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Subject[PATCH 31 of 55] xen32: create initial mappings like 64-bit
Date
From
Rearrange the pagetable initialization to share code with the 64-bit
kernel. Rather than deferring anything to pagetable_setup_start, just
set up an initial pagetable in swapper_pg_dir early at startup, and
create an additional 8MB of physical memory mappings. This matches
the native head_32.S mappings to a large degree, and allows the rest
of the pagetable setup to continue without much Xen vs. native
difference.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
arch/x86/xen/enlighten.c | 130 ++++++++++++++++++----------------------------
1 file changed, 52 insertions(+), 78 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
@@ -854,50 +854,6 @@

static __init void xen_pagetable_setup_start(pgd_t *base)
{
-#ifdef CONFIG_X86_32
- pgd_t *xen_pgd = (pgd_t *)xen_start_info->pt_base;
- int i;
-
- init_mm.pgd = base;
- /*
- * copy top-level of Xen-supplied pagetable into place. This
- * is a stand-in while we copy the pmd pages.
- */
- memcpy(base, xen_pgd, PTRS_PER_PGD * sizeof(pgd_t));
-
- /*
- * For PAE, need to allocate new pmds, rather than
- * share Xen's, since Xen doesn't like pmd's being
- * shared between address spaces.
- */
- for (i = 0; i < PTRS_PER_PGD; i++) {
- if (pgd_val_ma(xen_pgd[i]) & _PAGE_PRESENT) {
- pmd_t *pmd = (pmd_t *)alloc_bootmem_low_pages(PAGE_SIZE);
-
- memcpy(pmd, (void *)pgd_page_vaddr(xen_pgd[i]),
- PAGE_SIZE);
-
- make_lowmem_page_readonly(pmd);
-
- set_pgd(&base[i], __pgd(1 + __pa(pmd)));
- } else
- pgd_clear(&base[i]);
- }
-
- /* make sure zero_page is mapped RO so we can use it in pagetables */
- make_lowmem_page_readonly(empty_zero_page);
- make_lowmem_page_readonly(base);
- /*
- * Switch to new pagetable. This is done before
- * pagetable_init has done anything so that the new pages
- * added to the table can be prepared properly for Xen.
- */
- xen_write_cr3(__pa(base));
-
- /* Unpin initial Xen pagetable */
- pin_pagetable_pfn(MMUEXT_UNPIN_TABLE,
- PFN_DOWN(__pa(xen_start_info->pt_base)));
-#endif /* CONFIG_X86_32 */
}

void xen_setup_shared_info(void)
@@ -936,12 +892,6 @@
pv_mmu_ops.set_pte = xen_set_pte;

xen_setup_shared_info();
-
-#ifdef CONFIG_X86_32
- /* Actually pin the pagetable down, but we can't set PG_pinned
- yet because the page structures don't exist yet. */
- pin_pagetable_pfn(MMUEXT_PIN_L3_TABLE, PFN_DOWN(__pa(base)));
-#endif
}

static __init void xen_post_allocator_init(void)
@@ -1299,14 +1249,17 @@
#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)
{
+#ifdef CONFIG_X86_64
return (void *)(paddr + __START_KERNEL_map);
+#else
+ return __va(paddr);
+#endif
}

/* Convert a machine address to physical address */
@@ -1326,6 +1279,7 @@
return __ka(m2p(maddr));
}

+#ifdef CONFIG_X86_64
static void walk(pgd_t *pgd, unsigned long addr)
{
unsigned l4idx = pgd_index(addr);
@@ -1356,29 +1310,19 @@
xen_raw_printk(" l1: %016lx\n", l1.pte);
xen_raw_printk(" %016lx\n", pte_val(l1));
}
+#endif

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",
+ xen_raw_printk("addr=%p pfn=%lx mfn=%lx prot=%016llx pte=%016llx\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);
}

/*
@@ -1388,7 +1332,7 @@
*/
static pte_t level1_ident_pgt[PTRS_PER_PTE * 4] __page_aligned_bss;

