linux-kernel - [PATCH v14 04/13] x86/mm: use INVLPGB for kernel TLB flushes

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Message-ID: <20250226030129.530345-5-riel@surriel.com>
Date: Tue, 25 Feb 2025 22:00:39 -0500
From: Rik van Riel <riel@...riel.com>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org,
	bp@...en8.de,
	peterz@...radead.org,
	dave.hansen@...ux.intel.com,
	zhengqi.arch@...edance.com,
	nadav.amit@...il.com,
	thomas.lendacky@....com,
	kernel-team@...a.com,
	linux-mm@...ck.org,
	akpm@...ux-foundation.org,
	jackmanb@...gle.com,
	jannh@...gle.com,
	mhklinux@...look.com,
	andrew.cooper3@...rix.com,
	Manali.Shukla@....com,
	mingo@...nel.org,
	Rik van Riel <riel@...riel.com>
Subject: [PATCH v14 04/13] x86/mm: use INVLPGB for kernel TLB flushes

Use broadcast TLB invalidation for kernel addresses when available.

Remove the need to send IPIs for kernel TLB flushes.

Signed-off-by: Rik van Riel <riel@...riel.com>
Tested-by: Manali Shukla <Manali.Shukla@....com>
Tested-by: Brendan Jackman <jackmanb@...gle.com>
Tested-by: Michael Kelley <mhklinux@...look.com>
---
 arch/x86/mm/tlb.c | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index dbcb5c968ff9..f44a03bca41c 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -1077,6 +1077,18 @@ void flush_tlb_all(void)
 	on_each_cpu(do_flush_tlb_all, NULL, 1);
 }
 
+static void invlpgb_kernel_range_flush(struct flush_tlb_info *info)
+{
+	unsigned long addr, nr;
+
+	for (addr = info->start; addr < info->end; addr += nr << PAGE_SHIFT) {
+		nr = (info->end - addr) >> PAGE_SHIFT;
+		nr = clamp_val(nr, 1, invlpgb_count_max);
+		invlpgb_flush_addr_nosync(addr, nr);
+	}
+	__tlbsync();
+}
+
 static void do_kernel_range_flush(void *info)
 {
 	struct flush_tlb_info *f = info;
@@ -1087,6 +1099,22 @@ static void do_kernel_range_flush(void *info)
 		flush_tlb_one_kernel(addr);
 }
 
+static void kernel_tlb_flush_all(struct flush_tlb_info *info)
+{
+	if (cpu_feature_enabled(X86_FEATURE_INVLPGB))
+		invlpgb_flush_all();
+	else
+		on_each_cpu(do_flush_tlb_all, NULL, 1);
+}
+
+static void kernel_tlb_flush_range(struct flush_tlb_info *info)
+{
+	if (cpu_feature_enabled(X86_FEATURE_INVLPGB))
+		invlpgb_kernel_range_flush(info);
+	else
+		on_each_cpu(do_kernel_range_flush, info, 1);
+}
+
 void flush_tlb_kernel_range(unsigned long start, unsigned long end)
 {
 	struct flush_tlb_info *info;
@@ -1097,9 +1125,9 @@ void flush_tlb_kernel_range(unsigned long start, unsigned long end)
 				  TLB_GENERATION_INVALID);
 
 	if (info->end == TLB_FLUSH_ALL)
-		on_each_cpu(do_flush_tlb_all, NULL, 1);
+		kernel_tlb_flush_all(info);
 	else
-		on_each_cpu(do_kernel_range_flush, info, 1);
+		kernel_tlb_flush_range(info);
 
 	put_flush_tlb_info();
 }
-- 
2.47.1