions to arm_smmu_alloc_cd_ptr() since
arm_smmu_update_ctx_desc_devices() was the last problematic caller.

Remove quiet_cd since all users are gone, arm_smmu_make_sva_cd() creates
the same value.

The behavior of quiet_cd changes slightly, the old implementation edited
the CD in place to set CTXDESC_CD_0_TCR_EPD0 assuming it was a SVA CD
entry. This version generates a full CD entry with a 0 TTB0 and relies on
arm_smmu_write_cd_entry() to install it hitlessly.

Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
.../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c | 156 +++++++++++-------
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 103 +-----------
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 7 +-
3 files changed, 108 insertions(+), 158 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
index 7cf286f7a009fb..80a7d559ef2d3f 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
@@ -34,25 +34,6 @@ struct arm_smmu_bond {

static DEFINE_MUTEX(sva_lock);

-/*
- * Write the CD to the CD tables for all masters that this domain is attached
- * to. Note that this is only used to update existing CD entries in the target
- * CD table, for which it's assumed that arm_smmu_write_ctx_desc can't fail.
- */
-static void arm_smmu_update_ctx_desc_devices(struct arm_smmu_domain *smmu_domain,
- int ssid,
- struct arm_smmu_ctx_desc *cd)
-{
- struct arm_smmu_master *master;
- unsigned long flags;
-
- spin_lock_irqsave(&smmu_domain->devices_lock, flags);
- list_for_each_entry(master, &smmu_domain->devices, domain_head) {
- arm_smmu_write_ctx_desc(master, ssid, cd);
- }
- spin_unlock_irqrestore(&smmu_domain->devices_lock, flags);
-}
-
static void
arm_smmu_update_s1_domain_cd_entry(struct arm_smmu_domain *smmu_domain)
{
@@ -128,11 +109,86 @@ arm_smmu_share_asid(struct mm_struct *mm, u16 asid)
return NULL;
}

+static u64 page_size_to_cd(void)
+{
+ static_assert(PAGE_SIZE == SZ_4K || PAGE_SIZE == SZ_16K ||
+ PAGE_SIZE == SZ_64K);
+ if (PAGE_SIZE == SZ_64K)
+ return ARM_LPAE_TCR_TG0_64K;
+ if (PAGE_SIZE == SZ_16K)
+ return ARM_LPAE_TCR_TG0_16K;
+ return ARM_LPAE_TCR_TG0_4K;
+}
+
+static void arm_smmu_make_sva_cd(struct arm_smmu_cd *target,
+ struct arm_smmu_master *master,
+ struct mm_struct *mm, u16 asid)
+{
+ u64 par;
+
+ memset(target, 0, sizeof(*target));
+
+ par = cpuid_feature_extract_unsigned_field(
+ read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1),
+ ID_AA64MMFR0_EL1_PARANGE_SHIFT);
+
+ target->data[0] = cpu_to_le64(
+ CTXDESC_CD_0_TCR_EPD1 |
+#ifdef __BIG_ENDIAN
+ CTXDESC_CD_0_ENDI |
+#endif
+ CTXDESC_CD_0_V |
+ FIELD_PREP(CTXDESC_CD_0_TCR_IPS, par) |
+ CTXDESC_CD_0_AA64 |
+ (master->stall_enabled ? CTXDESC_CD_0_S : 0) |
+ CTXDESC_CD_0_R |
+ CTXDESC_CD_0_A |
+ CTXDESC_CD_0_ASET |
+ FIELD_PREP(CTXDESC_CD_0_ASID, asid));
+
+ /*
+ * If no MM is passed then this creates a SVA entry that faults
+ * everything. arm_smmu_write_cd_entry() can hitlessly go between these
+ * two entries types since TTB0 is ignored by HW when EPD0 is set.
+ */
+ if (mm) {
+ target->data[0] |= cpu_to_le64(
+ FIELD_PREP(CTXDESC_CD_0_TCR_T0SZ,
+ 64ULL - vabits_actual) |
+ FIELD_PREP(CTXDESC_CD_0_TCR_TG0, page_size_to_cd()) |
+ FIELD_PREP(CTXDESC_CD_0_TCR_IRGN0,
+ ARM_LPAE_TCR_RGN_WBWA) |
+ FIELD_PREP(CTXDESC_CD_0_TCR_ORGN0,
+ ARM_LPAE_TCR_RGN_WBWA) |
+ FIELD_PREP(CTXDESC_CD_0_TCR_SH0, ARM_LPAE_TCR_SH_IS));
+
+ target->data[1] = cpu_to_le64(virt_to_phys(mm->pgd) &
+ CTXDESC_CD_1_TTB0_MASK);
+ } else {
+ target->data[0] |= cpu_to_le64(CTXDESC_CD_0_TCR_EPD0);
+
+ /*
+ * Disable stall and immediately generate an abort if stall
+ * disable is permitted. This speeds up cleanup for an unclean
+ * exit if the device is still doing a lot of DMA.
+ */
+ if (master->stall_enabled &&
+ !(master->smmu->features & ARM_SMMU_FEAT_STALL_FORCE))
+ target->data[0] &=
+ cpu_to_le64(~(CTXDESC_CD_0_S | CTXDESC_CD_0_R));
+ }
+
+ /*
+ * MAIR value is pretty much constant and global, so we can just get it
+ * from the current CPU register
+ */
+ target->data[3] = cpu_to_le64(read_sysreg(mair_el1));
+}
+
static struct arm_smmu_ctx_desc *arm_smmu_alloc_shared_cd(struct mm_struct *mm)
{
u16 asid;
int err = 0;
- u64 tcr, par, reg;
struct arm_smmu_ctx_desc *cd;
struct arm_smmu_ctx_desc *ret = NULL;

