x86: APIC: remove apic_write_around(); use alternatives

Use alternatives to select the workaround for the 11AP Pentium erratum
for the affected steppings on the fly rather than build time.  Remove the
X86_GOOD_APIC configuration option and replace all the calls to
apic_write_around() with plain apic_write(), protecting accesses to the
ESR as appropriate due to the 3AP Pentium erratum.  Remove
apic_read_around() and all its invocations altogether as not needed.
Remove apic_write_atomic() and all its implementing backends.  The use of
ASM_OUTPUT2() is not strictly needed for input constraints, but I have
used it for readability's sake.

I had the feeling no one else was brave enough to do it, so I went ahead
and here it is.  Verified by checking the generated assembly and tested
with both a 32-bit and a 64-bit configuration, also with the 11AP
"feature" forced on and verified with gdb on /proc/kcore to work as
expected (as an 11AP machines are quite hard to get hands on these days).
Some script complained about the use of "volatile", but apic_write() needs
it for the same reason and is effectively a replacement for writel(), so I
have disregarded it.

I am not sure what the policy wrt defconfig files is, they are generated
and there is risk of a conflict resulting from an unrelated change, so I
have left changes to them out.  The option will get removed from them at
the next run.

Some testing with machines other than mine will be needed to avoid some
stupid mistake, but despite its volume, the change is not really that
intrusive, so I am fairly confident that because it works for me, it will
everywhere.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

13 files changed, 80 insertions, 113 deletions

diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu
index abff1b8..54b8c02 100644
--- a/arch/x86/Kconfig.cpu
+++ b/arch/x86/Kconfig.cpu
@@ -362,10 +362,6 @@ config X86_ALIGNMENT_16
 	def_bool y
 	depends on MWINCHIP3D || MWINCHIP2 || MWINCHIPC6 || MCYRIXIII || X86_ELAN || MK6 || M586MMX || M586TSC || M586 || M486 || MVIAC3_2 || MGEODEGX1
 
-config X86_GOOD_APIC
-	def_bool y
-	depends on MK7 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || MK8 || MEFFICEON || MCORE2 || MVIAC7 || X86_64
-
 config X86_INTEL_USERCOPY
 	def_bool y
 	depends on MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M586MMX || X86_GENERIC || MK8 || MK7 || MEFFICEON || MCORE2
diff --git a/arch/x86/kernel/apic_32.c b/arch/x86/kernel/apic_32.c
index a437d02..2bc1186 100644
--- a/arch/x86/kernel/apic_32.c
+++ b/arch/x86/kernel/apic_32.c
@@ -177,7 +177,7 @@ void __cpuinit enable_NMI_through_LVT0(void)
 	/* Level triggered for 82489DX */
 	if (!lapic_is_integrated())
 		v |= APIC_LVT_LEVEL_TRIGGER;
-	apic_write_around(APIC_LVT0, v);
+	apic_write(APIC_LVT0, v);
 }
 
 /**
@@ -212,9 +212,6 @@ int lapic_get_maxlvt(void)
  * this function twice on the boot CPU, once with a bogus timeout
  * value, second time for real. The other (noncalibrating) CPUs
  * call this function only once, with the real, calibrated value.
- *
- * We do reads before writes even if unnecessary, to get around the
- * P5 APIC double write bug.
  */
 static void __setup_APIC_LVTT(unsigned int clocks, int oneshot, int irqen)
 {
@@ -229,18 +226,18 @@ static void __setup_APIC_LVTT(unsigned int clocks, int oneshot, int irqen)
 	if (!irqen)
 		lvtt_value |= APIC_LVT_MASKED;
 
-	apic_write_around(APIC_LVTT, lvtt_value);
+	apic_write(APIC_LVTT, lvtt_value);
 
 	/*
 	 * Divide PICLK by 16
 	 */
 	tmp_value = apic_read(APIC_TDCR);
-	apic_write_around(APIC_TDCR, (tmp_value
-				& ~(APIC_TDR_DIV_1 | APIC_TDR_DIV_TMBASE))
-				| APIC_TDR_DIV_16);
+	apic_write(APIC_TDCR,
+		   (tmp_value & ~(APIC_TDR_DIV_1 | APIC_TDR_DIV_TMBASE)) |
+		   APIC_TDR_DIV_16);
 
 	if (!oneshot)
-		apic_write_around(APIC_TMICT, clocks/APIC_DIVISOR);
+		apic_write(APIC_TMICT, clocks / APIC_DIVISOR);
 }
 
