__kernel_physical_mapping_init() will soon need to work on multiple
PGDs, so factor out something similar to phys_p4d_init() and friends,
which takes the base of the PGD as an argument.

Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
 arch/x86/mm/init_64.c | 33 +++++++++++++++++++++++----------
 1 file changed, 23 insertions(+), 10 deletions(-)

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 0e4270e20fadb578c7fd6bf5c5e4762027c36c45..e98e85cf15f42db669696ba8195d8fc633351b26 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -741,21 +741,20 @@ phys_p4d_init(p4d_t *p4d_page, unsigned long paddr, unsigned long paddr_end,
 }
 
 static unsigned long __meminit
-__kernel_physical_mapping_init(unsigned long paddr_start,
-			       unsigned long paddr_end,
-			       unsigned long page_size_mask,
-			       pgprot_t prot, bool init)
+phys_pgd_init(pgd_t *pgd_page, unsigned long paddr_start, unsigned long paddr_end,
+	      unsigned long page_size_mask, pgprot_t prot, bool init, bool *pgd_changed)
 {
-	bool pgd_changed = false;
 	unsigned long vaddr, vaddr_start, vaddr_end, vaddr_next, paddr_last;
 
+	*pgd_changed = false;
+
 	paddr_last = paddr_end;
 	vaddr = (unsigned long)__va(paddr_start);
 	vaddr_end = (unsigned long)__va(paddr_end);
 	vaddr_start = vaddr;
 
 	for (; vaddr < vaddr_end; vaddr = vaddr_next) {
-		pgd_t *pgd = pgd_offset_k(vaddr);
+		pgd_t *pgd = pgd_offset_pgd(pgd_page, vaddr);
 		p4d_t *p4d;
 
 		vaddr_next = (vaddr & PGDIR_MASK) + PGDIR_SIZE;
@@ -781,15 +780,29 @@ __kernel_physical_mapping_init(unsigned long paddr_start,
 					  (pud_t *) p4d, init);
 
 		spin_unlock(&init_mm.page_table_lock);
-		pgd_changed = true;
+		*pgd_changed = true;
 	}
 
-	if (pgd_changed)
-		sync_global_pgds(vaddr_start, vaddr_end - 1);
-
 	return paddr_last;
 }
 
+static unsigned long __meminit
+__kernel_physical_mapping_init(unsigned long paddr_start,
+			       unsigned long paddr_end,
+			       unsigned long page_size_mask,
+			       pgprot_t prot, bool init)
+{
+	bool pgd_changed;
+	unsigned long paddr_last;
+
+	paddr_last = phys_pgd_init(init_mm.pgd, paddr_start, paddr_end, page_size_mask,
+				   prot, init, &pgd_changed);
+	if (pgd_changed)
+		sync_global_pgds((unsigned long)__va(paddr_start),
+				 (unsigned long)__va(paddr_end) - 1);
+
+	return paddr_last;
+}
 
 /*
  * Create page table mapping for the physical memory for specific physical

-- 
2.50.1

Hi Brendan,

kernel test robot noticed the following build warnings:

[auto build test WARNING on bf2602a3cb2381fb1a04bf1c39a290518d2538d1]

url:    https://github.com/intel-lab-lkp/linux/commits/Brendan-Jackman/x86-mm-asi-Add-CONFIG_MITIGATION_ADDRESS_SPACE_ISOLATION/20250924-230633
base:   bf2602a3cb2381fb1a04bf1c39a290518d2538d1
patch link:    https://lore.kernel.org/r/20250924-b4-asi-page-alloc-v1-3-2d861768041f%40google.com
patch subject: [PATCH 03/21] x86/mm: factor out phys_pgd_init()
config: x86_64-kexec (https://download.01.org/0day-ci/archive/20250927/202509272136.N4ELb64u-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250927/202509272136.N4ELb64u-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202509272136.N4ELb64u-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> arch/x86/mm/init_64.c:747:23: warning: variable 'vaddr_start' set but not used [-Wunused-but-set-variable]
     747 |         unsigned long vaddr, vaddr_start, vaddr_end, vaddr_next, paddr_last;
         |                              ^
   1 warning generated.


