4.14-stable review patch. If anyone has any objections, please let me know.
------------------ From: Andy Lutomirski <[email protected]> commit f16b3da1dc936c0f8121741d0a1731bf242f2f56 upstream. I'm removing thread_struct::sp0, and Xen's usage of it is slightly dubious and unnecessary. Use appropriate helpers instead. While we're at at, reorder the code slightly to make it more obvious what's going on. Signed-off-by: Andy Lutomirski <[email protected]> Reviewed-by: Juergen Gross <[email protected]> Cc: Boris Ostrovsky <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Dave Hansen <[email protected]> Cc: Juergen Gross <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: http://lkml.kernel.org/r/d5b9a3da2b47c68325bd2bbe8f82d9554dee0d0f.1509609304.git.l...@kernel.org Signed-off-by: Ingo Molnar <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/x86/xen/smp_pv.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) --- a/arch/x86/xen/smp_pv.c +++ b/arch/x86/xen/smp_pv.c @@ -14,6 +14,7 @@ * single-threaded. */ #include <linux/sched.h> +#include <linux/sched/task_stack.h> #include <linux/err.h> #include <linux/slab.h> #include <linux/smp.h> @@ -294,12 +295,19 @@ cpu_initialize_context(unsigned int cpu, #endif memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt)); + /* + * Bring up the CPU in cpu_bringup_and_idle() with the stack + * pointing just below where pt_regs would be if it were a normal + * kernel entry. + */ ctxt->user_regs.eip = (unsigned long)cpu_bringup_and_idle; ctxt->flags = VGCF_IN_KERNEL; ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */ ctxt->user_regs.ds = __USER_DS; ctxt->user_regs.es = __USER_DS; ctxt->user_regs.ss = __KERNEL_DS; + ctxt->user_regs.cs = __KERNEL_CS; + ctxt->user_regs.esp = (unsigned long)task_pt_regs(idle); xen_copy_trap_info(ctxt->trap_ctxt); @@ -314,8 +322,13 @@ cpu_initialize_context(unsigned int cpu, ctxt->gdt_frames[0] = gdt_mfn; ctxt->gdt_ents = GDT_ENTRIES; + /* + * Set SS:SP that Xen will use when entering guest kernel mode + * from guest user mode. Subsequent calls to load_sp0() can + * change this value. + */ ctxt->kernel_ss = __KERNEL_DS; - ctxt->kernel_sp = idle->thread.sp0; + ctxt->kernel_sp = task_top_of_stack(idle); #ifdef CONFIG_X86_32 ctxt->event_callback_cs = __KERNEL_CS; @@ -327,10 +340,8 @@ cpu_initialize_context(unsigned int cpu, (unsigned long)xen_hypervisor_callback; ctxt->failsafe_callback_eip = (unsigned long)xen_failsafe_callback; - ctxt->user_regs.cs = __KERNEL_CS; per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir); - ctxt->user_regs.esp = idle->thread.sp0 - sizeof(struct pt_regs); ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_gfn(swapper_pg_dir)); if (HYPERVISOR_vcpu_op(VCPUOP_initialise, xen_vcpu_nr(cpu), ctxt)) BUG();
