From 4f803c39abc21f298fd8b5e405999d45f3107a6b Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Wed, 10 May 2017 06:08:44 +0200 Subject: [PATCH] xen: adjust early dom0 p2m handling to xen hypervisor behavior When booted as pv-guest the p2m list presented by the Xen is already mapped to virtual addresses. In dom0 case the hypervisor might make use of 2M- or 1G-pages for this mapping. Unfortunately while being properly aligned in virtual and machine address space, those pages might not be aligned properly in guest physical address space. So when trying to obtain the guest physical address of such a page pud_pfn() and pmd_pfn() must be avoided as those will mask away guest physical address bits not being zero in this special case. Signed-off-by: Juergen Gross Reviewed-by: Jan Beulich Signed-off-by: Juergen Gross --- arch/x86/xen/mmu_pv.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c index 9d9ae6650aa1d..7397d8b8459d6 100644 --- a/arch/x86/xen/mmu_pv.c +++ b/arch/x86/xen/mmu_pv.c @@ -2025,7 +2025,8 @@ static unsigned long __init xen_read_phys_ulong(phys_addr_t addr) /* * Translate a virtual address to a physical one without relying on mapped - * page tables. + * page tables. Don't rely on big pages being aligned in (guest) physical + * space! */ static phys_addr_t __init xen_early_virt_to_phys(unsigned long vaddr) { @@ -2046,7 +2047,7 @@ static phys_addr_t __init xen_early_virt_to_phys(unsigned long vaddr) sizeof(pud))); if (!pud_present(pud)) return 0; - pa = pud_pfn(pud) << PAGE_SHIFT; + pa = pud_val(pud) & PTE_PFN_MASK; if (pud_large(pud)) return pa + (vaddr & ~PUD_MASK); @@ -2054,7 +2055,7 @@ static phys_addr_t __init xen_early_virt_to_phys(unsigned long vaddr) sizeof(pmd))); if (!pmd_present(pmd)) return 0; - pa = pmd_pfn(pmd) << PAGE_SHIFT; + pa = pmd_val(pmd) & PTE_PFN_MASK; if (pmd_large(pmd)) return pa + (vaddr & ~PMD_MASK); -- 2.39.5