Re: linux-next: manual merge of the xen-tip tree with the tip tree

Juergen Gross
2017-08-31T10:11:57Z

On 31/08/17 11:00, Thomas Gleixner wrote:
> On Thu, 31 Aug 2017, Thomas Gleixner wrote:
>> Hrm. For some reason I missed to remove these defines after getting rid of
>> the tracing idt.
>>
>> I'll remove that now in tip and pull in the XEN stuff to see what needs to
>> be done.
>
> I pushed out the removal of the trace leftovers. Talked to Juergen on IRC
> and he suggested to revert the XEN patch in the xen tree and merge it
> through tip.
>
> I've applied it on top of tip:x86/apic and fixed up the merge conflicts
> mindlessly. Patch below.
>
> Juergen, can you please check the result?
>
> Thanks,
>
> tglx
>
> 8<-------------
> Subject: xen: Get rid of paravirt op adjust_exception_frame
> From: Juergen Gross <jgross@suse.com>
> Date: Fri, 11 Aug 2017 16:54:48 +0200
>
> When running as Xen pv-guest the exception frame on the stack contains
> %r11 and %rcx additional to the other data pushed by the processor.
>
> Instead of having a paravirt op being called for each exception type
> prepend the Xen specific code to each exception entry. When running as
> Xen pv-guest just use the exception entry with prepended instructions,
> otherwise use the entry without the Xen specific code.
>
> Signed-off-by: Juergen Gross <jgross@suse.com>
> Cc: xen-devel@lists.xenproject.org
> Cc: boris.ostrovsky@oracle.com
> Cc: luto@amacapital.net
> Link: http://lkml.kernel.org/r/20170811145448.5679-1-jgross@suse.com
>
> ---
> arch/x86/entry/entry_64.S | 11 +--
> arch/x86/entry/entry_64_compat.S | 1
> arch/x86/include/asm/paravirt.h | 5 -
> arch/x86/include/asm/paravirt_types.h | 4 -
> arch/x86/include/asm/proto.h | 3 +
> arch/x86/include/asm/traps.h | 3 -
> arch/x86/kernel/asm-offsets_64.c | 1
> arch/x86/kernel/paravirt.c | 3 -
> arch/x86/xen/enlighten_pv.c | 96 ++++++++++++++++++++++------------
> arch/x86/xen/irq.c | 3 -
> arch/x86/xen/xen-ops.h | 1
> 11 files changed, 70 insertions(+), 61 deletions(-)
>
> --- a/arch/x86/entry/entry_64.S
> +++ b/arch/x86/entry/entry_64.S
> @@ -816,7 +816,6 @@ ENTRY(\sym)
> .endif
>
> ASM_CLAC
> - PARAVIRT_ADJUST_EXCEPTION_FRAME
>
> .ifeq \has_error_code
> pushq $-1 /* ORIG_RAX: no syscall to restart */
> @@ -962,7 +961,7 @@ ENTRY(do_softirq_own_stack)
> ENDPROC(do_softirq_own_stack)
>
> #ifdef CONFIG_XEN
> -idtentry xen_hypervisor_callback xen_do_hypervisor_callback has_error_code=0
> +idtentry hypervisor_callback xen_do_hypervisor_callback has_error_code=0
>
> /*
> * A note on the "critical region" in our callback handler.
> @@ -1029,8 +1028,6 @@ ENTRY(xen_failsafe_callback)
> movq 8(%rsp), %r11
> addq $0x30, %rsp
> pushq $0 /* RIP */
> - pushq %r11
> - pushq %rcx
> UNWIND_HINT_IRET_REGS offset=8
> jmp general_protection
> 1: /* Segment mismatch => Category 1 (Bad segment). Retry the IRET. */
> @@ -1061,9 +1058,8 @@ idtentry int3 do_int3 has_error_code
> idtentry stack_segment do_stack_segment has_error_code=1
>
> #ifdef CONFIG_XEN
> -idtentry xen_debug do_debug has_error_code=0
> -idtentry xen_int3 do_int3 has_error_code=0
> -idtentry xen_stack_segment do_stack_segment has_error_code=1
> +idtentry xendebug do_debug has_error_code=0
> +idtentry xenint3 do_int3 has_error_code=0
> #endif
>
> idtentry general_protection do_general_protection has_error_code=1
> @@ -1227,6 +1223,7 @@ ENTRY(error_exit)
> END(error_exit)
>
> /* Runs on exception stack */
> +/* XXX: broken on Xen PV */
> ENTRY(nmi)
> UNWIND_HINT_IRET_REGS
> /*
> --- a/arch/x86/entry/entry_64_compat.S
> +++ b/arch/x86/entry/entry_64_compat.S
> @@ -293,7 +293,6 @@ ENTRY(entry_INT80_compat)
> /*
> * Interrupts are off on entry.
