[PATCH v9 06/12] x86/mm: use INVLPGB for kernel TLB flushes

Rik van Riel
2025-02-06T04:44:16Z

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@surriel.com>
Tested-by: Manali Shukla <Manali.Shukla@amd.com>
---
arch/x86/mm/tlb.c | 28 +++++++++++++++++++++++++++-
1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 36939b104561..227e972b6fbc 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -1086,6 +1086,30 @@ void flush_tlb_all(void)
on_each_cpu(do_flush_tlb_all, NULL, 1);
}

+static bool broadcast_kernel_range_flush(struct flush_tlb_info *info)
+{
+ unsigned long addr;
+ unsigned long nr;
+
+ if (!IS_ENABLED(CONFIG_X86_BROADCAST_TLB_FLUSH))
+ return false;
+
+ if (!cpu_feature_enabled(X86_FEATURE_INVLPGB))
+ return false;
+
+ if (info->end == TLB_FLUSH_ALL) {
+ invlpgb_flush_all();
+ return true;
+ }
+
+ for (addr = info->start; addr < info->end; addr += nr << PAGE_SHIFT) {
+ nr = min((info->end - addr) >> PAGE_SHIFT, invlpgb_count_max);
+ invlpgb_flush_addr_nosync(addr, nr);
+ }
+ tlbsync();
+ return true;
+}
+
static void do_kernel_range_flush(void *info)
{
struct flush_tlb_info *f = info;
@@ -1105,7 +1129,9 @@ void flush_tlb_kernel_range(unsigned long start, unsigned long end)
info = get_flush_tlb_info(NULL, start, end, PAGE_SHIFT, false,
TLB_GENERATION_INVALID);

- if (info->end == TLB_FLUSH_ALL)
+ if (broadcast_kernel_range_flush(info))
+ ; /* Fall through. */
+ else if (info->end == TLB_FLUSH_ALL)
on_each_cpu(do_flush_tlb_all, NULL, 1);
else
on_each_cpu(do_kernel_range_flush, info, 1);
--
2.47.1