x86,xen: introduce x86_init.mapping.pagetable_reserve

Introduce a new x86_init hook called pagetable_reserve that during the
initial memory mapping is used to reserve a range of memory addresses for
kernel pagetable usage.

On native it just calls memblock_x86_reserve_range while on xen it also
takes care of setting the spare memory previously allocated
for kernel pagetable pages from RO to RW, so that it can be used for
other purposes.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index 7db7723d1f325f8016666806f790a015a4005c6b..d56187c6b8385425bb893f8d70003cb70290243a 100644 (file)
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -299,6 +299,7 @@ int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn,
 /* Install a pte for a particular vaddr in kernel space. */
 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_setup_start(pgd_t *base);
 extern void native_pagetable_setup_done(pgd_t *base);

diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
index 643ebf2e2ad8733ddbec5ca884ee21bf405c0226..d66b3a2207da6b99bdec216e840d7186cf8e4645 100644 (file)
--- a/arch/x86/include/asm/x86_init.h
+++ b/arch/x86/include/asm/x86_init.h
@@ -67,6 +67,14 @@ struct x86_init_oem {
        void (*banner)(void);
 };
 
+/**
+ * struct x86_init_mapping - platform specific initial kernel pagetable setup
+ * @pagetable_reserve: reserve a range of addresses for kernel pagetable usage
+ */
+struct x86_init_mapping {
+       void (*pagetable_reserve)(u64 start, u64 end);
+};
+
 /**
  * struct x86_init_paging - platform specific paging functions
  * @pagetable_setup_start:     platform specific pre paging_init() call
@@ -123,6 +131,7 @@ struct x86_init_ops {
        struct x86_init_mpparse         mpparse;
        struct x86_init_irqs            irqs;
        struct x86_init_oem             oem;
+       struct x86_init_mapping         mapping;
        struct x86_init_paging          paging;
        struct x86_init_timers          timers;
        struct x86_init_iommu           iommu;

diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
index c11514e9128b53cf0b6ad66d844c7703a6a8523a..75ef4b18e9b7963280c808bd59d1abe5579673ca 100644 (file)
--- a/arch/x86/kernel/x86_init.c
+++ b/arch/x86/kernel/x86_init.c
@@ -61,6 +61,10 @@ struct x86_init_ops x86_init __initdata = {
                .banner                 = default_banner,
        },
 
+       .mapping = {
+               .pagetable_reserve              = native_pagetable_reserve,
+       },
+
        .paging = {
                .pagetable_setup_start  = native_pagetable_setup_start,
                .pagetable_setup_done   = native_pagetable_setup_done,

diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 286d289b039b876ef046565d29552827d76f243c..ed0650bb1fcdfdf508dd17ee8d72023e2cde1148 100644 (file)
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -81,6 +81,11 @@ static void __init find_early_table_space(unsigned long end, int use_pse,
                end, pgt_buf_start << PAGE_SHIFT, pgt_buf_top << PAGE_SHIFT);
 }
 
+void native_pagetable_reserve(u64 start, u64 end)
+{
+       memblock_x86_reserve_range(start, end, "PGTABLE");
+}
+
 struct map_range {
        unsigned long start;
        unsigned long end;
@@ -273,8 +278,8 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
        __flush_tlb_all();
 
        if (!after_bootmem && pgt_buf_end > pgt_buf_start)
-               memblock_x86_reserve_range(pgt_buf_start << PAGE_SHIFT,
-                                pgt_buf_end << PAGE_SHIFT, "PGTABLE");
+               x86_init.mapping.pagetable_reserve(PFN_PHYS(pgt_buf_start),
+                               PFN_PHYS(pgt_buf_end));
 
        if (!after_bootmem)
                early_memtest(start, end);

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 6b833dba0d4694d987b68e606b2feb4581066c97..fec86809447f40f4303913b2c4c15e510bb75429 100644 (file)
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -1275,6 +1275,20 @@ static __init void xen_pagetable_setup_start(pgd_t *base)
 {
 }
 
+static __init void xen_mapping_pagetable_reserve(u64 start, u64 end)
+{
+       /* reserve the range used */
+       memblock_x86_reserve_range(start, end, "PGTABLE");
+
+       /* set as RW the rest */
+       printk(KERN_DEBUG "xen: setting RW the range %llx - %llx\n", end,
+                       PFN_PHYS(pgt_buf_top));
+       while (end < PFN_PHYS(pgt_buf_top)) {
+               make_lowmem_page_readwrite(__va(end));
+               end += PAGE_SIZE;
+       }
+}
+
 static void xen_post_allocator_init(void);
 
 static __init void xen_pagetable_setup_done(pgd_t *base)
@@ -2100,6 +2114,7 @@ static const struct pv_mmu_ops xen_mmu_ops __initdata = {
 
 void __init xen_init_mmu_ops(void)
 {
+       x86_init.mapping.pagetable_reserve = xen_mapping_pagetable_reserve;
        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;