linux-kernel - [PATCH 2/4] x86/mm: harmonize return value of phys_pte

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Message-ID: <20251003-x86-init-cleanup-v1-2-f2b7994c2ad6@google.com>
Date: Fri, 03 Oct 2025 16:56:42 +0000
From: Brendan Jackman <jackmanb@...gle.com>
To: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	"H. Peter Anvin" <hpa@...or.com>, Andy Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>
Cc: linux-kernel@...r.kernel.org, Brendan Jackman <jackmanb@...gle.com>
Subject: [PATCH 2/4] x86/mm: harmonize return value of phys_pte_init()

In the case that they encounter pre-existing mappings, all the other
phys_*_init()s include those pre-mapped PFNs in the returned value.
Excluding those PFNs only when they are mapped at 4K seems like an
error. So make it consistent.

The other functions only include the existing mappings if the
page_size_mask would have allowed creating those mappings.
4K pages can't be disabled by page_size_mask so that condition is not
needed here; paddr_last can be assigned unconditionally before checking
for existing mappings.

Signed-off-by: Brendan Jackman <jackmanb@...gle.com>
---
 arch/x86/mm/init_64.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 9e45b371a6234b41bd7177b81b5d432341ae7214..968a5092dbd7ee3e7007fa0c769eff7d7ecb0ba3 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -492,6 +492,8 @@ phys_pte_init(pte_t *pte_page, unsigned long paddr, unsigned long paddr_end,
 			continue;
 		}
 
+		paddr_last = paddr_next;
+
 		/*
 		 * We will re-use the existing mapping.
 		 * Xen for example has some special requirements, like mapping
@@ -506,7 +508,6 @@ phys_pte_init(pte_t *pte_page, unsigned long paddr, unsigned long paddr_end,
 
 		pages++;
 		set_pte_init(pte, pfn_pte(paddr >> PAGE_SHIFT, prot), init);
-		paddr_last = (paddr & PAGE_MASK) + PAGE_SIZE;
 	}
 
 	update_page_count(PG_LEVEL_4K, pages);

-- 
2.50.1