[PATCH v13 05/14] x86/mm: use INVLPGB in flush_tlb_all

Rik van Riel
2025-02-23T19:50:12Z

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@surriel.com>
Tested-by: Manali Shukla <Manali.Shukla@amd.com>
Tested-by: Brendan Jackman <jackmanb@google.com>
Tested-by: Michael Kelley <mhklinux@outlook.com>
---
arch/x86/mm/tlb.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 59396a3c6e9c..2d7ed0fda61f 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -1065,6 +1065,16 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
}

+static bool broadcast_flush_tlb_all(void)
+{
+ if (!cpu_feature_enabled(X86_FEATURE_INVLPGB))
+ return false;
+
+ guard(preempt)();
+ invlpgb_flush_all();
+ return true;
+}
+
static void do_flush_tlb_all(void *info)
{
count_vm_tlb_event(NR_TLB_REMOTE_FLUSH_RECEIVED);
@@ -1074,6 +1084,12 @@ 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 (broadcast_flush_tlb_all())
+ return;
+
+ /* Fall back to the IPI-based invalidation. */
on_each_cpu(do_flush_tlb_all, NULL, 1);
}

--
2.47.1