 /*
@@ -249,7 +246,7 @@ static void __setup_APIC_LVTT(unsigned int clocks, int oneshot, int irqen)
 static int lapic_next_event(unsigned long delta,
 			    struct clock_event_device *evt)
 {
-	apic_write_around(APIC_TMICT, delta);
+	apic_write(APIC_TMICT, delta);
 	return 0;
 }
 
@@ -278,7 +275,7 @@ static void lapic_timer_setup(enum clock_event_mode mode,
 	case CLOCK_EVT_MODE_SHUTDOWN:
 		v = apic_read(APIC_LVTT);
 		v |= (APIC_LVT_MASKED | LOCAL_TIMER_VECTOR);
-		apic_write_around(APIC_LVTT, v);
+		apic_write(APIC_LVTT, v);
 		break;
 	case CLOCK_EVT_MODE_RESUME:
 		/* Nothing to do here */
@@ -693,44 +690,44 @@ void clear_local_APIC(void)
 	 */
 	if (maxlvt >= 3) {
 		v = ERROR_APIC_VECTOR; /* any non-zero vector will do */
-		apic_write_around(APIC_LVTERR, v | APIC_LVT_MASKED);
+		apic_write(APIC_LVTERR, v | APIC_LVT_MASKED);
 	}
 	/*
 	 * Careful: we have to set masks only first to deassert
 	 * any level-triggered sources.
 	 */
 	v = apic_read(APIC_LVTT);
-	apic_write_around(APIC_LVTT, v | APIC_LVT_MASKED);
+	apic_write(APIC_LVTT, v | APIC_LVT_MASKED);
 	v = apic_read(APIC_LVT0);
-	apic_write_around(APIC_LVT0, v | APIC_LVT_MASKED);
+	apic_write(APIC_LVT0, v | APIC_LVT_MASKED);
 	v = apic_read(APIC_LVT1);
-	apic_write_around(APIC_LVT1, v | APIC_LVT_MASKED);
+	apic_write(APIC_LVT1, v | APIC_LVT_MASKED);
 	if (maxlvt >= 4) {
 		v = apic_read(APIC_LVTPC);
-		apic_write_around(APIC_LVTPC, v | APIC_LVT_MASKED);
+		apic_write(APIC_LVTPC, v | APIC_LVT_MASKED);
 	}
 
 	/* lets not touch this if we didn't frob it */
 #ifdef CONFIG_X86_MCE_P4THERMAL
 	if (maxlvt >= 5) {
 		v = apic_read(APIC_LVTTHMR);
-		apic_write_around(APIC_LVTTHMR, v | APIC_LVT_MASKED);
+		apic_write(APIC_LVTTHMR, v | APIC_LVT_MASKED);
 	}
 #endif
 	/*
 	 * Clean APIC state for other OSs:
 	 */
-	apic_write_around(APIC_LVTT, APIC_LVT_MASKED);
-	apic_write_around(APIC_LVT0, APIC_LVT_MASKED);
-	apic_write_around(APIC_LVT1, APIC_LVT_MASKED);
+	apic_write(APIC_LVTT, APIC_LVT_MASKED);
+	apic_write(APIC_LVT0, APIC_LVT_MASKED);
+	apic_write(APIC_LVT1, APIC_LVT_MASKED);
 	if (maxlvt >= 3)
-		apic_write_around(APIC_LVTERR, APIC_LVT_MASKED);
+		apic_write(APIC_LVTERR, APIC_LVT_MASKED);
 	if (maxlvt >= 4)
-		apic_write_around(APIC_LVTPC, APIC_LVT_MASKED);
+		apic_write(APIC_LVTPC, APIC_LVT_MASKED);
 
 #ifdef CONFIG_X86_MCE_P4THERMAL
 	if (maxlvt >= 5)
-		apic_write_around(APIC_LVTTHMR, APIC_LVT_MASKED);
+		apic_write(APIC_LVTTHMR, APIC_LVT_MASKED);
 #endif
 	/* Integrated APIC (!82489DX) ? */
 	if (lapic_is_integrated()) {
@@ -756,7 +753,7 @@ void disable_local_APIC(void)
 	 */
 	value = apic_read(APIC_SPIV);
 	value &= ~APIC_SPIV_APIC_ENABLED;
-	apic_write_around(APIC_SPIV, value);
+	apic_write(APIC_SPIV, value);
 
