On 2021-06-18 03:51, Sai Prakash Ranjan wrote:
Add a quirk IO_PGTABLE_QUIRK_TLB_INV_ALL to invalidate entire context
with tlb_flush_all() callback in partial walk flush to improve unmap
performance on select few platforms where the cost of over-invalidation
is less than the unmap latency.
I still think this doesn't belong anywhere near io-pgtable at all. It's
a driver-internal decision how exactly it implements a non-leaf
invalidation, and that may be more complex than a predetermined boolean
decision. For example, I've just realised for SMMUv3 we can't invalidate
multiple levels of table at once with a range command, since if we
assume the whole thing is mapped at worst-case page granularity we may
fail to invalidate any parts which are mapped as intermediate-level
blocks. If invalidating a 1GB region (with 4KB granule) means having to
fall back to 256K non-range commands, we may not want to invalidate by
VA then, even though doing so for a 2MB region is still optimal.
It's also quite feasible that drivers might want to do this for leaf
invalidations too - if you don't like issuing 512 commands to invalidate
2MB, do you like issuing 511 commands to invalidate 2044KB? - and at
that point the logic really has to be in the driver anyway.
Robin.
Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
---
drivers/iommu/io-pgtable-arm.c | 3 ++-
include/linux/io-pgtable.h | 5 +++++
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index 87def58e79b5..5d362f2214bd 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -768,7 +768,8 @@ arm_64_lpae_alloc_pgtable_s1(struct io_pgtable_cfg *cfg, void *cookie)
if (cfg->quirks & ~(IO_PGTABLE_QUIRK_ARM_NS |
IO_PGTABLE_QUIRK_NON_STRICT |
IO_PGTABLE_QUIRK_ARM_TTBR1 |
- IO_PGTABLE_QUIRK_ARM_OUTER_WBWA))
+ IO_PGTABLE_QUIRK_ARM_OUTER_WBWA |
+ IO_PGTABLE_QUIRK_TLB_INV_ALL))
return NULL;
data = arm_lpae_alloc_pgtable(cfg);
diff --git a/include/linux/io-pgtable.h b/include/linux/io-pgtable.h
index 4d40dfa75b55..45441592a0e6 100644
--- a/include/linux/io-pgtable.h
+++ b/include/linux/io-pgtable.h
@@ -82,6 +82,10 @@ struct io_pgtable_cfg {
*
* IO_PGTABLE_QUIRK_ARM_OUTER_WBWA: Override the outer-cacheability
* attributes set in the TCR for a non-coherent page-table walker.
+ *
+ * IO_PGTABLE_QUIRK_TLB_INV_ALL: Use TLBIALL/TLBIASID to invalidate
+ * entire context for partial walk flush to increase unmap
+ * performance on select few platforms.
*/
#define IO_PGTABLE_QUIRK_ARM_NS BIT(0)
#define IO_PGTABLE_QUIRK_NO_PERMS BIT(1)
@@ -89,6 +93,7 @@ struct io_pgtable_cfg {
#define IO_PGTABLE_QUIRK_NON_STRICT BIT(4)
#define IO_PGTABLE_QUIRK_ARM_TTBR1 BIT(5)
#define IO_PGTABLE_QUIRK_ARM_OUTER_WBWA BIT(6)
+ #define IO_PGTABLE_QUIRK_TLB_INV_ALL BIT(7)
unsigned long quirks;
unsigned long pgsize_bitmap;
unsigned int ias;
