x86/entry: Add IRQENTRY_IRQ macro

Provide a seperate IDTENTRY macro for device interrupts. Similar to
IDTENTRY_ERRORCODE with the addition of invoking irq_enter/exit_rcu() and
providing the errorcode as a 'u8' argument to the C function, which
truncates the sign extended vector number.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/20200521202118.984573165@linutronix.de

arch/x86/entry/entry_32.S

@@ -751,6 +751,20 @@ SYM_CODE_START(\asmsym)
 SYM_CODE_END(\asmsym)
 .endm
 
+.macro idtentry_irq vector cfunc
+	.p2align CONFIG_X86_L1_CACHE_SHIFT
+SYM_CODE_START_LOCAL(asm_\cfunc)
+	ASM_CLAC
+	SAVE_ALL switch_stacks=1
+	ENCODE_FRAME_POINTER
+	movl	%esp, %eax
+	movl	PT_ORIG_EAX(%esp), %edx		/* get the vector from stack */
+	movl	$-1, PT_ORIG_EAX(%esp)		/* no syscall to restart */
+	call	\cfunc
+	jmp	handle_exception_return
+SYM_CODE_END(asm_\cfunc)
+.endm
+
 /*
  * Include the defines which emit the idt entries which are shared
  * shared between 32 and 64 bit.

arch/x86/entry/entry_64.S

@@ -527,6 +527,20 @@ _ASM_NOKPROBE(\asmsym)
 SYM_CODE_END(\asmsym)
 .endm
 
+/*
+ * Interrupt entry/exit.
+ *
+ + The interrupt stubs push (vector) onto the stack, which is the error_code
+ * position of idtentry exceptions, and jump to one of the two idtentry points
+ * (common/spurious).
+ *
+ * common_interrupt is a hotpath, align it to a cache line
+ */
+.macro idtentry_irq vector cfunc
+	.p2align CONFIG_X86_L1_CACHE_SHIFT
+	idtentry \vector asm_\cfunc \cfunc has_error_code=1
+.endm
+
 /*
  * MCE and DB exceptions
  */

arch/x86/include/asm/idtentry.h

@@ -165,6 +165,51 @@ __visible noinstr void func(struct pt_regs *regs)
 #define DEFINE_IDTENTRY_RAW_ERRORCODE(func)				\
 __visible noinstr void func(struct pt_regs *regs, unsigned long error_code)
 
+/**
+ * DECLARE_IDTENTRY_IRQ - Declare functions for device interrupt IDT entry
+ *			  points (common/spurious)
+ * @vector:	Vector number (ignored for C)
+ * @func:	Function name of the entry point
+ *
+ * Maps to DECLARE_IDTENTRY_ERRORCODE()
+ */
+#define DECLARE_IDTENTRY_IRQ(vector, func)				\
+	DECLARE_IDTENTRY_ERRORCODE(vector, func)
+
+/**
+ * DEFINE_IDTENTRY_IRQ - Emit code for device interrupt IDT entry points
+ * @func:	Function name of the entry point
+ *
+ * The vector number is pushed by the low level entry stub and handed
+ * to the function as error_code argument which needs to be truncated
+ * to an u8 because the push is sign extending.
+ *
+ * On 64-bit idtentry_enter/exit() are invoked in the ASM entry code before
+ * and after switching to the interrupt stack. On 32-bit this happens in C.
+ *
+ * irq_enter/exit_rcu() are invoked before the function body and the
+ * KVM L1D flush request is set.
+ */
+#define DEFINE_IDTENTRY_IRQ(func)					\
+static __always_inline void __##func(struct pt_regs *regs, u8 vector);	\
+									\
+__visible noinstr void func(struct pt_regs *regs,			\
+			    unsigned long error_code)			\
+{									\
+	bool rcu_exit = idtentry_enter_cond_rcu(regs);			\
+									\
+	instrumentation_begin();					\
+	irq_enter_rcu();						\
+	kvm_set_cpu_l1tf_flush_l1d();					\
+	__##func (regs, (u8)error_code);				\
+	irq_exit_rcu();							\
+	lockdep_hardirq_exit();						\
+	instrumentation_end();						\
+	idtentry_exit_cond_rcu(regs, rcu_exit);				\
+}									\
+									\
+static __always_inline void __##func(struct pt_regs *regs, u8 vector)
+
 /**
  * DECLARE_IDTENTRY_XENCB - Declare functions for XEN HV callback entry point
  * @vector:	Vector number (ignored for C)
@@ -312,6 +357,10 @@ __visible noinstr void func(struct pt_regs *regs,			\
 #define DECLARE_IDTENTRY_RAW_ERRORCODE(vector, func)			\
 	DECLARE_IDTENTRY_ERRORCODE(vector, func)
 
+/* Entries for common/spurious (device) interrupts */
+#define DECLARE_IDTENTRY_IRQ(vector, func)				\
+	idtentry_irq vector func
+
 #ifdef CONFIG_X86_64
 # define DECLARE_IDTENTRY_MCE(vector, func)				\
 	idtentry_mce_db vector asm_##func func