x86/acpi: Replace manual page table initialization with kernel_ident_mapping_init()

The init_transition_pgtable() functions maps the page with
asm_acpi_mp_play_dead() into an identity mapping.

Replace open-coded manual page table initialization with
kernel_ident_mapping_init() to avoid code duplication.

Use x86_mapping_info::offset to get the page mapped at the
correct location.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20241016111458.846228-3-kirill.shutemov@linux.intel.com

diff --git a/arch/x86/kernel/acpi/madt_wakeup.c b/arch/x86/kernel/acpi/madt_wakeup.c
index d5ef6215583bcf734627058bf9b46dd2b936508f..f36f28405dcc63abfef5ee089022c4ef159907d9 100644 (file)
--- a/arch/x86/kernel/acpi/madt_wakeup.c
+++ b/arch/x86/kernel/acpi/madt_wakeup.c
@@ -70,58 +70,6 @@ static void __init free_pgt_page(void *pgt, void *dummy)
        return memblock_free(pgt, PAGE_SIZE);
 }
 
-/*
- * Make sure asm_acpi_mp_play_dead() is present in the identity mapping at
- * the same place as in the kernel page tables. asm_acpi_mp_play_dead() switches
- * to the identity mapping and the function has be present at the same spot in
- * the virtual address space before and after switching page tables.
- */
-static int __init init_transition_pgtable(pgd_t *pgd)
-{
-       pgprot_t prot = PAGE_KERNEL_EXEC_NOENC;
-       unsigned long vaddr, paddr;
-       p4d_t *p4d;
-       pud_t *pud;
-       pmd_t *pmd;
-       pte_t *pte;
-
-       vaddr = (unsigned long)asm_acpi_mp_play_dead;
-       pgd += pgd_index(vaddr);
-       if (!pgd_present(*pgd)) {
-               p4d = (p4d_t *)alloc_pgt_page(NULL);
-               if (!p4d)
-                       return -ENOMEM;
-               set_pgd(pgd, __pgd(__pa(p4d) | _KERNPG_TABLE));
-       }
-       p4d = p4d_offset(pgd, vaddr);
-       if (!p4d_present(*p4d)) {
-               pud = (pud_t *)alloc_pgt_page(NULL);
-               if (!pud)
-                       return -ENOMEM;
-               set_p4d(p4d, __p4d(__pa(pud) | _KERNPG_TABLE));
-       }
-       pud = pud_offset(p4d, vaddr);
-       if (!pud_present(*pud)) {
-               pmd = (pmd_t *)alloc_pgt_page(NULL);
-               if (!pmd)
-                       return -ENOMEM;
-               set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
-       }
-       pmd = pmd_offset(pud, vaddr);
-       if (!pmd_present(*pmd)) {
-               pte = (pte_t *)alloc_pgt_page(NULL);
-               if (!pte)
-                       return -ENOMEM;
-               set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE));
-       }
-       pte = pte_offset_kernel(pmd, vaddr);
-
-       paddr = __pa(vaddr);
-       set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, prot));
-
-       return 0;
-}
-
 static int __init acpi_mp_setup_reset(u64 reset_vector)
 {
        struct x86_mapping_info info = {
@@ -130,6 +78,7 @@ static int __init acpi_mp_setup_reset(u64 reset_vector)
                .page_flag      = __PAGE_KERNEL_LARGE_EXEC,
                .kernpg_flag    = _KERNPG_TABLE_NOENC,
        };
+       unsigned long mstart, mend;
        pgd_t *pgd;
 
        pgd = alloc_pgt_page(NULL);
@@ -137,8 +86,6 @@ static int __init acpi_mp_setup_reset(u64 reset_vector)
                return -ENOMEM;
 
        for (int i = 0; i < nr_pfn_mapped; i++) {
-               unsigned long mstart, mend;
-
                mstart = pfn_mapped[i].start << PAGE_SHIFT;
                mend   = pfn_mapped[i].end << PAGE_SHIFT;
                if (kernel_ident_mapping_init(&info, pgd, mstart, mend)) {
@@ -147,14 +94,24 @@ static int __init acpi_mp_setup_reset(u64 reset_vector)
                }
        }
 
-       if (kernel_ident_mapping_init(&info, pgd,
-                                     PAGE_ALIGN_DOWN(reset_vector),
-                                     PAGE_ALIGN(reset_vector + 1))) {
+       mstart = PAGE_ALIGN_DOWN(reset_vector);
+       mend = mstart + PAGE_SIZE;
+       if (kernel_ident_mapping_init(&info, pgd, mstart, mend)) {
                kernel_ident_mapping_free(&info, pgd);
                return -ENOMEM;
        }
 
-       if (init_transition_pgtable(pgd)) {
+       /*
+        * Make sure asm_acpi_mp_play_dead() is present in the identity mapping
+        * at the same place as in the kernel page tables.
+        * asm_acpi_mp_play_dead() switches to the identity mapping and the
+        * function must be present at the same spot in the virtual address space
+        * before and after switching page tables.
+        */
+       info.offset = __START_KERNEL_map - phys_base;
+       mstart = PAGE_ALIGN_DOWN(__pa(asm_acpi_mp_play_dead));
+       mend = mstart + PAGE_SIZE;
+       if (kernel_ident_mapping_init(&info, pgd, mstart, mend)) {
                kernel_ident_mapping_free(&info, pgd);
                return -ENOMEM;
        }