linux-kernel - [PATCH v4 12/12] x86/mm: only invalidate final translations with INVLPGB

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Message-ID: <20250112155453.1104139-13-riel@surriel.com>
Date: Sun, 12 Jan 2025 10:53:56 -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,
	jannh@...gle.com,
	Rik van Riel <riel@...riel.com>
Subject: [PATCH v4 12/12] x86/mm: only invalidate final translations with INVLPGB

Use the INVLPGB_FINAL_ONLY flag when invalidating mappings with INVPLGB.
This way only leaf mappings get removed from the TLB, leaving intermediate
translations cached.

On the (rare) occasions where we free page tables we do a full flush,
ensuring intermediate translations get flushed from the TLB.

Signed-off-by: Rik van Riel <riel@...riel.com>
---
 arch/x86/include/asm/invlpgb.h | 10 ++++++++--
 arch/x86/mm/tlb.c              |  8 ++++----
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/invlpgb.h b/arch/x86/include/asm/invlpgb.h
index d62e3733a1ab..4fa48d063b76 100644
--- a/arch/x86/include/asm/invlpgb.h
+++ b/arch/x86/include/asm/invlpgb.h
@@ -61,9 +61,15 @@ static inline void invlpgb_flush_user(unsigned long pcid,
 
 static inline void invlpgb_flush_user_nr_nosync(unsigned long pcid,
 						unsigned long addr,
-						int nr, bool pmd_stride)
+						int nr, bool pmd_stride,
+						bool freed_tables)
 {
-	__invlpgb(0, pcid, addr, nr - 1, pmd_stride, INVLPGB_PCID | INVLPGB_VA);
+	unsigned long flags = INVLPGB_PCID | INVLPGB_VA;
+
+	if (!freed_tables)
+		flags |= INVLPGB_FINAL_ONLY;
+
+	__invlpgb(0, pcid, addr, nr - 1, pmd_stride, flags);
 }
 
 /* Flush all mappings for a given PCID, not including globals. */
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 532911fbb12a..0254e9ebaf15 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -538,10 +538,10 @@ static void broadcast_tlb_flush(struct flush_tlb_info *info)
 		nr = min(maxnr, (info->end - addr) >> info->stride_shift);
 		nr = max(nr, 1);
 
-		invlpgb_flush_user_nr_nosync(kern_pcid(asid), addr, nr, pmd);
+		invlpgb_flush_user_nr_nosync(kern_pcid(asid), addr, nr, pmd, info->freed_tables);
 		/* Do any CPUs supporting INVLPGB need PTI? */
 		if (static_cpu_has(X86_FEATURE_PTI))
-			invlpgb_flush_user_nr_nosync(user_pcid(asid), addr, nr, pmd);
+			invlpgb_flush_user_nr_nosync(user_pcid(asid), addr, nr, pmd, info->freed_tables);
 		addr += nr << info->stride_shift;
 	} while (addr < info->end);
 
@@ -1699,10 +1699,10 @@ void arch_tlbbatch_add_pending(struct arch_tlbflush_unmap_batch *batch,
 			batch->used_invlpgb = true;
 			migrate_disable();
 		}
-		invlpgb_flush_user_nr_nosync(kern_pcid(asid), uaddr, 1, false);
+		invlpgb_flush_user_nr_nosync(kern_pcid(asid), uaddr, 1, false, false);
 		/* Do any CPUs supporting INVLPGB need PTI? */
 		if (static_cpu_has(X86_FEATURE_PTI))
-			invlpgb_flush_user_nr_nosync(user_pcid(asid), uaddr, 1, false);
+			invlpgb_flush_user_nr_nosync(user_pcid(asid), uaddr, 1, false, false);
 	} else {
 		inc_mm_tlb_gen(mm);
 		cpumask_or(&batch->cpumask, &batch->cpumask, mm_cpumask(mm));
-- 
2.47.1