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-rw-r--r--arch/x86/include/asm/irqflags.h56
-rw-r--r--arch/x86/include/asm/paravirt.h4
-rw-r--r--arch/x86/include/asm/paravirt_types.h1
3 files changed, 61 insertions, 0 deletions
diff --git a/arch/x86/include/asm/irqflags.h b/arch/x86/include/asm/irqflags.h
index 5745ce8bf10..fdf897373e1 100644
--- a/arch/x86/include/asm/irqflags.h
+++ b/arch/x86/include/asm/irqflags.h
@@ -56,6 +56,61 @@ static inline void native_halt(void)
#endif
+#ifdef CONFIG_X86_64
+/*
+ * Only returns from a trap or exception to a NMI context (intra-privilege
+ * level near return) to the same SS and CS segments. Should be used
+ * upon trap or exception return when nested over a NMI context so no iret is
+ * issued. It takes care of modifying the eflags, rsp and returning to the
+ * previous function.
+ *
+ * The stack, at that point, looks like :
+ *
+ * 0(rsp) RIP
+ * 8(rsp) CS
+ * 16(rsp) EFLAGS
+ * 24(rsp) RSP
+ * 32(rsp) SS
+ *
+ * Upon execution :
+ * Copy EIP to the top of the return stack
+ * Update top of return stack address
+ * Pop eflags into the eflags register
+ * Make the return stack current
+ * Near return (popping the return address from the return stack)
+ */
+#define NATIVE_INTERRUPT_RETURN_NMI_SAFE pushq %rax; \
+ movq %rsp, %rax; \
+ movq 24+8(%rax), %rsp; \
+ pushq 0+8(%rax); \
+ pushq 16+8(%rax); \
+ movq (%rax), %rax; \
+ popfq; \
+ ret
+#else
+/*
+ * Protected mode only, no V8086. Implies that protected mode must
+ * be entered before NMIs or MCEs are enabled. Only returns from a trap or
+ * exception to a NMI context (intra-privilege level far return). Should be used
+ * upon trap or exception return when nested over a NMI context so no iret is
+ * issued.
+ *
+ * The stack, at that point, looks like :
+ *
+ * 0(esp) EIP
+ * 4(esp) CS
+ * 8(esp) EFLAGS
+ *
+ * Upon execution :
+ * Copy the stack eflags to top of stack
+ * Pop eflags into the eflags register
+ * Far return: pop EIP and CS into their register, and additionally pop EFLAGS.
+ */
+#define NATIVE_INTERRUPT_RETURN_NMI_SAFE pushl 8(%esp); \
+ popfl; \
+ lret $4
+#endif
+
#ifdef CONFIG_PARAVIRT
#include <asm/paravirt.h>
#else
@@ -112,6 +167,7 @@ static inline unsigned long arch_local_irq_save(void)
#define ENABLE_INTERRUPTS(x) sti
#define DISABLE_INTERRUPTS(x) cli
+#define INTERRUPT_RETURN_NMI_SAFE NATIVE_INTERRUPT_RETURN_NMI_SAFE
#ifdef CONFIG_X86_64
#define SWAPGS swapgs
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index ebbc4d8ab17..1ef6906c179 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -962,6 +962,10 @@ extern void default_banner(void);
PARA_SITE(PARA_PATCH(pv_cpu_ops, PV_CPU_iret), CLBR_NONE, \
jmp PARA_INDIRECT(pv_cpu_ops+PV_CPU_iret))
+#define INTERRUPT_RETURN_NMI_SAFE \
+ PARA_SITE(PARA_PATCH(pv_cpu_ops, PV_CPU_nmi_return), CLBR_NONE, \
+ jmp *%cs:pv_cpu_ops+PV_CPU_nmi_return)
+
#define DISABLE_INTERRUPTS(clobbers) \
PARA_SITE(PARA_PATCH(pv_irq_ops, PV_IRQ_irq_disable), clobbers, \
PV_SAVE_REGS(clobbers | CLBR_CALLEE_SAVE); \
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index 82885099c86..3e0634cc127 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -181,6 +181,7 @@ struct pv_cpu_ops {
/* Normal iret. Jump to this with the standard iret stack
frame set up. */
void (*iret)(void);
+ void (*nmi_return)(void);
void (*swapgs)(void);