[PATCH v12 06/16] x86/mm: use INVLPGB for kernel TLB flushes

[Rik van Riel <riel@surriel.com>]

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>
Reviewed-by: Nadav Amit <nadav.amit@gmail.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 | 34 ++++++++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index dbcb5c968ff9..59396a3c6e9c 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -1077,6 +1077,20 @@ void flush_tlb_all(void)
 	on_each_cpu(do_flush_tlb_all, NULL, 1);
 }
 
+static bool invlpgb_kernel_range_flush(struct flush_tlb_info *info)
+{
+	unsigned long addr;
+	unsigned long 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();
+	return true;
+}
+
 static void do_kernel_range_flush(void *info)
 {
 	struct flush_tlb_info *f = info;
@@ -1087,6 +1101,22 @@ 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 +1127,9 @@ 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