[PATCH 2/2] arm64: tlb: Add boot parameter to disable TLB flush within the same inner shareable domain

[Takao Indoh]

From: Takao Indoh <indou.takao@xxxxxxxxxxx>

This patch adds new boot parameter 'disable_tlbflush_is' to disable TLB
flush within the same inner shareable domain for performance tuning.

In the case of flush_tlb_mm() *without* this parameter, TLB entry is
invalidated by __tlbi(aside1is, asid). By this instruction, all CPUs within
the same inner shareable domain check if there are TLB entries which have
this ASID, this causes performance noise, especially at large-scale HPC
environment, which has more than thousand nodes with low latency
interconnect.

When this new parameter is specified, TLB entry is invalidated by
__tlbi(aside1, asid) only on the CPUs specified by mm_cpumask(mm).
Therefore TLB flush is done on minimal CPUs and performance problem does
not occur.

Signed-off-by: QI Fuli <qi.fuli@xxxxxxxxxxx>
Signed-off-by: Takao Indoh <indou.takao@xxxxxxxxxxx>
---
 .../admin-guide/kernel-parameters.txt         |   4 +
 arch/arm64/include/asm/tlbflush.h             |  61 ++-----
 arch/arm64/kernel/Makefile                    |   2 +-
 arch/arm64/kernel/tlbflush.c                  | 155 ++++++++++++++++++
 4 files changed, 172 insertions(+), 50 deletions(-)
 create mode 100644 arch/arm64/kernel/tlbflush.c

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 138f6664b2e2..a693eea34e48 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -848,6 +848,10 @@
 	disable=	[IPV6]
 			See Documentation/networking/ipv6.txt.
 
+	disable_tlbflush_is
+			[ARM64] Disable using TLB instruction to flush
+			all PE within the same inner shareable domain.
+
 	hardened_usercopy=
                         [KNL] Under CONFIG_HARDENED_USERCOPY, whether
                         hardening is enabled for this boot. Hardened
diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
index dff8f9ea5754..ba2b3fd0b63c 100644
--- a/arch/arm64/include/asm/tlbflush.h
+++ b/arch/arm64/include/asm/tlbflush.h
@@ -139,6 +139,13 @@
  *	on top of these routines, since that is our interface to the mmu_gather
  *	API as used by munmap() and friends.
  */
+
+void flush_tlb_mm(struct mm_struct *mm);
+void flush_tlb_page_nosync(struct vm_area_struct *vma,
+				unsigned long uaddr);
+void __flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
+		unsigned long end, unsigned long stride, bool last_level);
+
 static inline void local_flush_tlb_all(void)
 {
 	dsb(nshst);
@@ -155,24 +162,14 @@ static inline void flush_tlb_all(void)
 	isb();
 }
 
-static inline void flush_tlb_mm(struct mm_struct *mm)
+static inline void local_flush_tlb_mm(struct mm_struct *mm)
 {
 	unsigned long asid = __TLBI_VADDR(0, ASID(mm));
 
-	dsb(ishst);
-	__tlbi(aside1is, asid);
-	__tlbi_user(aside1is, asid);
-	dsb(ish);
-}
-
-static inline void flush_tlb_page_nosync(struct vm_area_struct *vma,
-					 unsigned long uaddr)
-{
-	unsigned long addr = __TLBI_VADDR(uaddr, ASID(vma->vm_mm));
-
-	dsb(ishst);
-	__tlbi(vale1is, addr);
-	__tlbi_user(vale1is, addr);
+	dsb(nshst);
+	__tlbi(aside1, asid);
+	__tlbi_user(aside1, asid);
+	dsb(nsh);
 }
 
 static inline void flush_tlb_page(struct vm_area_struct *vma,
@@ -188,40 +185,6 @@ static inline void flush_tlb_page(struct vm_area_struct *vma,
  */
 #define MAX_TLBI_OPS	PTRS_PER_PTE
 
-static inline void __flush_tlb_range(struct vm_area_struct *vma,
-				     unsigned long start, unsigned long end,
-				     unsigned long stride, bool last_level)
-{
-	unsigned long asid = ASID(vma->vm_mm);
-	unsigned long addr;
-
-	start = round_down(start, stride);
-	end = round_up(end, stride);
-
-	if ((end - start) >= (MAX_TLBI_OPS * stride)) {
-		flush_tlb_mm(vma->vm_mm);
-		return;
-	}
-
-	/* Convert the stride into units of 4k */
-	stride >>= 12;
-
-	start = __TLBI_VADDR(start, asid);
-	end = __TLBI_VADDR(end, asid);
-
-	dsb(ishst);
-	for (addr = start; addr < end; addr += stride) {
-		if (last_level) {
-			__tlbi(vale1is, addr);
-			__tlbi_user(vale1is, addr);
-		} else {
-			__tlbi(vae1is, addr);
-			__tlbi_user(vae1is, addr);
-		}
-	}
-	dsb(ish);
-}
-
 static inline void flush_tlb_range(struct vm_area_struct *vma,
 				   unsigned long start, unsigned long end)
 {
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 9e7dcb2c31c7..266c9a57b081 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -19,7 +19,7 @@ obj-y			:= debug-monitors.o entry.o irq.o fpsimd.o		\
 			   return_address.o cpuinfo.o cpu_errata.o		\
 			   cpufeature.o alternative.o cacheinfo.o		\
 			   smp.o smp_spin_table.o topology.o smccc-call.o	\
-			   syscall.o
+			   syscall.o tlbflush.o
 
