[Xen-devel] [PATCH 3/5] X86/XEN: Introduce the x86_init.paging.pagetable_init PVOPS

[Attilio Rao <attilio.rao@xxxxxxxxxx>]

This new PVOPS is responsible to setup the kernel pagetables and
replace entirely x86_init.paging.pagetable_setup_start and
x86_init.paging.pagetable_setup_done PVOPS work.

For performance the x86_64 stub is implemented as a macro to paging_init()
rather than an actual function stub.

Signed-off-by: Attilio Rao <attilio.rao@xxxxxxxxxx>
---
 arch/x86/include/asm/pgtable_types.h |    2 +
 arch/x86/include/asm/x86_init.h      |    2 +
 arch/x86/kernel/x86_init.c           |    1 +
 arch/x86/mm/init_32.c                |   35 ++++++++++++++++++++++++++++++++++
 arch/x86/xen/mmu.c                   |   12 +++++++++-
 5 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/pgtable_types.h 
b/arch/x86/include/asm/pgtable_types.h
index 9b1c1f7..55f24b5 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -303,9 +303,11 @@ void set_pte_vaddr(unsigned long vaddr, pte_t pte);
 
 extern void native_pagetable_reserve(u64 start, u64 end);
 #ifdef CONFIG_X86_32
+extern void native_pagetable_init(void);
 extern void native_pagetable_setup_start(void);
 extern void native_pagetable_setup_done(void);
 #else
+#define native_pagetable_init        paging_init
 #define native_pagetable_setup_start x86_init_pgd_noop
 #define native_pagetable_setup_done  x86_init_pgd_noop
 #endif
diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
index efd0075..a74cc19 100644
--- a/arch/x86/include/asm/x86_init.h
+++ b/arch/x86/include/asm/x86_init.h
@@ -81,10 +81,12 @@ struct x86_init_mapping {
 
 /**
  * struct x86_init_paging - platform specific paging functions
+ * @pagetable_init:            platform specific paging initialization call
  * @pagetable_setup_start:     platform specific pre paging_init() call
  * @pagetable_setup_done:      platform specific post paging_init() call
  */
 struct x86_init_paging {
+       void (*pagetable_init)(void);
        void (*pagetable_setup_start)(void);
        void (*pagetable_setup_done)(void);
 };
diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
index 849be14..c1e910a 100644
--- a/arch/x86/kernel/x86_init.c
+++ b/arch/x86/kernel/x86_init.c
@@ -68,6 +68,7 @@ struct x86_init_ops x86_init __initdata = {
        },
 
        .paging = {
+               .pagetable_init         = native_pagetable_init,
                .pagetable_setup_start  = native_pagetable_setup_start,
                .pagetable_setup_done   = native_pagetable_setup_done,
        },
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 7999cef..2ff4790 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -445,6 +445,41 @@ static inline void permanent_kmaps_init(pgd_t *pgd_base)
 }
 #endif /* CONFIG_HIGHMEM */
 
+void __init native_pagetable_init(void)
+{
+       unsigned long pfn, va;
+       pgd_t *base;
+       pgd_t *pgd;
+       pud_t *pud;
+       pmd_t *pmd;
+       pte_t *pte;
+
+       base = swapper_pg_dir;
+
+       /*
+        * Remove any mappings which extend past the end of physical
+        * memory from the boot time page table:
+        */
+       for (pfn = max_low_pfn + 1; pfn < 1<<(32-PAGE_SHIFT); pfn++) {
+               va = PAGE_OFFSET + (pfn<<PAGE_SHIFT);
+               pgd = base + pgd_index(va);
+               if (!pgd_present(*pgd))
+                       break;
+
+               pud = pud_offset(pgd, va);
+               pmd = pmd_offset(pud, va);
+               if (!pmd_present(*pmd))
+                       break;
+
+               pte = pte_offset_kernel(pmd, va);
+               if (!pte_present(*pte))
+                       break;
+
+               pte_clear(NULL, va, pte);
+       }
+       paravirt_alloc_pmd(&init_mm, __pa(base) >> PAGE_SHIFT);
+       paging_init();
+}
 void __init native_pagetable_setup_start(void)
 {
        unsigned long pfn, va;
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 04a0a8f..68466ce 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -1174,6 +1174,15 @@ static void xen_exit_mmap(struct mm_struct *mm)
        spin_unlock(&mm->page_table_lock);
 }
 
+static void xen_post_allocator_init(void);
+
+static void __init xen_pagetable_init(void)
+{
+       paging_init();
+       xen_setup_shared_info();
+       xen_post_allocator_init();
+}
+
 static void __init xen_pagetable_setup_start(void)
 {
 }
@@ -1192,8 +1201,6 @@ static __init void xen_mapping_pagetable_reserve(u64 
start, u64 end)
        }
 }
 
-static void xen_post_allocator_init(void);
-
 static void __init xen_pagetable_setup_done(void)
 {
        xen_setup_shared_info();
@@ -2068,6 +2075,7 @@ static const struct pv_mmu_ops xen_mmu_ops __initconst = {
 void __init xen_init_mmu_ops(void)
 {
        x86_init.mapping.pagetable_reserve = xen_mapping_pagetable_reserve;
+       x86_init.paging.pagetable_init = xen_pagetable_init;
        x86_init.paging.pagetable_setup_start = xen_pagetable_setup_start;
        x86_init.paging.pagetable_setup_done = xen_pagetable_setup_done;
        pv_mmu_ops = xen_mmu_ops;
-- 
1.7.2.5


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