linux-kernel - [PATCH v14 05/13] x86/mm: use INVLPGB in flush_tlb

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Message-ID: <20250226030129.530345-6-riel@surriel.com>
Date: Tue, 25 Feb 2025 22:00:40 -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 05/13] x86/mm: use INVLPGB in flush_tlb_all

The flush_tlb_all() function is not used a whole lot, but we might
as well use broadcast TLB flushing there, too.

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 | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index f44a03bca41c..a6cd61d5f423 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -1064,7 +1064,6 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
 	mmu_notifier_arch_invalidate_secondary_tlbs(mm, start, end);
 }
 
-
 static void do_flush_tlb_all(void *info)
 {
 	count_vm_tlb_event(NR_TLB_REMOTE_FLUSH_RECEIVED);
@@ -1074,6 +1073,15 @@ static void do_flush_tlb_all(void *info)
 void flush_tlb_all(void)
 {
 	count_vm_tlb_event(NR_TLB_REMOTE_FLUSH);
+
+	/* First try (faster) hardware-assisted TLB invalidation. */
+	if (cpu_feature_enabled(X86_FEATURE_INVLPGB)) {
+		guard(preempt)();
+		invlpgb_flush_all();
+		return;
+	}
+
+	/* Fall back to the IPI-based invalidation. */
 	on_each_cpu(do_flush_tlb_all, NULL, 1);
 }
 
-- 
2.47.1