 	/*
 	 * When LAPIC was disabled by the BIOS and enabled by the kernel,
@@ -865,8 +862,8 @@ void __init sync_Arb_IDs(void)
 	apic_wait_icr_idle();
 
 	apic_printk(APIC_DEBUG, "Synchronizing Arb IDs.\n");
-	apic_write_around(APIC_ICR, APIC_DEST_ALLINC | APIC_INT_LEVELTRIG
-				| APIC_DM_INIT);
+	apic_write(APIC_ICR,
+		   APIC_DEST_ALLINC | APIC_INT_LEVELTRIG | APIC_DM_INIT);
 }
 
 /*
@@ -902,16 +899,16 @@ void __init init_bsp_APIC(void)
 	else
 		value |= APIC_SPIV_FOCUS_DISABLED;
 	value |= SPURIOUS_APIC_VECTOR;
-	apic_write_around(APIC_SPIV, value);
+	apic_write(APIC_SPIV, value);
 
 	/*
 	 * Set up the virtual wire mode.
 	 */
-	apic_write_around(APIC_LVT0, APIC_DM_EXTINT);
+	apic_write(APIC_LVT0, APIC_DM_EXTINT);
 	value = APIC_DM_NMI;
 	if (!lapic_is_integrated())		/* 82489DX */
 		value |= APIC_LVT_LEVEL_TRIGGER;
-	apic_write_around(APIC_LVT1, value);
+	apic_write(APIC_LVT1, value);
 }
 
 static void __cpuinit lapic_setup_esr(void)
@@ -926,7 +923,7 @@ static void __cpuinit lapic_setup_esr(void)
 
 		/* enables sending errors */
 		value = ERROR_APIC_VECTOR;
-		apic_write_around(APIC_LVTERR, value);
+		apic_write(APIC_LVTERR, value);
 		/*
 		 * spec says clear errors after enabling vector.
 		 */
@@ -989,7 +986,7 @@ void __cpuinit setup_local_APIC(void)
 	 */
 	value = apic_read(APIC_TASKPRI);
 	value &= ~APIC_TPRI_MASK;
-	apic_write_around(APIC_TASKPRI, value);
+	apic_write(APIC_TASKPRI, value);
 
 	/*
 	 * After a crash, we no longer service the interrupts and a pending
@@ -1047,7 +1044,7 @@ void __cpuinit setup_local_APIC(void)
 	 * Set spurious IRQ vector
 	 */
 	value |= SPURIOUS_APIC_VECTOR;
-	apic_write_around(APIC_SPIV, value);
+	apic_write(APIC_SPIV, value);
 
 	/*
 	 * Set up LVT0, LVT1:
@@ -1069,7 +1066,7 @@ void __cpuinit setup_local_APIC(void)
 		apic_printk(APIC_VERBOSE, "masked ExtINT on CPU#%d\n",
 				smp_processor_id());
 	}
-	apic_write_around(APIC_LVT0, value);
+	apic_write(APIC_LVT0, value);
 
 	/*
 	 * only the BP should see the LINT1 NMI signal, obviously.
@@ -1080,7 +1077,7 @@ void __cpuinit setup_local_APIC(void)
 		value = APIC_DM_NMI | APIC_LVT_MASKED;
 	if (!integrated)		/* 82489DX */
 		value |= APIC_LVT_LEVEL_TRIGGER;
-	apic_write_around(APIC_LVT1, value);
+	apic_write(APIC_LVT1, value);
 }
 
 void __cpuinit end_local_APIC_setup(void)
@@ -1091,7 +1088,7 @@ void __cpuinit end_local_APIC_setup(void)
 	/* Disable the local apic timer */
 	value = apic_read(APIC_LVTT);
 	value |= (APIC_LVT_MASKED | LOCAL_TIMER_VECTOR);
-	apic_write_around(APIC_LVTT, value);
+	apic_write(APIC_LVTT, value);
 
 	setup_apic_nmi_watchdog(NULL);
 	apic_pm_activate();
@@ -1419,7 +1416,7 @@ void disconnect_bsp_APIC(int virt_wire_setup)
 		value &= ~APIC_VECTOR_MASK;
 		value |= APIC_SPIV_APIC_ENABLED;
 		value |= 0xf;
-		apic_write_around(APIC_SPIV, value);
+		apic_write(APIC_SPIV, value);
 
 		if (!virt_wire_setup) {
 			/*
@@ -1432,10 +1429,10 @@ void disconnect_bsp_APIC(int virt_wire_setup)
 				APIC_LVT_LEVEL_TRIGGER | APIC_LVT_MASKED);
 			value |= APIC_LVT_REMOTE_IRR | APIC_SEND_PENDING;
 			value = SET_APIC_DELIVERY_MODE(value, APIC_MODE_EXTINT);
-			apic_write_around(APIC_LVT0, value);
+			apic_write(APIC_LVT0, value);
 		} else {
 			/* Disable LVT0 */
-			apic_write_around(APIC_LVT0, APIC_LVT_MASKED);
+			apic_write(APIC_LVT0, APIC_LVT_MASKED);
 		}
 
