xen64: early mapping setup

Set up the initial pagetables to map the kernel mapping into the
physical mapping space.  This makes __va() usable, since it requires
physical mappings.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 176 insertions, 16 deletions

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 2b7bea3bb6f3..a991ee7ade9e 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -33,6 +33,7 @@
 #include <xen/interface/sched.h>
 #include <xen/features.h>
 #include <xen/page.h>
+#include <xen/hvc-console.h>
 
 #include <asm/paravirt.h>
 #include <asm/page.h>
@@ -1294,6 +1295,157 @@ static void __init xen_reserve_top(void)
 #endif  /* CONFIG_X86_32 */
 }
 
+#ifdef CONFIG_X86_64
+/*
+ * Like __va(), but returns address in the kernel mapping (which is
+ * all we have until the physical memory mapping has been set up.
+ */
+static void *__ka(phys_addr_t paddr)
+{
+        return (void *)(paddr + __START_KERNEL_map);
+}
+
+/* Convert a machine address to physical address */
+static unsigned long m2p(phys_addr_t maddr)
+{
+        phys_addr_t paddr;
+
+        maddr &= PTE_MASK;
+        paddr = mfn_to_pfn(maddr >> PAGE_SHIFT) << PAGE_SHIFT;
+
+        return paddr;
+}
+
+/* Convert a machine address to kernel virtual */
+static void *m2v(phys_addr_t maddr)
+{
+        return __ka(m2p(maddr));
+}
+
+static void walk(pgd_t *pgd, unsigned long addr)
+{
+        unsigned l4idx = pgd_index(addr);
+        unsigned l3idx = pud_index(addr);
+        unsigned l2idx = pmd_index(addr);
+        unsigned l1idx = pte_index(addr);
+        pgd_t l4;
+        pud_t l3;
+        pmd_t l2;
+        pte_t l1;
+
+        xen_raw_printk("walk %p, %lx -> %d %d %d %d\n",
+                       pgd, addr, l4idx, l3idx, l2idx, l1idx);
+
+        l4 = pgd[l4idx];
+        xen_raw_printk("  l4: %016lx\n", l4.pgd);
+        xen_raw_printk("      %016lx\n", pgd_val(l4));
+
+        l3 = ((pud_t *)(m2v(l4.pgd)))[l3idx];
+        xen_raw_printk("  l3: %016lx\n", l3.pud);
+        xen_raw_printk("      %016lx\n", pud_val(l3));
+
+        l2 = ((pmd_t *)(m2v(l3.pud)))[l2idx];
+        xen_raw_printk("  l2: %016lx\n", l2.pmd);
+        xen_raw_printk("      %016lx\n", pmd_val(l2));
+
+        l1 = ((pte_t *)(m2v(l2.pmd)))[l1idx];
+        xen_raw_printk("  l1: %016lx\n", l1.pte);
+        xen_raw_printk("      %016lx\n", pte_val(l1));
+}
+
+static void set_page_prot(void *addr, pgprot_t prot)
+{
+        unsigned long pfn = __pa(addr) >> PAGE_SHIFT;
+        pte_t pte = pfn_pte(pfn, prot);
+
+        xen_raw_printk("addr=%p pfn=%lx mfn=%lx prot=%016x pte=%016x\n",
+                       addr, pfn, get_phys_to_machine(pfn),
+                       pgprot_val(prot), pte.pte);
+
+        if (HYPERVISOR_update_va_mapping((unsigned long)addr, pte, 0))
+                BUG();
+}
+
+static void convert_pfn_mfn(void *v)
+{
+        pte_t *pte = v;
+        int i;
+
+        /* All levels are converted the same way, so just treat them
+           as ptes. */
+        for(i = 0; i < PTRS_PER_PTE; i++)
+                pte[i] = xen_make_pte(pte[i].pte);
+}
+
+/*
+ * Set up the inital kernel pagetable.
+ *
+ * We can construct this by grafting the Xen provided pagetable into
+ * head_64.S's preconstructed pagetables.  We copy the Xen L2's into
+ * level2_ident_pgt, level2_kernel_pgt and level2_fixmap_pgt.  This
+ * means that only the kernel has a physical mapping to start with -
+ * but that's enough to get __va working.  We need to fill in the rest
+ * of the physical mapping once some sort of allocator has been set
+ * up.
+ */
+static __init pgd_t *xen_setup_kernel_pagetable(pgd_t *pgd)
+{
+        pud_t *l3;
+        pmd_t *l2;
+
+        /* Zap identity mapping */
+        init_level4_pgt[0] = __pgd(0);
+
+        /* Pre-constructed entries are in pfn, so convert to mfn */
+        convert_pfn_mfn(init_level4_pgt);
+        convert_pfn_mfn(level3_ident_pgt);
+        convert_pfn_mfn(level3_kernel_pgt);
+
+        l3 = m2v(pgd[pgd_index(__START_KERNEL_map)].pgd);
+        l2 = m2v(l3[pud_index(__START_KERNEL_map)].pud);
+
+        memcpy(level2_ident_pgt, l2, sizeof(pmd_t) * PTRS_PER_PMD);
+        memcpy(level2_kernel_pgt, l2, sizeof(pmd_t) * PTRS_PER_PMD);
+
+        l3 = m2v(pgd[pgd_index(__START_KERNEL_map + PMD_SIZE)].pgd);
+        l2 = m2v(l3[pud_index(__START_KERNEL_map + PMD_SIZE)].pud);
+        memcpy(level2_fixmap_pgt, l2, sizeof(pmd_t) * PTRS_PER_PMD);
+
+        /* Make pagetable pieces RO */
+        set_page_prot(init_level4_pgt, PAGE_KERNEL_RO);
+        set_page_prot(level3_ident_pgt, PAGE_KERNEL_RO);
+        set_page_prot(level3_kernel_pgt, PAGE_KERNEL_RO);
+        set_page_prot(level2_ident_pgt, PAGE_KERNEL_RO);
+        set_page_prot(level2_kernel_pgt, PAGE_KERNEL_RO);
+        set_page_prot(level2_fixmap_pgt, PAGE_KERNEL_RO);
+
+        /* Pin down new L4 */
+        pin_pagetable_pfn(MMUEXT_PIN_L4_TABLE, PFN_DOWN(__pa(init_level4_pgt)));
+
+        /* Unpin Xen-provided one */
+        pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd)));
+
+        /* Switch over */
+        pgd = init_level4_pgt;
+        xen_write_cr3(__pa(pgd));
+
+        max_pfn_mapped = PFN_DOWN(__pa(pgd) +
+                                  xen_start_info->nr_pt_frames*PAGE_SIZE +
+                                  512*1024);
+
+        return pgd;
+}
+#else
+static __init pgd_t *xen_setup_kernel_pagetable(pgd_t *pgd)
+{
+        init_pg_tables_start = __pa(pgd);
+        init_pg_tables_end = __pa(pgd) + xen_start_info->nr_pt_frames*PAGE_SIZE;
+        max_pfn_mapped = PFN_DOWN(init_pg_tables_end + 512*1024);
+
+        return pgd;
+}
+#endif  /* CONFIG_X86_64 */
+
 /* First C function to be called on Xen boot */
 asmlinkage void __init xen_start_kernel(void)
 {
@@ -1336,32 +1488,29 @@ asmlinkage void __init xen_start_kernel(void)
 