@@ -166,39 +222,6 @@ static struct arm_smmu_ctx_desc *arm_smmu_alloc_shared_cd(struct mm_struct *mm)
if (err)
goto out_free_asid;

- tcr = FIELD_PREP(CTXDESC_CD_0_TCR_T0SZ, 64ULL - vabits_actual) |
- FIELD_PREP(CTXDESC_CD_0_TCR_IRGN0, ARM_LPAE_TCR_RGN_WBWA) |
- FIELD_PREP(CTXDESC_CD_0_TCR_ORGN0, ARM_LPAE_TCR_RGN_WBWA) |
- FIELD_PREP(CTXDESC_CD_0_TCR_SH0, ARM_LPAE_TCR_SH_IS) |
- CTXDESC_CD_0_TCR_EPD1 | CTXDESC_CD_0_AA64;
-
- switch (PAGE_SIZE) {
- case SZ_4K:
- tcr |= FIELD_PREP(CTXDESC_CD_0_TCR_TG0, ARM_LPAE_TCR_TG0_4K);
- break;
- case SZ_16K:
- tcr |= FIELD_PREP(CTXDESC_CD_0_TCR_TG0, ARM_LPAE_TCR_TG0_16K);
- break;
- case SZ_64K:
- tcr |= FIELD_PREP(CTXDESC_CD_0_TCR_TG0, ARM_LPAE_TCR_TG0_64K);
- break;
- default:
- WARN_ON(1);
- err = -EINVAL;
- goto out_free_asid;
- }
-
- reg = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1);
- par = cpuid_feature_extract_unsigned_field(reg, ID_AA64MMFR0_EL1_PARANGE_SHIFT);
- tcr |= FIELD_PREP(CTXDESC_CD_0_TCR_IPS, par);
-
- cd->ttbr = virt_to_phys(mm->pgd);
- cd->tcr = tcr;
- /*
- * MAIR value is pretty much constant and global, so we can just get it
- * from the current CPU register
- */
- cd->mair = read_sysreg(mair_el1);
cd->asid = asid;
cd->mm = mm;

