4.19-stable review patch. If anyone has any objections, please let me know.
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From: Juergen Gross jgross@suse.com
commit 01bd2ac2f55a1916d81dace12fa8d7ae1c79b5ea upstream.
Commit f7c90c2aa40048 ("x86/xen: don't write ptes directly in 32-bit PV guests") introduced a regression for booting dom0 on huge systems with lots of RAM (in the TB range).
Reason is that on those hosts the p2m list needs to be moved early in the boot process and this requires temporary page tables to be created. Said commit modified xen_set_pte_init() to use a hypercall for writing a PTE, but this requires the page table being in the direct mapped area, which is not the case for the temporary page tables used in xen_relocate_p2m().
As the page tables are completely written before being linked to the actual address space instead of set_pte() a plain write to memory can be used in xen_relocate_p2m().
Fixes: f7c90c2aa40048 ("x86/xen: don't write ptes directly in 32-bit PV guests") Cc: stable@vger.kernel.org Signed-off-by: Juergen Gross jgross@suse.com Reviewed-by: Jan Beulich jbeulich@suse.com Signed-off-by: Juergen Gross jgross@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/xen/mmu_pv.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-)
--- a/arch/x86/xen/mmu_pv.c +++ b/arch/x86/xen/mmu_pv.c @@ -2106,10 +2106,10 @@ void __init xen_relocate_p2m(void) pt = early_memremap(pt_phys, PAGE_SIZE); clear_page(pt); for (idx_pte = 0; - idx_pte < min(n_pte, PTRS_PER_PTE); - idx_pte++) { - set_pte(pt + idx_pte, - pfn_pte(p2m_pfn, PAGE_KERNEL)); + idx_pte < min(n_pte, PTRS_PER_PTE); + idx_pte++) { + pt[idx_pte] = pfn_pte(p2m_pfn, + PAGE_KERNEL); p2m_pfn++; } n_pte -= PTRS_PER_PTE; @@ -2117,8 +2117,7 @@ void __init xen_relocate_p2m(void) make_lowmem_page_readonly(__va(pt_phys)); pin_pagetable_pfn(MMUEXT_PIN_L1_TABLE, PFN_DOWN(pt_phys)); - set_pmd(pmd + idx_pt, - __pmd(_PAGE_TABLE | pt_phys)); + pmd[idx_pt] = __pmd(_PAGE_TABLE | pt_phys); pt_phys += PAGE_SIZE; } n_pt -= PTRS_PER_PMD; @@ -2126,7 +2125,7 @@ void __init xen_relocate_p2m(void) make_lowmem_page_readonly(__va(pmd_phys)); pin_pagetable_pfn(MMUEXT_PIN_L2_TABLE, PFN_DOWN(pmd_phys)); - set_pud(pud + idx_pmd, __pud(_PAGE_TABLE | pmd_phys)); + pud[idx_pmd] = __pud(_PAGE_TABLE | pmd_phys); pmd_phys += PAGE_SIZE; } n_pmd -= PTRS_PER_PUD;