linux-kernel - [RFC PATCH 5/9] x86/mm: Change cpa_flush() to call flush_kernel

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Message-ID: <20250506003811.92405-6-riel@surriel.com>
Date: Mon,  5 May 2025 20:37:43 -0400
From: Rik van Riel <riel@...riel.com>
To: linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org,
	x86@...nel.org,
	kernel-team@...a.com,
	dave.hansen@...ux.intel.com,
	luto@...nel.org,
	peterz@...radead.org,
	tglx@...utronix.de,
	mingo@...hat.com,
	bp@...en8.de,
	hpa@...or.com,
	Rik van Riel <riel@...com>,
	Yu-cheng Yu <yu-cheng.yu@...el.com>,
	Rik van Riel <riel@...riel.com>
Subject: [RFC PATCH 5/9] x86/mm: Change cpa_flush() to call flush_kernel_range() directly

From: Rik van Riel <riel@...com>

The function cpa_flush() calls __flush_tlb_one_kernel() and
flush_tlb_all().

Replacing that with a call to flush_tlb_kernel_range() allows
cpa_flush() to make use of INVLPGB or RAR without any additional
changes.

Initialize invlpgb_count_max to 1, since flush_tlb_kernel_range()
can now be called before invlpgb_count_max has been initialized
to the value read from CPUID.

[riel: remove now unused __cpa_flush_tlb]

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@...el.com>
Signed-off-by: Rik van Riel <riel@...riel.com>
---
 arch/x86/kernel/cpu/amd.c    |  2 +-
 arch/x86/mm/pat/set_memory.c | 20 +++++++-------------
 2 files changed, 8 insertions(+), 14 deletions(-)

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 13a48ec28f32..c85ecde786f3 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -31,7 +31,7 @@
 
 #include "cpu.h"
 
-u16 invlpgb_count_max __ro_after_init;
+u16 invlpgb_count_max __ro_after_init = 1;
 
 static inline int rdmsrq_amd_safe(unsigned msr, u64 *p)
 {
diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
index 30ab4aced761..2454f5249329 100644
--- a/arch/x86/mm/pat/set_memory.c
+++ b/arch/x86/mm/pat/set_memory.c
@@ -399,15 +399,6 @@ static void cpa_flush_all(unsigned long cache)
 	on_each_cpu(__cpa_flush_all, (void *) cache, 1);
 }
 
-static void __cpa_flush_tlb(void *data)
-{
-	struct cpa_data *cpa = data;
-	unsigned int i;
-
-	for (i = 0; i < cpa->numpages; i++)
-		flush_tlb_one_kernel(fix_addr(__cpa_addr(cpa, i)));
-}
-
 static int collapse_large_pages(unsigned long addr, struct list_head *pgtables);
 
 static void cpa_collapse_large_pages(struct cpa_data *cpa)
@@ -444,6 +435,7 @@ static void cpa_collapse_large_pages(struct cpa_data *cpa)
 
 static void cpa_flush(struct cpa_data *cpa, int cache)
 {
+	unsigned long start, end;
 	unsigned int i;
 
 	BUG_ON(irqs_disabled() && !early_boot_irqs_disabled);
@@ -453,10 +445,12 @@ static void cpa_flush(struct cpa_data *cpa, int cache)
 		goto collapse_large_pages;
 	}
 
-	if (cpa->force_flush_all || cpa->numpages > tlb_single_page_flush_ceiling)
-		flush_tlb_all();
-	else
-		on_each_cpu(__cpa_flush_tlb, cpa, 1);
+	start = fix_addr(__cpa_addr(cpa, 0));
+	end = fix_addr(__cpa_addr(cpa, cpa->numpages));
+	if (cpa->force_flush_all)
+		end = TLB_FLUSH_ALL;
+
+	flush_tlb_kernel_range(start, end);
 
 	if (!cache)
 		goto collapse_large_pages;
-- 
2.49.0