Messages in this thread Patch in this message | | | From | Lai Jiangshan <> | Subject | [PATCH 2/4] x86/entry: Use asm_noist_exc_nmi() for NMI in early booting stage | Date | Tue, 27 Apr 2021 07:09:47 +0800 |
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From: Lai Jiangshan <laijs@linux.alibaba.com>
While the other entries for the exceptions which use Interrupt stacks can be also used on the kernel stack, asm_exc_nmi() can not be used on the kernel stack for it relies on the RSP-located "NMI executing" variable which expects to on a fixed location in the NMI IST stack. When it is unexpectedly called from the kernel stack, the RSP-located "NMI executing" variable is also on the kernel stack and is "uninitialized" and can cause the NMI entry to run in the wrong way.
Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Sean Christopherson <seanjc@google.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: Wanpeng Li <wanpengli@tencent.com> Cc: Jim Mattson <jmattson@google.com> Cc: Joerg Roedel <joro@8bytes.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Uros Bizjak <ubizjak@gmail.com> Cc: Maxim Levitsky <mlevitsk@redhat.com> Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com> --- arch/x86/include/asm/idtentry.h | 2 -- arch/x86/kernel/idt.c | 8 +++++++- arch/x86/kernel/nmi.c | 7 ++++--- 3 files changed, 11 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h index 5b11d2ddbb5c..0831c0da5957 100644 --- a/arch/x86/include/asm/idtentry.h +++ b/arch/x86/include/asm/idtentry.h @@ -589,9 +589,7 @@ DECLARE_IDTENTRY_RAW(X86_TRAP_MC, xenpv_exc_machine_check); /* NMI */ DECLARE_IDTENTRY_NMI(X86_TRAP_NMI, exc_nmi); -#ifdef CONFIG_XEN_PV DECLARE_IDTENTRY_RAW(X86_TRAP_NMI, noist_exc_nmi); -#endif /* #DB */ #ifdef CONFIG_X86_64 diff --git a/arch/x86/kernel/idt.c b/arch/x86/kernel/idt.c index d552f177eca0..c75409633f16 100644 --- a/arch/x86/kernel/idt.c +++ b/arch/x86/kernel/idt.c @@ -71,10 +71,16 @@ static const __initconst struct idt_data early_idts[] = { * cpu_init() is invoked. Interrupt stacks cannot be used at that point and * the traps which use them are reinitialized with IST after cpu_init() has * set up TSS. + * + * While the other entries for the exceptions which use Interrupt stacks can + * be also used on the kernel stack, asm_exc_nmi() can not be used on the + * kernel stack for it relies on the RSP-located "NMI executing" variable + * which expects to on a fixed location in the NMI IST stack. For early + * booting stage, asm_noist_exc_nmi() is used for NMI. */ static const __initconst struct idt_data def_idts[] = { INTG(X86_TRAP_DE, asm_exc_divide_error), - INTG(X86_TRAP_NMI, asm_exc_nmi), + INTG(X86_TRAP_NMI, asm_noist_exc_nmi), INTG(X86_TRAP_BR, asm_exc_bounds), INTG(X86_TRAP_UD, asm_exc_invalid_op), INTG(X86_TRAP_NM, asm_exc_device_not_available), diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c index 2b907a76d0a1..2fb1fd59d714 100644 --- a/arch/x86/kernel/nmi.c +++ b/arch/x86/kernel/nmi.c @@ -524,13 +524,14 @@ DEFINE_IDTENTRY_RAW(exc_nmi) mds_user_clear_cpu_buffers(); } -#ifdef CONFIG_XEN_PV DEFINE_IDTENTRY_RAW(noist_exc_nmi) { - /* On Xen PV, NMI doesn't use IST. The C part is the same as native. */ + /* + * On Xen PV and early booting stage, NMI doesn't use IST. + * The C part is the same as native. + */ exc_nmi(regs); } -#endif void stop_nmi(void) { -- 2.19.1.6.gb485710b
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