diff options
Diffstat (limited to 'arch/x86/xen/setup.c')
| -rw-r--r-- | arch/x86/xen/setup.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c index e2d62d697b5d..8971a26d21ab 100644 --- a/arch/x86/xen/setup.c +++ b/arch/x86/xen/setup.c @@ -432,6 +432,24 @@ char * __init xen_memory_setup(void) * - mfn_list * - xen_start_info * See comment above "struct start_info" in <xen/interface/xen.h> + * We tried to make the the memblock_reserve more selective so + * that it would be clear what region is reserved. Sadly we ran + * in the problem wherein on a 64-bit hypervisor with a 32-bit + * initial domain, the pt_base has the cr3 value which is not + * neccessarily where the pagetable starts! As Jan put it: " + * Actually, the adjustment turns out to be correct: The page + * tables for a 32-on-64 dom0 get allocated in the order "first L1", + * "first L2", "first L3", so the offset to the page table base is + * indeed 2. When reading xen/include/public/xen.h's comment + * very strictly, this is not a violation (since there nothing is said + * that the first thing in the page table space is pointed to by + * pt_base; I admit that this seems to be implied though, namely + * do I think that it is implied that the page table space is the + * range [pt_base, pt_base + nt_pt_frames), whereas that + * range here indeed is [pt_base - 2, pt_base - 2 + nt_pt_frames), + * which - without a priori knowledge - the kernel would have + * difficulty to figure out)." - so lets just fall back to the + * easy way and reserve the whole region. */ memblock_reserve(__pa(xen_start_info->mfn_list), xen_start_info->pt_base - xen_start_info->mfn_list); |