[RFC PATCH v5 0/2] arm64: tlb: add support for TLBI RANGE instructions

[Zhenyu Ye]

ARMv8.4-TLBI provides TLBI invalidation instruction that apply to a
range of input addresses. This series add support for this feature.

I tested this feature on a FPGA machine whose cpus support the tlbi range.
As the page num increases, the performance is improved significantly. When
page num = 256, the performance is improved by about 10 times.

Below is the test data when the stride = PTE:

	[page num]	[classic]		[tlbi range]
	1		16051			13524
	2		11366			11146
	3		11582			12171
	4		11694			11101
	5		12138			12267
	6		12290			11105
	7		12400			12002
	8		12837			11097
	9		14791			12140
	10		15461			11087
	16		18233			11094
	32		26983			11079
	64		43840			11092
	128		77754			11098
	256		145514			11089
	512		280932			11111

See more details in:

https://lore.kernel.org/linux-arm-kernel/504c7588-97e5-e014-fca0-c5511ae0d256@huawei.com/

--
ChangeList:
v5:
- rebase this series on Linux 5.8-rc4.
- remove the __TG macro.
- move the odd range_pages check into loop.

v4:
combine the __flush_tlb_range() and the __directly into the same function
with a single loop for both.

v3:
rebase this series on Linux 5.7-rc1.

v2:
Link: https://lkml.org/lkml/2019/11/11/348

Zhenyu Ye (2):
  arm64: tlb: Detect the ARMv8.4 TLBI RANGE feature
  arm64: tlb: Use the TLBI RANGE feature in arm64

 arch/arm64/include/asm/cpucaps.h  |   3 +-
 arch/arm64/include/asm/sysreg.h   |   3 +
 arch/arm64/include/asm/tlbflush.h | 101 +++++++++++++++++++++++++-----
 arch/arm64/kernel/cpufeature.c    |  10 +++
 4 files changed, 102 insertions(+), 15 deletions(-)

-- 
2.19.1