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Subject[PATCH 28 of 55] xen64: early mapping setup
Date
From
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>
---
arch/x86/xen/enlighten.c | 192 ++++++++++++++++++++++++++++++++++++++----
include/asm-x86/pgtable_64.h | 2
2 files changed, 178 insertions(+), 16 deletions(-)
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
--- 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 @@
#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)
{
@@ -1336,31 +1488,28 @@

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);

- init_mm.pgd = pgd; /* use the Xen pagetables to start */
+ /* 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;

/* 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 @@
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
}
diff --git a/include/asm-x86/pgtable_64.h b/include/asm-x86/pgtable_64.h
--- a/include/asm-x86/pgtable_64.h
+++ b/include/asm-x86/pgtable_64.h
@@ -16,6 +16,8 @@
extern pud_t level3_kernel_pgt[512];
extern pud_t level3_ident_pgt[512];
extern pmd_t level2_kernel_pgt[512];
+extern pmd_t level2_fixmap_pgt[512];
+extern pmd_t level2_ident_pgt[512];
extern pgd_t init_level4_pgt[];

#define swapper_pg_dir init_level4_pgt



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