@@ -276,6 +299,8 @@ static void arm_smmu_mm_release(struct mmu_notifier *mn, struct mm_struct *mm)
{
struct arm_smmu_mmu_notifier *smmu_mn = mn_to_smmu(mn);
struct arm_smmu_domain *smmu_domain = smmu_mn->domain;
+ struct arm_smmu_master *master;
+ unsigned long flags;

mutex_lock(&sva_lock);
if (smmu_mn->cleared) {
@@ -287,8 +312,19 @@ static void arm_smmu_mm_release(struct mmu_notifier *mn, struct mm_struct *mm)
* DMA may still be running. Keep the cd valid to avoid C_BAD_CD events,
* but disable translation.
*/
- arm_smmu_update_ctx_desc_devices(smmu_domain, mm_get_enqcmd_pasid(mm),
- &quiet_cd);
+ spin_lock_irqsave(&smmu_domain->devices_lock, flags);
+ list_for_each_entry(master, &smmu_domain->devices, domain_head) {
+ struct arm_smmu_cd target;
+ struct arm_smmu_cd *cdptr;
+
+ cdptr = arm_smmu_get_cd_ptr(master, mm_get_enqcmd_pasid(mm));
+ if (WARN_ON(!cdptr))
+ continue;
+ arm_smmu_make_sva_cd(&target, master, NULL, smmu_mn->cd->asid);
+ arm_smmu_write_cd_entry(master, mm_get_enqcmd_pasid(mm), cdptr,
+ &target);
+ }
+ spin_unlock_irqrestore(&smmu_domain->devices_lock, flags);

arm_smmu_tlb_inv_asid(smmu_domain->smmu, smmu_mn->cd->asid);
arm_smmu_atc_inv_domain(smmu_domain, mm_get_enqcmd_pasid(mm), 0, 0);
@@ -383,6 +419,8 @@ static int __arm_smmu_sva_bind(struct device *dev, ioasid_t pasid,
struct mm_struct *mm)
{
int ret;
+ struct arm_smmu_cd target;
+ struct arm_smmu_cd *cdptr;
struct arm_smmu_bond *bond;
struct arm_smmu_master *master = dev_iommu_priv_get(dev);
struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
@@ -409,9 +447,13 @@ static int __arm_smmu_sva_bind(struct device *dev, ioasid_t pasid,
goto err_free_bond;
}

- ret = arm_smmu_write_ctx_desc(master, pasid, bond->smmu_mn->cd);
- if (ret)
+ cdptr = arm_smmu_alloc_cd_ptr(master, mm_get_enqcmd_pasid(mm));
+ if (!cdptr) {
+ ret = -ENOMEM;
goto err_put_notifier;
+ }
+ arm_smmu_make_sva_cd(&target, master, mm, bond->smmu_mn->cd->asid);
+ arm_smmu_write_cd_entry(master, pasid, cdptr, &target);

list_add(&bond->list, &master->bonds);
return 0;
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 0aacd95f34a479..d01b632197c0b7 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -84,12 +84,6 @@ struct arm_smmu_option_prop {
DEFINE_XARRAY_ALLOC1(arm_smmu_asid_xa);
DEFINE_MUTEX(arm_smmu_asid_lock);

-/*
- * Special value used by SVA when a process dies, to quiesce a CD without
- * disabling it.
- */
-struct arm_smmu_ctx_desc quiet_cd = { 0 };
-
static struct arm_smmu_option_prop arm_smmu_options[] = {
{ ARM_SMMU_OPT_SKIP_PREFETCH, "hisilicon,broken-prefetch-cmd" },
{ ARM_SMMU_OPT_PAGE0_REGS_ONLY, "cavium,cn9900-broken-page1-regspace"},
@@ -1201,7 +1195,7 @@ static void arm_smmu_write_cd_l1_desc(__le64 *dst,
u64 val = (l1_desc->l2ptr_dma & CTXDESC_L1_DESC_L2PTR_MASK) |
CTXDESC_L1_DESC_V;