 extra-$(CONFIG_EFI)			:= efi-entry.o
 
diff --git a/arch/arm64/kernel/tlbflush.c b/arch/arm64/kernel/tlbflush.c
new file mode 100644
index 000000000000..52c9a237759a
--- /dev/null
+++ b/arch/arm64/kernel/tlbflush.c
@@ -0,0 +1,155 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2019 FUJITSU LIMITED
+
+#include <linux/smp.h>
+#include <asm/tlbflush.h>
+
+struct tlb_args {
+	struct vm_area_struct *ta_vma;
+	unsigned long ta_start;
+	unsigned long ta_end;
+	unsigned long ta_stride;
+	bool ta_last_level;
+};
+
+int disable_tlbflush_is;
+
+static int __init disable_tlbflush_is_setup(char *str)
+{
+	disable_tlbflush_is = 1;
+
+	return 0;
+}
+__setup("disable_tlbflush_is", disable_tlbflush_is_setup);
+
+static inline void __flush_tlb_mm(struct mm_struct *mm)
+{
+	unsigned long asid = __TLBI_VADDR(0, ASID(mm));
+
+	dsb(ishst);
+	__tlbi(aside1is, asid);
+	__tlbi_user(aside1is, asid);
+	dsb(ish);
+}
+
+static inline void ipi_flush_tlb_mm(void *arg)
+{
+	struct mm_struct *mm = arg;
+
+	local_flush_tlb_mm(mm);
+}
+
+void flush_tlb_mm(struct mm_struct *mm)
+{
+	if (disable_tlbflush_is)
+		on_each_cpu_mask(mm_cpumask(mm), ipi_flush_tlb_mm,
+				 (void *)mm, true);
+	else
+		__flush_tlb_mm(mm);
+}
+
+static inline void __flush_tlb_page_nosync(unsigned long addr)
+{
+	dsb(ishst);
+	__tlbi(vale1is, addr);
+	__tlbi_user(vale1is, addr);
+}
+
+static inline void __local_flush_tlb_page_nosync(unsigned long addr)
+{
+	dsb(nshst);
+	__tlbi(vale1, addr);
+	__tlbi_user(vale1, addr);
+	dsb(nsh);
+}
+
+static inline void ipi_flush_tlb_page_nosync(void *arg)
+{
+	unsigned long addr = *(unsigned long *)arg;
+
+	__local_flush_tlb_page_nosync(addr);
+}
+
+void flush_tlb_page_nosync(struct vm_area_struct *vma, unsigned long uaddr)
+{
+	unsigned long addr = __TLBI_VADDR(uaddr, ASID(vma->vm_mm));
+
+	if (disable_tlbflush_is)
+		on_each_cpu_mask(mm_cpumask(vma->vm_mm),
+				ipi_flush_tlb_page_nosync, &addr, true);
+	else
+		__flush_tlb_page_nosync(addr);
+}
+
+static inline void ___flush_tlb_range(unsigned long start, unsigned long end,
+				     unsigned long stride, bool last_level)
+{
+	unsigned long addr;
+
+	dsb(ishst);
+	for (addr = start; addr < end; addr += stride) {
+		if (last_level) {
+			__tlbi(vale1is, addr);
+			__tlbi_user(vale1is, addr);
+		} else {
+			__tlbi(vae1is, addr);
+			__tlbi_user(vae1is, addr);
+		}
+	}
+	dsb(ish);
+}
+
+static inline void __local_flush_tlb_range(unsigned long addr, bool last_level)
+{
+	dsb(nshst);
+	if (last_level) {
+		__tlbi(vale1, addr);
+		__tlbi_user(vale1, addr);
+	} else {
+		__tlbi(vae1, addr);
+		__tlbi_user(vae1, addr);
+	}
+	dsb(nsh);
+}
+
+static inline void ipi_flush_tlb_range(void *arg)
+{
+	struct tlb_args *ta = (struct tlb_args *)arg;
+	unsigned long addr;
+
+	for (addr = ta->ta_start; addr < ta->ta_end; addr += ta->ta_stride)
+		__local_flush_tlb_range(addr, ta->ta_last_level);
+}
+
+void __flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
+		unsigned long end, unsigned long stride, bool last_level)
+{
+	unsigned long asid = ASID(vma->vm_mm);
+
+	start = round_down(start, stride);
+	end = round_up(end, stride);
+
+	if ((end - start) >= (MAX_TLBI_OPS * stride)) {
+		flush_tlb_mm(vma->vm_mm);
+		return;
+	}
+
+	/* Convert the stride into units of 4k */
+	stride >>= 12;
+
+	start = __TLBI_VADDR(start, asid);
+	end = __TLBI_VADDR(end, asid);
+
+	if (disable_tlbflush_is) {
+		struct tlb_args ta = {
+			.ta_start	= start,
+			.ta_end		= end,
+			.ta_stride	= stride,
+			.ta_last_level	= last_level,
+		};
+
+		on_each_cpu_mask(mm_cpumask(vma->vm_mm), ipi_flush_tlb_range,
+					    &ta, true);
+	} else
+		___flush_tlb_range(start, end, stride, last_level);
+}
-- 
2.20.1