x86/mm: Fix guard hole handling
There is a guard hole at the beginning of the kernel address space, also used by hypervisors. It occupies 16 PGD entries. This reserved range is not defined explicitely, it is calculated relative to other entities: direct mapping and user space ranges. The calculation got broken by recent changes of the kernel memory layout: LDT remap range is now mapped before direct mapping and makes the calculation invalid. The breakage leads to crash on Xen dom0 boot[1]. Define the reserved range explicitely. It's part of kernel ABI (hypervisors expect it to be stable) and must not depend on changes in the rest of kernel memory layout. [1] https://lists.xenproject.org/archives/html/xen-devel/2018-11/msg03313.html Fixes: d52888aa ("x86/mm: Move LDT remap out of KASLR region on 5-level paging") Reported-by: NHans van Kranenburg <hans.van.kranenburg@mendix.com> Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Tested-by: NHans van Kranenburg <hans.van.kranenburg@mendix.com> Reviewed-by: NJuergen Gross <jgross@suse.com> Cc: bp@alien8.de Cc: hpa@zytor.com Cc: dave.hansen@linux.intel.com Cc: luto@kernel.org Cc: peterz@infradead.org Cc: boris.ostrovsky@oracle.com Cc: bhe@redhat.com Cc: linux-mm@kvack.org Cc: xen-devel@lists.xenproject.org Link: https://lkml.kernel.org/r/20181130202328.65359-2-kirill.shutemov@linux.intel.com
Showing
想要评论请 注册 或 登录