-static __init void xen_map_identity_early(unsigned long max_pfn)
+static __init void xen_map_identity_early(pmd_t *pmd, unsigned long max_pfn)
{
unsigned pmdidx, pteidx;
unsigned ident_pte;
@@ -1399,11 +1343,9 @@
for(pmdidx = 0; pmdidx < PTRS_PER_PMD && pfn < max_pfn; pmdidx++) {
pte_t *pte_page;

- BUG_ON(level2_ident_pgt[pmdidx].pmd != level2_kernel_pgt[pmdidx].pmd);
-
/* Reuse or allocate a page of ptes */
- if (pmd_present(level2_ident_pgt[pmdidx]))
- pte_page = m2v(level2_ident_pgt[pmdidx].pmd);
+ if (pmd_present(pmd[pmdidx]))
+ pte_page = m2v(pmd[pmdidx].pmd);
else {
/* Check for free pte pages */
if (ident_pte == ARRAY_SIZE(level1_ident_pgt))
@@ -1412,9 +1354,7 @@
pte_page = &level1_ident_pgt[ident_pte];
ident_pte += PTRS_PER_PTE;

- /* Install new l1 in l2(s) */
- level2_ident_pgt[pmdidx] = __pmd(__pa(pte_page) | _PAGE_TABLE);
- level2_kernel_pgt[pmdidx] = level2_ident_pgt[pmdidx];
+ pmd[pmdidx] = __pmd(__pa(pte_page) | _PAGE_TABLE);
}

/* Install mappings */
@@ -1434,6 +1374,20 @@

for(pteidx = 0; pteidx < ident_pte; pteidx += PTRS_PER_PTE)
set_page_prot(&level1_ident_pgt[pteidx], PAGE_KERNEL_RO);
+
+ set_page_prot(pmd, PAGE_KERNEL_RO);
+}
+
+#ifdef CONFIG_X86_64
+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);
}

/*
@@ -1471,18 +1425,18 @@
memcpy(level2_fixmap_pgt, l2, sizeof(pmd_t) * PTRS_PER_PMD);

/* Set up identity map */
- xen_map_identity_early(max_pfn);
+ xen_map_identity_early(level2_ident_pgt, max_pfn);

/* 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_symbol(init_level4_pgt)));
+ pin_pagetable_pfn(MMUEXT_PIN_L4_TABLE,
+ PFN_DOWN(__pa_symbol(init_level4_pgt)));

/* Unpin Xen-provided one */
pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd)));
@@ -1498,17 +1452,37 @@

return pgd;
}
-#else
+#else /* !CONFIG_X86_64 */
+static pmd_t level2_kernel_pgt[PTRS_PER_PMD] __page_aligned_bss;
+
static __init pgd_t *xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn)
{
+ pmd_t *kernel_pmd;
+
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);

- x86_write_percpu(xen_cr3, __pa(pgd));
- x86_write_percpu(xen_current_cr3, __pa(pgd));
+ kernel_pmd = m2v(pgd[KERNEL_PGD_BOUNDARY].pgd);
+ memcpy(level2_kernel_pgt, kernel_pmd, sizeof(pmd_t) * PTRS_PER_PMD);

- return pgd;
+ xen_map_identity_early(level2_kernel_pgt, max_pfn);
+
+ memcpy(swapper_pg_dir, pgd, sizeof(pgd_t) * PTRS_PER_PGD);
+ set_pgd(&swapper_pg_dir[KERNEL_PGD_BOUNDARY],
+ __pgd(__pa(level2_kernel_pgt) | _PAGE_PRESENT));
+
+ set_page_prot(level2_kernel_pgt, PAGE_KERNEL_RO);
+ set_page_prot(swapper_pg_dir, PAGE_KERNEL_RO);
+ set_page_prot(empty_zero_page, PAGE_KERNEL_RO);
+
+ pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd)));
+
+ xen_write_cr3(__pa(swapper_pg_dir));
+
+ pin_pagetable_pfn(MMUEXT_PIN_L3_TABLE, PFN_DOWN(__pa(swapper_pg_dir)));
+
+ return swapper_pg_dir;
}
#endif /* CONFIG_X86_64 */




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