Re: [PATCH v4 3/5] iommu/io-pgtable-arm: add support for non-strict mode

From: Robin Murphy
Date: Thu Aug 09 2018 - 06:54:47 EST


On 06/08/18 13:27, Zhen Lei wrote:
To support the non-strict mode, now we only tlbi and sync for the strict
mode. But for the non-leaf case, always follow strict mode.

Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
---
drivers/iommu/io-pgtable-arm.c | 27 ++++++++++++++++++---------
drivers/iommu/io-pgtable.h | 3 +++
2 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index 010a254..bb61bef 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -292,7 +292,7 @@ static void __arm_lpae_set_pte(arm_lpae_iopte *ptep, arm_lpae_iopte pte,

static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data,
unsigned long iova, size_t size, int lvl,
- arm_lpae_iopte *ptep);
+ arm_lpae_iopte *ptep, bool strict);

static void __arm_lpae_init_pte(struct arm_lpae_io_pgtable *data,
phys_addr_t paddr, arm_lpae_iopte prot,
@@ -319,6 +319,7 @@ static int arm_lpae_init_pte(struct arm_lpae_io_pgtable *data,
arm_lpae_iopte prot, int lvl,
arm_lpae_iopte *ptep)
{
+ size_t unmapped;
arm_lpae_iopte pte = *ptep;

if (iopte_leaf(pte, lvl)) {
@@ -334,7 +335,8 @@ static int arm_lpae_init_pte(struct arm_lpae_io_pgtable *data,
size_t sz = ARM_LPAE_BLOCK_SIZE(lvl, data);

tblp = ptep - ARM_LPAE_LVL_IDX(iova, lvl, data);
- if (WARN_ON(__arm_lpae_unmap(data, iova, sz, lvl, tblp) != sz))
+ unmapped = __arm_lpae_unmap(data, iova, sz, lvl, tblp, true);
+ if (WARN_ON(unmapped != sz))

What's the extra local variable for?

return -EINVAL;
}

@@ -576,15 +578,17 @@ static size_t arm_lpae_split_blk_unmap(struct arm_lpae_io_pgtable *data,
}

if (unmap_idx < 0)
- return __arm_lpae_unmap(data, iova, size, lvl, tablep);
+ return __arm_lpae_unmap(data, iova, size, lvl, tablep, true);

io_pgtable_tlb_add_flush(&data->iop, iova, size, size, true);
+ io_pgtable_tlb_sync(&data->iop);
+
return size;
}

static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data,
unsigned long iova, size_t size, int lvl,
- arm_lpae_iopte *ptep)
+ arm_lpae_iopte *ptep, bool strict)
{
arm_lpae_iopte pte;
struct io_pgtable *iop = &data->iop;
@@ -609,7 +613,7 @@ static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data,
io_pgtable_tlb_sync(iop);
ptep = iopte_deref(pte, data);
__arm_lpae_free_pgtable(data, lvl + 1, ptep);
- } else {
+ } else if (strict) {

Since this is the only place we ever actually evaluate "strict", can't we just test iop->cfg.quirks directly at this point instead of playing pass-the-parcel with the extra argument?

Robin.

io_pgtable_tlb_add_flush(iop, iova, size, size, true);
}

@@ -625,12 +629,13 @@ static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data,

/* Keep on walkin' */
ptep = iopte_deref(pte, data);
- return __arm_lpae_unmap(data, iova, size, lvl + 1, ptep);
+ return __arm_lpae_unmap(data, iova, size, lvl + 1, ptep, strict);
}

static size_t arm_lpae_unmap(struct io_pgtable_ops *ops, unsigned long iova,
size_t size)
{
+ bool strict;
struct arm_lpae_io_pgtable *data = io_pgtable_ops_to_data(ops);
arm_lpae_iopte *ptep = data->pgd;
int lvl = ARM_LPAE_START_LVL(data);
@@ -638,7 +643,9 @@ static size_t arm_lpae_unmap(struct io_pgtable_ops *ops, unsigned long iova,
if (WARN_ON(iova >= (1ULL << data->iop.cfg.ias)))
return 0;

- return __arm_lpae_unmap(data, iova, size, lvl, ptep);
+ strict = !(data->iop.cfg.quirks & IO_PGTABLE_QUIRK_NON_STRICT);
+
+ return __arm_lpae_unmap(data, iova, size, lvl, ptep, strict);
}

static phys_addr_t arm_lpae_iova_to_phys(struct io_pgtable_ops *ops,
@@ -771,7 +778,8 @@ static void arm_lpae_restrict_pgsizes(struct io_pgtable_cfg *cfg)
u64 reg;
struct arm_lpae_io_pgtable *data;

- if (cfg->quirks & ~(IO_PGTABLE_QUIRK_ARM_NS | IO_PGTABLE_QUIRK_NO_DMA))
+ if (cfg->quirks & ~(IO_PGTABLE_QUIRK_ARM_NS | IO_PGTABLE_QUIRK_NO_DMA |
+ IO_PGTABLE_QUIRK_NON_STRICT))
return NULL;

data = arm_lpae_alloc_pgtable(cfg);
@@ -863,7 +871,8 @@ static void arm_lpae_restrict_pgsizes(struct io_pgtable_cfg *cfg)
struct arm_lpae_io_pgtable *data;

/* The NS quirk doesn't apply at stage 2 */
- if (cfg->quirks & ~IO_PGTABLE_QUIRK_NO_DMA)
+ if (cfg->quirks & ~(IO_PGTABLE_QUIRK_NO_DMA |
+ IO_PGTABLE_QUIRK_NON_STRICT))
return NULL;

data = arm_lpae_alloc_pgtable(cfg);
diff --git a/drivers/iommu/io-pgtable.h b/drivers/iommu/io-pgtable.h
index 2df7909..beb14a3 100644
--- a/drivers/iommu/io-pgtable.h
+++ b/drivers/iommu/io-pgtable.h
@@ -71,12 +71,15 @@ struct io_pgtable_cfg {
* be accessed by a fully cache-coherent IOMMU or CPU (e.g. for a
* software-emulated IOMMU), such that pagetable updates need not
* be treated as explicit DMA data.
+ * IO_PGTABLE_QUIRK_NON_STRICT: Put off TLBs invalidation and release
+ * memory first.
*/
#define IO_PGTABLE_QUIRK_ARM_NS BIT(0)
#define IO_PGTABLE_QUIRK_NO_PERMS BIT(1)
#define IO_PGTABLE_QUIRK_TLBI_ON_MAP BIT(2)
#define IO_PGTABLE_QUIRK_ARM_MTK_4GB BIT(3)
#define IO_PGTABLE_QUIRK_NO_DMA BIT(4)
+ #define IO_PGTABLE_QUIRK_NON_STRICT BIT(5)
unsigned long quirks;
unsigned long pgsize_bitmap;
unsigned int ias;
--
1.8.3