> */
> - PARAVIRT_ADJUST_EXCEPTION_FRAME
> ASM_CLAC /* Do this early to minimize exposure */
> SWAPGS
>
> --- a/arch/x86/include/asm/paravirt.h
> +++ b/arch/x86/include/asm/paravirt.h
> @@ -960,11 +960,6 @@ extern void default_banner(void);
> #define GET_CR2_INTO_RAX \
> call PARA_INDIRECT(pv_mmu_ops+PV_MMU_read_cr2)
>
> -#define PARAVIRT_ADJUST_EXCEPTION_FRAME \
> - PARA_SITE(PARA_PATCH(pv_irq_ops, PV_IRQ_adjust_exception_frame), \
> - CLBR_NONE, \
> - call PARA_INDIRECT(pv_irq_ops+PV_IRQ_adjust_exception_frame))
> -
> #define USERGS_SYSRET64 \
> PARA_SITE(PARA_PATCH(pv_cpu_ops, PV_CPU_usergs_sysret64), \
> CLBR_NONE, \
> --- a/arch/x86/include/asm/paravirt_types.h
> +++ b/arch/x86/include/asm/paravirt_types.h
> @@ -195,10 +195,6 @@ struct pv_irq_ops {
>
> void (*safe_halt)(void);
> void (*halt)(void);
> -
> -#ifdef CONFIG_X86_64
> - void (*adjust_exception_frame)(void);
> -#endif
> } __no_randomize_layout;
>
> struct pv_mmu_ops {
> --- a/arch/x86/include/asm/proto.h
> +++ b/arch/x86/include/asm/proto.h
> @@ -24,6 +24,9 @@ void entry_SYSENTER_compat(void);
> void __end_entry_SYSENTER_compat(void);
> void entry_SYSCALL_compat(void);
> void entry_INT80_compat(void);
> +#if defined(CONFIG_X86_64) && defined(CONFIG_XEN_PV)
> +void xen_entry_INT80_compat(void);
> +#endif
> #endif
>
> void x86_configure_nx(void);
> --- a/arch/x86/include/asm/traps.h
> +++ b/arch/x86/include/asm/traps.h
> @@ -13,9 +13,6 @@ asmlinkage void divide_error(void);
> asmlinkage void debug(void);
> asmlinkage void nmi(void);
> asmlinkage void int3(void);
> -asmlinkage void xen_debug(void);
> -asmlinkage void xen_int3(void);
> -asmlinkage void xen_stack_segment(void);
> asmlinkage void overflow(void);
> asmlinkage void bounds(void);
> asmlinkage void invalid_op(void);
> --- a/arch/x86/kernel/asm-offsets_64.c
> +++ b/arch/x86/kernel/asm-offsets_64.c
> @@ -20,7 +20,6 @@ static char syscalls_ia32[] = {
> int main(void)
> {
> #ifdef CONFIG_PARAVIRT
> - OFFSET(PV_IRQ_adjust_exception_frame, pv_irq_ops, adjust_exception_frame);
> OFFSET(PV_CPU_usergs_sysret64, pv_cpu_ops, usergs_sysret64);
> OFFSET(PV_CPU_swapgs, pv_cpu_ops, swapgs);
> BLANK();
> --- a/arch/x86/kernel/paravirt.c
> +++ b/arch/x86/kernel/paravirt.c
> @@ -319,9 +319,6 @@ struct pv_time_ops pv_time_ops = {
> .irq_enable = __PV_IS_CALLEE_SAVE(native_irq_enable),
> .safe_halt = native_safe_halt,
> .halt = native_halt,
> -#ifdef CONFIG_X86_64
> - .adjust_exception_frame = paravirt_nop,
> -#endif
> };
>
> __visible struct pv_cpu_ops pv_cpu_ops = {
> --- a/arch/x86/xen/enlighten_pv.c
> +++ b/arch/x86/xen/enlighten_pv.c
> @@ -586,6 +586,68 @@ static void xen_write_ldt_entry(struct d
> preempt_enable();
> }
>
> +#ifdef CONFIG_X86_64
> +static struct {
> + void (*orig)(void);
> + void (*xen)(void);
> + bool ist_okay;
> +} trap_array[] = {
> + { debug, xen_xendebug, true },
> + { int3, xen_xenint3, true },
> + { double_fault, xen_double_fault, true },
> +#ifdef CONFIG_X86_MCE
> + { machine_check, xen_machine_check, true },
> +#endif
> + { nmi, xen_nmi, true },
> + { overflow, xen_overflow, false },
> +#ifdef CONFIG_IA32_EMULATION
> + { entry_INT80_compat, xen_entry_INT80_compat, false },
> +#endif
> + { page_fault, xen_page_fault, false },
> + { divide_error, xen_divide_error, false },
> + { bounds, xen_bounds, false },
> + { invalid_op, xen_invalid_op, false },
> + { device_not_available, xen_device_not_available, false },
> + { coprocessor_segment_overrun, xen_coprocessor_segment_overrun, false },
> + { invalid_TSS, xen_invalid_TSS, false },
> + { segment_not_present, xen_segment_not_present, false },
> + { stack_segment, xen_stack_segment, false },
> + { general_protection, xen_general_protection, false },
> + { spurious_interrupt_bug, xen_spurious_interrupt_bug, false },
> + { coprocessor_error, xen_coprocessor_error, false },
> + { alignment_check, xen_alignment_check, false },
> + { simd_coprocessor_error, xen_simd_coprocessor_error, false },
> +#ifdef CONFIG_TRACING
> + { trace_page_fault, xen_trace_page_fault, false },
> +#endif
> +};
> +
> +static bool get_trap_addr(unsigned long *addr, unsigned int ist)
> +{
> + unsigned int nr;
> + bool ist_okay = false;
> +
> + /*
> + * Replace trap handler addresses by Xen specific ones.
