When moving away RAM pages, there having been a mapping of those is not a proper indication that instead MMIO should be mapped there. At the point in time this effectively covers the low megabyte only. Mapping of that is, however, the job of init_mem_mapping(). Comparing the two one can also spot that we've been wrongly (or at least inconsistently) using PAGE_KERNEL_IO here.
Simply zap any such mappings instead. Signed-off-by: Jan Beulich <[email protected]> --- a/arch/x86/xen/setup.c +++ b/arch/x86/xen/setup.c @@ -425,13 +425,13 @@ static unsigned long __init xen_set_iden } /* - * If the PFNs are currently mapped, the VA mapping also needs - * to be updated to be 1:1. + * If the PFNs are currently mapped, their VA mappings need to be + * zapped. */ for (pfn = start_pfn; pfn <= max_pfn_mapped && pfn < end_pfn; pfn++) (void)HYPERVISOR_update_va_mapping( (unsigned long)__va(pfn << PAGE_SHIFT), - mfn_pte(pfn, PAGE_KERNEL_IO), 0); + native_make_pte(0), 0); return remap_pfn; }