vim +/vaddr_start +747 arch/x86/mm/init_64.c

7e82ea946ae4d0 arch/x86/mm/init_64.c Kirill A. Shutemov  2017-06-06  742  
eccd906484d1cd arch/x86/mm/init_64.c Brijesh Singh       2019-04-17  743  static unsigned long __meminit
46b7f8ebabd0a2 arch/x86/mm/init_64.c Brendan Jackman     2025-09-24  744  phys_pgd_init(pgd_t *pgd_page, unsigned long paddr_start, unsigned long paddr_end,
46b7f8ebabd0a2 arch/x86/mm/init_64.c Brendan Jackman     2025-09-24  745  	      unsigned long page_size_mask, pgprot_t prot, bool init, bool *pgd_changed)
^1da177e4c3f41 arch/x86_64/mm/init.c Linus Torvalds      2005-04-16  746  {
59b3d0206d74a7 arch/x86/mm/init_64.c Thomas Garnier      2016-06-21 @747  	unsigned long vaddr, vaddr_start, vaddr_end, vaddr_next, paddr_last;
^1da177e4c3f41 arch/x86_64/mm/init.c Linus Torvalds      2005-04-16  748  
46b7f8ebabd0a2 arch/x86/mm/init_64.c Brendan Jackman     2025-09-24  749  	*pgd_changed = false;
46b7f8ebabd0a2 arch/x86/mm/init_64.c Brendan Jackman     2025-09-24  750  
59b3d0206d74a7 arch/x86/mm/init_64.c Thomas Garnier      2016-06-21  751  	paddr_last = paddr_end;
59b3d0206d74a7 arch/x86/mm/init_64.c Thomas Garnier      2016-06-21  752  	vaddr = (unsigned long)__va(paddr_start);
59b3d0206d74a7 arch/x86/mm/init_64.c Thomas Garnier      2016-06-21  753  	vaddr_end = (unsigned long)__va(paddr_end);
59b3d0206d74a7 arch/x86/mm/init_64.c Thomas Garnier      2016-06-21  754  	vaddr_start = vaddr;
^1da177e4c3f41 arch/x86_64/mm/init.c Linus Torvalds      2005-04-16  755  
59b3d0206d74a7 arch/x86/mm/init_64.c Thomas Garnier      2016-06-21  756  	for (; vaddr < vaddr_end; vaddr = vaddr_next) {
46b7f8ebabd0a2 arch/x86/mm/init_64.c Brendan Jackman     2025-09-24  757  		pgd_t *pgd = pgd_offset_pgd(pgd_page, vaddr);
f2a6a7050109e0 arch/x86/mm/init_64.c Kirill A. Shutemov  2017-03-17  758  		p4d_t *p4d;
44df75e629106e arch/x86_64/mm/init.c Matt Tolentino      2006-01-17  759  
59b3d0206d74a7 arch/x86/mm/init_64.c Thomas Garnier      2016-06-21  760  		vaddr_next = (vaddr & PGDIR_MASK) + PGDIR_SIZE;
4f9c11dd49fb73 arch/x86/mm/init_64.c Jeremy Fitzhardinge 2008-06-25  761  
7e82ea946ae4d0 arch/x86/mm/init_64.c Kirill A. Shutemov  2017-06-06  762  		if (pgd_val(*pgd)) {
7e82ea946ae4d0 arch/x86/mm/init_64.c Kirill A. Shutemov  2017-06-06  763  			p4d = (p4d_t *)pgd_page_vaddr(*pgd);
7e82ea946ae4d0 arch/x86/mm/init_64.c Kirill A. Shutemov  2017-06-06  764  			paddr_last = phys_p4d_init(p4d, __pa(vaddr),
59b3d0206d74a7 arch/x86/mm/init_64.c Thomas Garnier      2016-06-21  765  						   __pa(vaddr_end),
eccd906484d1cd arch/x86/mm/init_64.c Brijesh Singh       2019-04-17  766  						   page_size_mask,