> + * Check for known traps using IST and whitelist them.
> + * The debugger ones are the only ones we care about.
> + * Xen will handle faults like double_fault, * so we should never see
> + * them. Warn if there's an unexpected IST-using fault handler.
> + */
> + for (nr = 0; nr < ARRAY_SIZE(trap_array); nr++)
> + if (*addr == (unsigned long)trap_array[nr].orig) {
> + *addr = (unsigned long)trap_array[nr].xen;
> + ist_okay = trap_array[nr].ist_okay;
> + break;
> + }
> +
> + if (WARN_ON(ist != 0 && !ist_okay))
> + return false;
> +
> + return true;
> +}
> +#endif
> +
> static int cvt_gate_to_trap(int vector, const gate_desc *val,
> struct trap_info *info)
> {
> @@ -598,40 +660,8 @@ static int cvt_gate_to_trap(int vector,
>
> addr = gate_offset(val);
> #ifdef CONFIG_X86_64
> - /*
> - * Look for known traps using IST, and substitute them
> - * appropriately. The debugger ones are the only ones we care
> - * about. Xen will handle faults like double_fault,
> - * so we should never see them. Warn if
> - * there's an unexpected IST-using fault handler.
> - */
> - if (addr == (unsigned long)debug)
> - addr = (unsigned long)xen_debug;
> - else if (addr == (unsigned long)int3)
> - addr = (unsigned long)xen_int3;
> - else if (addr == (unsigned long)stack_segment)
> - addr = (unsigned long)xen_stack_segment;
> - else if (addr == (unsigned long)double_fault) {
> - /* Don't need to handle these */
> + if (!get_trap_addr(&addr, val->bits.ist))
> return 0;
> -#ifdef CONFIG_X86_MCE
> - } else if (addr == (unsigned long)machine_check) {
> - /*
> - * when xen hypervisor inject vMCE to guest,
> - * use native mce handler to handle it
> - */
> - ;
> -#endif
> - } else if (addr == (unsigned long)nmi)
> - /*
> - * Use the native version as well.
> - */
> - ;
> - else {
> - /* Some other trap using IST? */
> - if (WARN_ON(val->bits.ist != 0))
> - return 0;
> - }
> #endif /* CONFIG_X86_64 */
> info->address = addr;
>
> --- a/arch/x86/xen/irq.c
> +++ b/arch/x86/xen/irq.c
> @@ -123,9 +123,6 @@ static const struct pv_irq_ops xen_irq_o
>
> .safe_halt = xen_safe_halt,
> .halt = xen_halt,
> -#ifdef CONFIG_X86_64
> - .adjust_exception_frame = xen_adjust_exception_frame,
> -#endif
> };
>
> void __init xen_init_irq_ops(void)
> --- a/arch/x86/xen/xen-ops.h
> +++ b/arch/x86/xen/xen-ops.h
> @@ -138,7 +138,6 @@ static inline void __init xen_efi_init(v
> __visible void xen_iret(void);
> __visible void xen_sysret32(void);
> __visible void xen_sysret64(void);
> -__visible void xen_adjust_exception_frame(void);
>
> extern int xen_panic_handler_init(void);
>
>

You missed the updates to arch/x86/xen/xen-asm_64.S and the declarations
of the xen specific trap entries in arch/x86/include/asm/traps.h

Juergen