linux-kernel - [patch V9 23/39] x86/entry: Add IRQENTRY

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Date:   Thu, 21 May 2020 22:05:36 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Andy Lutomirski <luto@...nel.org>,
        Andrew Cooper <andrew.cooper3@...rix.com>,
        X86 ML <x86@...nel.org>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Brian Gerst <brgerst@...il.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Will Deacon <will@...nel.org>,
        Tom Lendacky <thomas.lendacky@....com>,
        Wei Liu <wei.liu@...nel.org>,
        Michael Kelley <mikelley@...rosoft.com>,
        Jason Chen CJ <jason.cj.chen@...el.com>,
        Zhao Yakui <yakui.zhao@...el.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>
Subject: [patch V9 23/39] x86/entry: Add IRQENTRY_IRQ macro

From: Thomas Gleixner <tglx@...utronix.de>

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@...utronix.de>
Acked-by: Andy Lutomirski <luto@...nel.org>
---
V9: Use cond RCU handling
---
 arch/x86/entry/entry_32.S       |   14 +++++++++++
 arch/x86/entry/entry_64.S       |   14 +++++++++++
 arch/x86/include/asm/idtentry.h |   48 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 76 insertions(+)

--- a/arch/x86/entry/entry_32.S
+++ b/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.
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -528,6 +528,20 @@ 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
  */
 #define CPU_TSS_IST(x) PER_CPU_VAR(cpu_tss_rw) + (TSS_ist + (x) * 8)
--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -165,6 +165,50 @@ static __always_inline void __##func(str
 #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 64bit dtentry_enter/exit() are invoked in the ASM entry code before
+ * and after switching to the interrupt stack. On 32bit 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)
 
 #ifdef CONFIG_X86_64
 /**
@@ -297,6 +341,10 @@ static __always_inline void __##func(str
 #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