         pgd = (pgd_t *)xen_start_info->pt_base;
 
-#ifdef CONFIG_X86_32
-        init_pg_tables_start = __pa(pgd);
-        init_pg_tables_end = __pa(pgd) + xen_start_info->nr_pt_frames*PAGE_SIZE;
-        max_pfn_mapped = (init_pg_tables_end + 512*1024) >> PAGE_SHIFT;
-#endif
+        /* Prevent unwanted bits from being set in PTEs. */
+        __supported_pte_mask &= ~_PAGE_GLOBAL;
+        if (!is_initial_xendomain())
+                __supported_pte_mask &= ~(_PAGE_PWT | _PAGE_PCD);
+
+        /* Don't do the full vcpu_info placement stuff until we have a
+           possible map and a non-dummy shared_info. */
+        per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0];
+
+        xen_raw_console_write("mapping kernel into physical memory\n");
+        pgd = xen_setup_kernel_pagetable(pgd);
 
-        init_mm.pgd = pgd; /* use the Xen pagetables to start */
+        init_mm.pgd = pgd;
 
         /* keep using Xen gdt for now; no urgent need to change it */
 
         x86_write_percpu(xen_cr3, __pa(pgd));
         x86_write_percpu(xen_current_cr3, __pa(pgd));
 
-        /* Don't do the full vcpu_info placement stuff until we have a
-           possible map and a non-dummy shared_info. */
-        per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0];
-
         pv_info.kernel_rpl = 1;
         if (xen_feature(XENFEAT_supervisor_mode_kernel))
                 pv_info.kernel_rpl = 0;
 
-        /* Prevent unwanted bits from being set in PTEs. */
-        __supported_pte_mask &= ~_PAGE_GLOBAL;
-        if (!is_initial_xendomain())
-                __supported_pte_mask &= ~(_PAGE_PWT | _PAGE_PCD);
-
         /* set the limit of our address space */
         xen_reserve_top();
 
@@ -1384,10 +1533,21 @@ asmlinkage void __init xen_start_kernel(void)
                 add_preferred_console("hvc", 0, NULL);
         }
 
+        xen_raw_console_write("about to get started...\n");
+
+#if 0
+        xen_raw_printk("&boot_params=%p __pa(&boot_params)=%lx __va(__pa(&boot_params))=%lx\n",
+                       &boot_params, __pa_symbol(&boot_params),
+                       __va(__pa_symbol(&boot_params)));
+
+        walk(pgd, &boot_params);
+        walk(pgd, __va(__pa(&boot_params)));
+#endif
+
         /* Start the world */
 #ifdef CONFIG_X86_32
         i386_start_kernel();
 #else
-        x86_64_start_kernel((char *)&boot_params);
+        x86_64_start_reservations((char *)__pa_symbol(&boot_params));
 #endif
 }