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xen64: early mapping setup
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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>
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Jeremy Fitzhardinge authored and Ingo Molnar committed Jul 16, 2008
1 parent 3d75e1b commit 084a2a4
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Showing 2 changed files with 178 additions and 16 deletions.
192 changes: 176 additions & 16 deletions arch/x86/xen/enlighten.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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>
Expand Down Expand Up @@ -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)
{
Expand Down Expand Up @@ -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();

Expand All @@ -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
}
2 changes: 2 additions & 0 deletions include/asm-x86/pgtable_64.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down

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