c164fbb40c43f8 arch/x86/mm/init_64.c Logan Gunthorpe     2020-04-10  767  						   prot, init);
4f9c11dd49fb73 arch/x86/mm/init_64.c Jeremy Fitzhardinge 2008-06-25  768  			continue;
4f9c11dd49fb73 arch/x86/mm/init_64.c Jeremy Fitzhardinge 2008-06-25  769  		}
4f9c11dd49fb73 arch/x86/mm/init_64.c Jeremy Fitzhardinge 2008-06-25  770  
7e82ea946ae4d0 arch/x86/mm/init_64.c Kirill A. Shutemov  2017-06-06  771  		p4d = alloc_low_page();
7e82ea946ae4d0 arch/x86/mm/init_64.c Kirill A. Shutemov  2017-06-06  772  		paddr_last = phys_p4d_init(p4d, __pa(vaddr), __pa(vaddr_end),
c164fbb40c43f8 arch/x86/mm/init_64.c Logan Gunthorpe     2020-04-10  773  					   page_size_mask, prot, init);
8ae3a5a8dff2c9 arch/x86/mm/init_64.c Jan Beulich         2008-08-21  774  
8ae3a5a8dff2c9 arch/x86/mm/init_64.c Jan Beulich         2008-08-21  775  		spin_lock(&init_mm.page_table_lock);
ed7588d5dc6f5e arch/x86/mm/init_64.c Kirill A. Shutemov  2018-05-18  776  		if (pgtable_l5_enabled())
eccd906484d1cd arch/x86/mm/init_64.c Brijesh Singh       2019-04-17  777  			pgd_populate_init(&init_mm, pgd, p4d, init);
7e82ea946ae4d0 arch/x86/mm/init_64.c Kirill A. Shutemov  2017-06-06  778  		else
eccd906484d1cd arch/x86/mm/init_64.c Brijesh Singh       2019-04-17  779  			p4d_populate_init(&init_mm, p4d_offset(pgd, vaddr),
eccd906484d1cd arch/x86/mm/init_64.c Brijesh Singh       2019-04-17  780  					  (pud_t *) p4d, init);
eccd906484d1cd arch/x86/mm/init_64.c Brijesh Singh       2019-04-17  781  
8ae3a5a8dff2c9 arch/x86/mm/init_64.c Jan Beulich         2008-08-21  782  		spin_unlock(&init_mm.page_table_lock);
46b7f8ebabd0a2 arch/x86/mm/init_64.c Brendan Jackman     2025-09-24  783  		*pgd_changed = true;
46b7f8ebabd0a2 arch/x86/mm/init_64.c Brendan Jackman     2025-09-24  784  	}
46b7f8ebabd0a2 arch/x86/mm/init_64.c Brendan Jackman     2025-09-24  785  
46b7f8ebabd0a2 arch/x86/mm/init_64.c Brendan Jackman     2025-09-24  786  	return paddr_last;
^1da177e4c3f41 arch/x86_64/mm/init.c Linus Torvalds      2005-04-16  787  }
9b861528a8012e arch/x86/mm/init_64.c Haicheng Li         2010-08-20  788  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

On Sat Sep 27, 2025 at 7:29 PM UTC, kernel test robot wrote:
> Hi Brendan,
>
> kernel test robot noticed the following build warnings:
>
> [auto build test WARNING on bf2602a3cb2381fb1a04bf1c39a290518d2538d1]

I've fixed this and the others in my WIP branch but I will wait a bit
longer before sending a v2..

They're all real issues - one of them confirms I have not exercised the
CMA with this code (by demonstrating that I did not even compile with
CONFIG_CMA=y). This one is just a benign bug that only shows up with
W=1.