- /* See comment in arm_smmu_write_ctx_desc() */
+ /* The HW has 64 bit atomicity with stores to the L2 CD table */
WRITE_ONCE(*dst, cpu_to_le64(val));
}

@@ -1224,12 +1218,15 @@ struct arm_smmu_cd *arm_smmu_get_cd_ptr(struct arm_smmu_master *master,
return &l1_desc->l2ptr[ssid % CTXDESC_L2_ENTRIES];
}

-static struct arm_smmu_cd *arm_smmu_alloc_cd_ptr(struct arm_smmu_master *master,
- u32 ssid)
+struct arm_smmu_cd *arm_smmu_alloc_cd_ptr(struct arm_smmu_master *master,
+ u32 ssid)
{
struct arm_smmu_ctx_desc_cfg *cd_table = &master->cd_table;
struct arm_smmu_device *smmu = master->smmu;

+ might_sleep();
+ iommu_group_mutex_assert(master->dev);
+
if (!cd_table->cdtab) {
if (arm_smmu_alloc_cd_tables(master))
return NULL;
@@ -1345,91 +1342,6 @@ void arm_smmu_clear_cd(struct arm_smmu_master *master, ioasid_t ssid)
arm_smmu_write_cd_entry(master, ssid, cdptr, &target);
}

-static void arm_smmu_clean_cd_entry(struct arm_smmu_cd *target)
-{
- struct arm_smmu_cd used = {};
- int i;
-
- arm_smmu_get_cd_used(target->data, used.data);
- for (i = 0; i != ARRAY_SIZE(target->data); i++)
- target->data[i] &= used.data[i];
-}
-
-int arm_smmu_write_ctx_desc(struct arm_smmu_master *master, int ssid,
- struct arm_smmu_ctx_desc *cd)
-{
- /*
- * This function handles the following cases:
- *
- * (1) Install primary CD, for normal DMA traffic (SSID = IOMMU_NO_PASID = 0).
- * (2) Install a secondary CD, for SID+SSID traffic.
- * (3) Update ASID of a CD. Atomically write the first 64 bits of the
- * CD, then invalidate the old entry and mappings.
- * (4) Quiesce the context without clearing the valid bit. Disable
- * translation, and ignore any translation fault.
- * (5) Remove a secondary CD.
- */
- u64 val;
- bool cd_live;
- struct arm_smmu_cd target;
- struct arm_smmu_cd *cdptr = &target;
- struct arm_smmu_cd *cd_table_entry;
- struct arm_smmu_ctx_desc_cfg *cd_table = &master->cd_table;
- struct arm_smmu_device *smmu = master->smmu;
-
- if (WARN_ON(ssid >= (1 << cd_table->s1cdmax)))
- return -E2BIG;
-
- cd_table_entry = arm_smmu_alloc_cd_ptr(master, ssid);
- if (!cd_table_entry)
- return -ENOMEM;
-
- target = *cd_table_entry;
- val = le64_to_cpu(cdptr->data[0]);
- cd_live = !!(val & CTXDESC_CD_0_V);
-
- if (!cd) { /* (5) */
- val = 0;
- } else if (cd == &quiet_cd) { /* (4) */
- if (!(smmu->features & ARM_SMMU_FEAT_STALL_FORCE))
- val &= ~(CTXDESC_CD_0_S | CTXDESC_CD_0_R);
- val |= CTXDESC_CD_0_TCR_EPD0;
- } else if (cd_live) { /* (3) */
- val &= ~CTXDESC_CD_0_ASID;
- val |= FIELD_PREP(CTXDESC_CD_0_ASID, cd->asid);
- /*
- * Until CD+TLB invalidation, both ASIDs may be used for tagging
- * this substream's traffic
- */
- } else { /* (1) and (2) */
- cdptr->data[1] = cpu_to_le64(cd->ttbr & CTXDESC_CD_1_TTB0_MASK);
- cdptr->data[2] = 0;
- cdptr->data[3] = cpu_to_le64(cd->mair);
-
- val = cd->tcr |
-#ifdef __BIG_ENDIAN
- CTXDESC_CD_0_ENDI |
-#endif
- CTXDESC_CD_0_R | CTXDESC_CD_0_A |
- (cd->mm ? 0 : CTXDESC_CD_0_ASET) |
- CTXDESC_CD_0_AA64 |
- FIELD_PREP(CTXDESC_CD_0_ASID, cd->asid) |
- CTXDESC_CD_0_V;
-
- if (cd_table->stall_enabled)
- val |= CTXDESC_CD_0_S;
- }
- cdptr->data[0] = cpu_to_le64(val);
- /*
- * Since the above is updating the CD entry based on the current value
- * without zeroing unused bits it needs fixing before being passed to
- * the programming logic.
- */
- arm_smmu_clean_cd_entry(&target);
- arm_smmu_write_cd_entry(master, ssid, cd_table_entry, &target);
- return 0;
-}
-
static int arm_smmu_alloc_cd_tables(struct arm_smmu_master *master)
{
int ret;
@@ -1438,7 +1350,6 @@ static int arm_smmu_alloc_cd_tables(struct arm_smmu_master *master)
struct arm_smmu_device *smmu = master->smmu;
struct arm_smmu_ctx_desc_cfg *cd_table = &master->cd_table;

