xen64: map an initial chunk of physical memory
Early in boot, map a chunk of extra physical memory for use later on. We need a pool of mapped pages to allocate further pages to construct pagetables mapping all physical memory. 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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@ -1381,6 +1381,61 @@ static void convert_pfn_mfn(void *v)
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pte[i] = xen_make_pte(pte[i].pte);
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}
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/*
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* Identity map, in addition to plain kernel map. This needs to be
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* large enough to allocate page table pages to allocate the rest.
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* Each page can map 2MB.
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*/
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static pte_t level1_ident_pgt[PTRS_PER_PTE * 4] __page_aligned_bss;
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static __init void xen_map_identity_early(unsigned long max_pfn)
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{
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unsigned pmdidx, pteidx;
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unsigned ident_pte;
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unsigned long pfn;
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ident_pte = 0;
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pfn = 0;
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for(pmdidx = 0; pmdidx < PTRS_PER_PMD && pfn < max_pfn; pmdidx++) {
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pte_t *pte_page;
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BUG_ON(level2_ident_pgt[pmdidx].pmd != level2_kernel_pgt[pmdidx].pmd);
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/* Reuse or allocate a page of ptes */
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if (pmd_present(level2_ident_pgt[pmdidx]))
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pte_page = m2v(level2_ident_pgt[pmdidx].pmd);
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else {
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/* Check for free pte pages */
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if (ident_pte == ARRAY_SIZE(level1_ident_pgt))
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break;
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pte_page = &level1_ident_pgt[ident_pte];
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ident_pte += PTRS_PER_PTE;
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/* Install new l1 in l2(s) */
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level2_ident_pgt[pmdidx] = __pmd(__pa(pte_page) | _PAGE_TABLE);
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level2_kernel_pgt[pmdidx] = level2_ident_pgt[pmdidx];
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}
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/* Install mappings */
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for(pteidx = 0; pteidx < PTRS_PER_PTE; pteidx++, pfn++) {
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pte_t pte;
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if (pfn > max_pfn_mapped)
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max_pfn_mapped = pfn;
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if (!pte_none(pte_page[pteidx]))
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continue;
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pte = pfn_pte(pfn, PAGE_KERNEL_EXEC);
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pte_page[pteidx] = pte;
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}
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}
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for(pteidx = 0; pteidx < ident_pte; pteidx += PTRS_PER_PTE)
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set_page_prot(&level1_ident_pgt[pteidx], PAGE_KERNEL_RO);
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}
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/*
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* Set up the inital kernel pagetable.
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*
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@ -1392,7 +1447,7 @@ static void convert_pfn_mfn(void *v)
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* of the physical mapping once some sort of allocator has been set
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* up.
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*/
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static __init pgd_t *xen_setup_kernel_pagetable(pgd_t *pgd)
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static __init pgd_t *xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn)
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{
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pud_t *l3;
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pmd_t *l2;
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@ -1415,6 +1470,9 @@ static __init pgd_t *xen_setup_kernel_pagetable(pgd_t *pgd)
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l2 = m2v(l3[pud_index(__START_KERNEL_map + PMD_SIZE)].pud);
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memcpy(level2_fixmap_pgt, l2, sizeof(pmd_t) * PTRS_PER_PMD);
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/* Set up identity map */
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xen_map_identity_early(max_pfn);
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/* Make pagetable pieces RO */
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set_page_prot(init_level4_pgt, PAGE_KERNEL_RO);
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set_page_prot(level3_ident_pgt, PAGE_KERNEL_RO);
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@ -1424,7 +1482,7 @@ static __init pgd_t *xen_setup_kernel_pagetable(pgd_t *pgd)
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set_page_prot(level2_fixmap_pgt, PAGE_KERNEL_RO);
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/* Pin down new L4 */
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pin_pagetable_pfn(MMUEXT_PIN_L4_TABLE, PFN_DOWN(__pa(init_level4_pgt)));
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pin_pagetable_pfn(MMUEXT_PIN_L4_TABLE, PFN_DOWN(__pa_symbol(init_level4_pgt)));
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/* Unpin Xen-provided one */
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pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd)));
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@ -1433,19 +1491,23 @@ static __init pgd_t *xen_setup_kernel_pagetable(pgd_t *pgd)
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pgd = init_level4_pgt;
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xen_write_cr3(__pa(pgd));
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max_pfn_mapped = PFN_DOWN(__pa(pgd) +
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xen_start_info->nr_pt_frames*PAGE_SIZE +
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512*1024);
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reserve_early(__pa(xen_start_info->pt_base),
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__pa(xen_start_info->pt_base +
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xen_start_info->nr_pt_frames * PAGE_SIZE),
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"XEN PAGETABLES");
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return pgd;
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}
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#else
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static __init pgd_t *xen_setup_kernel_pagetable(pgd_t *pgd)
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static __init pgd_t *xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn)
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{
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init_pg_tables_start = __pa(pgd);
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init_pg_tables_end = __pa(pgd) + xen_start_info->nr_pt_frames*PAGE_SIZE;
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max_pfn_mapped = PFN_DOWN(init_pg_tables_end + 512*1024);
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x86_write_percpu(xen_cr3, __pa(pgd));
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x86_write_percpu(xen_current_cr3, __pa(pgd));
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return pgd;
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}
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#endif /* CONFIG_X86_64 */
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@ -1502,15 +1564,12 @@ asmlinkage void __init xen_start_kernel(void)
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per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0];
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xen_raw_console_write("mapping kernel into physical memory\n");
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pgd = xen_setup_kernel_pagetable(pgd);
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pgd = xen_setup_kernel_pagetable(pgd, xen_start_info->nr_pages);
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init_mm.pgd = pgd;
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/* keep using Xen gdt for now; no urgent need to change it */
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x86_write_percpu(xen_cr3, __pa(pgd));
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x86_write_percpu(xen_current_cr3, __pa(pgd));
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pv_info.kernel_rpl = 1;
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if (xen_feature(XENFEAT_supervisor_mode_kernel))
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pv_info.kernel_rpl = 0;
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