[PATCHv2 4/4] x86/64/kexec: Rewrite init_transition_pgtable() with kernel_ident_mapping_init()

Kirill A. Shutemov
2024-08-14T12:46:22Z

init_transition_pgtable() sets up transitional page tables. Rewrite it
using kernel_ident_mapping_init() to avoid code duplication.

Change struct kimage_arch to track allocated page tables as a list, not
linking them to specific page table levels.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
arch/x86/include/asm/kexec.h | 5 +-
arch/x86/kernel/machine_kexec_64.c | 89 +++++++++++-------------------
2 files changed, 32 insertions(+), 62 deletions(-)

diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
index ae5482a2f0ca..7f9287f371e6 100644
--- a/arch/x86/include/asm/kexec.h
+++ b/arch/x86/include/asm/kexec.h
@@ -145,10 +145,7 @@ struct kimage_arch {
};
#else
struct kimage_arch {
- p4d_t *p4d;
- pud_t *pud;
- pmd_t *pmd;
- pte_t *pte;
+ struct list_head pages;
};
#endif /* CONFIG_X86_32 */

diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index 645690e81c2d..fb350372835c 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -134,71 +134,42 @@ map_efi_systab(struct x86_mapping_info *info, pgd_t *level4p)
return 0;
}

+static void *alloc_transition_pgt_page(void *data)
+{
+ struct kimage *image = (struct kimage *)data;
+ unsigned long virt;
+
+ virt = get_zeroed_page(GFP_KERNEL);
+ if (!virt)
+ return NULL;
+
+ list_add(&virt_to_page(virt)->lru, &image->arch.pages);
+ return (void *)virt;
+}
+
static void free_transition_pgtable(struct kimage *image)
{
- free_page((unsigned long)image->arch.p4d);
- image->arch.p4d = NULL;
- free_page((unsigned long)image->arch.pud);
- image->arch.pud = NULL;
- free_page((unsigned long)image->arch.pmd);
- image->arch.pmd = NULL;
- free_page((unsigned long)image->arch.pte);
- image->arch.pte = NULL;
+ struct page *page, *tmp;
+
+ list_for_each_entry_safe(page, tmp, &image->arch.pages, lru) {
+ list_del(&page->lru);
+ free_page((unsigned long)page_address(page));
+ }
}

static int init_transition_pgtable(struct kimage *image, pgd_t *pgd)
{
- pgprot_t prot = PAGE_KERNEL_EXEC_NOENC;
- unsigned long vaddr, paddr;
- int result = -ENOMEM;
- p4d_t *p4d;
- pud_t *pud;
- pmd_t *pmd;
- pte_t *pte;
+ struct x86_mapping_info info = {
+ .alloc_pgt_page = alloc_transition_pgt_page,
+ .context = image,
+ .page_flag = __PAGE_KERNEL_LARGE_EXEC,
+ .kernpg_flag = _KERNPG_TABLE_NOENC,
+ .offset = __START_KERNEL_map - phys_base,
+ };
+ unsigned long mstart = PAGE_ALIGN_DOWN(__pa(relocate_kernel));
+ unsigned long mend = mstart + PAGE_SIZE;

- vaddr = (unsigned long)relocate_kernel;
- paddr = __pa(relocate_kernel);
- pgd += pgd_index(vaddr);
- if (!pgd_present(*pgd)) {
- p4d = (p4d_t *)get_zeroed_page(GFP_KERNEL);
- if (!p4d)
- goto err;
- image->arch.p4d = p4d;
- set_pgd(pgd, __pgd(__pa(p4d) | _KERNPG_TABLE));
- }
- p4d = p4d_offset(pgd, vaddr);
- if (!p4d_present(*p4d)) {
- pud = (pud_t *)get_zeroed_page(GFP_KERNEL);
- if (!pud)
- goto err;
- image->arch.pud = pud;
- set_p4d(p4d, __p4d(__pa(pud) | _KERNPG_TABLE));
- }
- pud = pud_offset(p4d, vaddr);
- if (!pud_present(*pud)) {
- pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL);
- if (!pmd)
- goto err;
- image->arch.pmd = pmd;
- set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
- }
- pmd = pmd_offset(pud, vaddr);
- if (!pmd_present(*pmd)) {
- pte = (pte_t *)get_zeroed_page(GFP_KERNEL);
- if (!pte)
- goto err;
- image->arch.pte = pte;
- set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE));
- }
- pte = pte_offset_kernel(pmd, vaddr);
-
- if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
- prot = PAGE_KERNEL_EXEC;
-
- set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, prot));
- return 0;
-err:
- return result;
+ return kernel_ident_mapping_init(&info, pgd, mstart, mend);
}

static void *alloc_pgt_page(void *data)
@@ -299,6 +270,8 @@ int machine_kexec_prepare(struct kimage *image)
unsigned long start_pgtable;
int result;

+ INIT_LIST_HEAD(&image->arch.pages);
+
/* Calculate the offsets */
start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;

--
2.43.0