x86/xen: enable early use of set_fixmap in 32-bit Xen PV guest
Commit 7b25b9cb0dad83 ("x86/xen/time: Initialize pv xen time in
init_hypervisor_platform()") moved the mapping of the shared info area
before pagetable_init(). This breaks booting as 32-bit PV guest as the
use of set_fixmap isn't possible at this time on 32-bit.
This can be worked around by populating the needed PMD on 32-bit
kernel earlier.
In order not to reimplement populate_extra_pte() using extend_brk()
for allocating new page tables extend alloc_low_pages() to do that in
case the early page table pool is not yet available.
Fixes: 7b25b9cb0dad83 ("x86/xen/time: Initialize pv xen time in init_hypervisor_platform()")
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index acfab32..5c32a76 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -99,15 +99,22 @@
}
if ((pgt_buf_end + num) > pgt_buf_top || !can_use_brk_pgt) {
- unsigned long ret;
- if (min_pfn_mapped >= max_pfn_mapped)
- panic("alloc_low_pages: ran out of memory");
- ret = memblock_find_in_range(min_pfn_mapped << PAGE_SHIFT,
+ unsigned long ret = 0;
+
+ if (min_pfn_mapped < max_pfn_mapped) {
+ ret = memblock_find_in_range(
+ min_pfn_mapped << PAGE_SHIFT,
max_pfn_mapped << PAGE_SHIFT,
PAGE_SIZE * num , PAGE_SIZE);
+ }
+ if (ret)
+ memblock_reserve(ret, PAGE_SIZE * num);
+ else if (can_use_brk_pgt)
+ ret = __pa(extend_brk(PAGE_SIZE * num, PAGE_SIZE));
+
if (!ret)
panic("alloc_low_pages: can not alloc memory");
- memblock_reserve(ret, PAGE_SIZE * num);
+
pfn = ret >> PAGE_SHIFT;
} else {
pfn = pgt_buf_end;
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index a26a11d..52a7c3f 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -122,6 +122,8 @@
static void __init xen_pv_init_platform(void)
{
+ populate_extra_pte(fix_to_virt(FIX_PARAVIRT_BOOTMAP));
+
set_fixmap(FIX_PARAVIRT_BOOTMAP, xen_start_info->shared_info);
HYPERVISOR_shared_info = (void *)fix_to_virt(FIX_PARAVIRT_BOOTMAP);
diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
index 52206ad..9e70128 100644
--- a/arch/x86/xen/mmu_pv.c
+++ b/arch/x86/xen/mmu_pv.c
@@ -2171,6 +2171,8 @@
#else /* !CONFIG_X86_64 */
static RESERVE_BRK_ARRAY(pmd_t, initial_kernel_pmd, PTRS_PER_PMD);
static RESERVE_BRK_ARRAY(pmd_t, swapper_kernel_pmd, PTRS_PER_PMD);
+RESERVE_BRK(fixup_kernel_pmd, PAGE_SIZE);
+RESERVE_BRK(fixup_kernel_pte, PAGE_SIZE);
static void __init xen_write_cr3_init(unsigned long cr3)
{