- cd_table->stall_enabled = master->stall_enabled;
cd_table->s1cdmax = master->ssid_bits;
max_contexts = 1 << cd_table->s1cdmax;

@@ -1536,7 +1447,7 @@ arm_smmu_write_strtab_l1_desc(__le64 *dst, struct arm_smmu_strtab_l1_desc *desc)
val |= FIELD_PREP(STRTAB_L1_DESC_SPAN, desc->span);
val |= desc->l2ptr_dma & STRTAB_L1_DESC_L2PTR_MASK;

- /* See comment in arm_smmu_write_ctx_desc() */
+ /* The HW has 64 bit atomicity with stores to the L2 STE table */
WRITE_ONCE(*dst, cpu_to_le64(val));
}

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
index 99fd6f24caa818..8098bf8836a180 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -609,8 +609,6 @@ struct arm_smmu_ctx_desc_cfg {
u8 s1fmt;
/* log2 of the maximum number of CDs supported by this table */
u8 s1cdmax;
- /* Whether CD entries in this table have the stall bit set. */
- u8 stall_enabled:1;
};

struct arm_smmu_s2_cfg {
@@ -749,11 +747,12 @@ static inline struct arm_smmu_domain *to_smmu_domain(struct iommu_domain *dom)

extern struct xarray arm_smmu_asid_xa;
extern struct mutex arm_smmu_asid_lock;
-extern struct arm_smmu_ctx_desc quiet_cd;

void arm_smmu_clear_cd(struct arm_smmu_master *master, ioasid_t ssid);
struct arm_smmu_cd *arm_smmu_get_cd_ptr(struct arm_smmu_master *master,
u32 ssid);
+struct arm_smmu_cd *arm_smmu_alloc_cd_ptr(struct arm_smmu_master *master,
+ u32 ssid);
void arm_smmu_make_s1_cd(struct arm_smmu_cd *target,
struct arm_smmu_master *master,
struct arm_smmu_domain *smmu_domain);
@@ -761,8 +760,6 @@ void arm_smmu_write_cd_entry(struct arm_smmu_master *master, int ssid,
struct arm_smmu_cd *cdptr,
const struct arm_smmu_cd *target);

-int arm_smmu_write_ctx_desc(struct arm_smmu_master *smmu_master, int ssid,
- struct arm_smmu_ctx_desc *cd);
void arm_smmu_tlb_inv_asid(struct arm_smmu_device *smmu, u16 asid);
void arm_smmu_tlb_inv_range_asid(unsigned long iova, size_t size, int asid,
size_t granule, bool leaf,
--
2.43.2