Messages in this thread Patch in this message |  | | Subject | Re: [patch V2 35/44] x86/idt: Switch early trap init to IDT tables | From | Boris Ostrovsky <> | Date | Fri, 25 Aug 2017 22:24:27 -0400 |
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On 08/25/2017 05:47 PM, Thomas Gleixner wrote: > > -/* Set of traps needed for early debugging. */ > -void __init early_trap_init(void) > -{ > - /* > - * Don't use IST to set DEBUG_STACK as it doesn't work until TSS > - * is ready in cpu_init() <-- trap_init(). Before trap_init(), > - * CPU runs at ring 0 so it is impossible to hit an invalid > - * stack. Using the original stack works well enough at this > - * early stage. DEBUG_STACK will be equipped after cpu_init() in > - * trap_init(). > - */ > - set_intr_gate(X86_TRAP_DB, debug); > - /* int3 can be called from all */ > - set_system_intr_gate(X86_TRAP_BP, &int3); > -#ifdef CONFIG_X86_32 > - set_intr_gate(X86_TRAP_PF, page_fault); > -#endif > - load_idt(&idt_descr);
This breaks 64-bit Xen PV guests: idt_setup_early_handler() is called from x86_64_start_kernel(), which is not executed on those guests.
The patch below fixes it.
-boris
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c index 03fb07d..ed0fb8a 100644 --- a/arch/x86/xen/enlighten_pv.c +++ b/arch/x86/xen/enlighten_pv.c @@ -1374,6 +1374,7 @@ asmlinkage __visible void __init xen_start_kernel(void) i386_start_kernel(); #else cr4_init_shadow(); /* 32b kernel does this in i386_start_kernel() */ + load_idt(&idt_descr); x86_64_start_reservations((char *)__pa_symbol(&boot_params)); #endif }
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