From 806c312e50f122c47913145cf884f53dd09d9199 Mon Sep 17 00:00:00 2001 From: Konrad Rzeszutek Wilk Date: Tue, 21 Aug 2012 14:31:24 -0400 Subject: [PATCH] xen/x86: Workaround 64-bit hypervisor and 32-bit initial domain. If a 64-bit hypervisor is booted with a 32-bit initial domain, the hypervisor deals with the initial domain as "compat" and does some extra adjustments (like pagetables are 4 bytes instead of 8). It also adjusts the xen_start_info->pt_base incorrectly. When booted with a 32-bit hypervisor (32-bit initial domain): .. (XEN) Start info: cf831000->cf83147c (XEN) Page tables: cf832000->cf8b5000 .. [ 0.000000] PT: cf832000 (f832000) [ 0.000000] Reserving PT: f832000->f8b5000 And with a 64-bit hypervisor: (XEN) Start info: 00000000cf831000->00000000cf8314b4 (XEN) Page tables: 00000000cf832000->00000000cf8b6000 [ 0.000000] PT: cf834000 (f834000) [ 0.000000] Reserving PT: f834000->f8b8000 To deal with this, we keep keep track of the highest physical address we have reserved via memblock_reserve. If that address does not overlap with pt_base, we have a gap which we reserve. Signed-off-by: Konrad Rzeszutek Wilk --- arch/x86/xen/enlighten.c | 30 +++++++++++++++++++++--------- 1 file changed, 21 insertions(+), 9 deletions(-) diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index e532eb50e8d7..511f92d79e4a 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -1002,19 +1002,24 @@ static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high) * If the MFN is not in the m2p (provided to us by the hypervisor) this * function won't do anything. In practice this means that the XenBus * MFN won't be available for the initial domain. */ -static void __init xen_reserve_mfn(unsigned long mfn) +static unsigned long __init xen_reserve_mfn(unsigned long mfn) { - unsigned long pfn; + unsigned long pfn, end_pfn = 0; if (!mfn) - return; + return end_pfn; + pfn = mfn_to_pfn(mfn); - if (phys_to_machine_mapping_valid(pfn)) - memblock_reserve(PFN_PHYS(pfn), PAGE_SIZE); + if (phys_to_machine_mapping_valid(pfn)) { + end_pfn = PFN_PHYS(pfn) + PAGE_SIZE; + memblock_reserve(PFN_PHYS(pfn), end_pfn); + } + return end_pfn; } static void __init xen_reserve_internals(void) { unsigned long size; + unsigned long last_phys = 0; if (!xen_pv_domain()) return; @@ -1022,12 +1027,13 @@ static void __init xen_reserve_internals(void) /* xen_start_info does not exist in the M2P, hence can't use * xen_reserve_mfn. */ memblock_reserve(__pa(xen_start_info), PAGE_SIZE); + last_phys = __pa(xen_start_info) + PAGE_SIZE; - xen_reserve_mfn(PFN_DOWN(xen_start_info->shared_info)); - xen_reserve_mfn(xen_start_info->store_mfn); + last_phys = max(xen_reserve_mfn(PFN_DOWN(xen_start_info->shared_info)), last_phys); + last_phys = max(xen_reserve_mfn(xen_start_info->store_mfn), last_phys); if (!xen_initial_domain()) - xen_reserve_mfn(xen_start_info->console.domU.mfn); + last_phys = max(xen_reserve_mfn(xen_start_info->console.domU.mfn), last_phys); if (xen_feature(XENFEAT_auto_translated_physmap)) return; @@ -1043,8 +1049,14 @@ static void __init xen_reserve_internals(void) * a lot (and call memblock_reserve for each PAGE), so lets just use * the easy way and reserve it wholesale. */ memblock_reserve(__pa(xen_start_info->mfn_list), size); - + last_phys = max(__pa(xen_start_info->mfn_list) + size, last_phys); /* The pagetables are reserved in mmu.c */ + + /* Under 64-bit hypervisor with a 32-bit domain, the hypervisor + * offsets the pt_base by two pages. Hence the reservation that is done + * in mmu.c misses two pages. We correct it here if we detect this. */ + if (last_phys < __pa(xen_start_info->pt_base)) + memblock_reserve(last_phys, __pa(xen_start_info->pt_base) - last_phys); } void xen_setup_shared_info(void) { -- 2.11.0