 		/*
@@ -1449,7 +1446,7 @@ void disconnect_bsp_APIC(int virt_wire_setup)
 			APIC_LVT_LEVEL_TRIGGER | APIC_LVT_MASKED);
 		value |= APIC_LVT_REMOTE_IRR | APIC_SEND_PENDING;
 		value = SET_APIC_DELIVERY_MODE(value, APIC_MODE_NMI);
-		apic_write_around(APIC_LVT1, value);
+		apic_write(APIC_LVT1, value);
 	}
 }
 
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 1b1c56b..c9b58a8 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -131,13 +131,7 @@ static void __init check_popad(void)
  *   (for due to lack of "invlpg" and working WP on a i386)
  * - In order to run on anything without a TSC, we need to be
  *   compiled for a i486.
- * - In order to support the local APIC on a buggy Pentium machine,
- *   we need to be compiled with CONFIG_X86_GOOD_APIC disabled,
- *   which happens implicitly if compiled for a Pentium or lower
- *   (unless an advanced selection of CPU features is used) as an
- *   otherwise config implies a properly working local APIC without
- *   the need to do extra reads from the APIC.
-*/
+ */
 
 static void __init check_config(void)
 {
@@ -151,21 +145,6 @@ static void __init check_config(void)
 	if (boot_cpu_data.x86 == 3)
 		panic("Kernel requires i486+ for 'invlpg' and other features");
 #endif
-
-/*
- * If we were told we had a good local APIC, check for buggy Pentia,
- * i.e. all B steppings and the C2 stepping of P54C when using their
- * integrated APIC (see 11AP erratum in "Pentium Processor
- * Specification Update").
- */
-#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86_GOOD_APIC)
-	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL
-	    && cpu_has_apic
-	    && boot_cpu_data.x86 == 5
-	    && boot_cpu_data.x86_model == 2
-	    && (boot_cpu_data.x86_mask < 6 || boot_cpu_data.x86_mask == 11))
-		panic("Kernel compiled for PMMX+, assumes a local APIC without the read-before-write bug!");
-#endif
 }
 
 
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 70609ef..b75f256 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -227,6 +227,16 @@ static void __cpuinit init_intel(struct cpuinfo_x86 *c)
 	if (cpu_has_bts)
 		ds_init_intel(c);
 
+	/*
+	 * See if we have a good local APIC by checking for buggy Pentia,
+	 * i.e. all B steppings and the C2 stepping of P54C when using their
+	 * integrated APIC (see 11AP erratum in "Pentium Processor
+	 * Specification Update").
+	 */
+	if (cpu_has_apic && (c->x86<<8 | c->x86_model<<4) == 0x520 &&
+	    (c->x86_mask < 0x6 || c->x86_mask == 0xb))
+		set_cpu_cap(c, X86_FEATURE_11AP);
+
 #ifdef CONFIG_X86_NUMAQ
 	numaq_tsc_disable();
 #endif
diff --git a/arch/x86/kernel/cpu/mcheck/p4.c b/arch/x86/kernel/cpu/mcheck/p4.c
index eef001a..9b60fce 100644
--- a/arch/x86/kernel/cpu/mcheck/p4.c
+++ b/arch/x86/kernel/cpu/mcheck/p4.c
@@ -102,7 +102,7 @@ static void intel_init_thermal(struct cpuinfo_x86 *c)
 	/* The temperature transition interrupt handler setup */
 	h = THERMAL_APIC_VECTOR;		/* our delivery vector */
 	h |= (APIC_DM_FIXED | APIC_LVT_MASKED);	/* we'll mask till we're ready */
-	apic_write_around(APIC_LVTTHMR, h);
+	apic_write(APIC_LVTTHMR, h);
 
 	rdmsr(MSR_IA32_THERM_INTERRUPT, l, h);
 	wrmsr(MSR_IA32_THERM_INTERRUPT, l | 0x03 , h);
@@ -114,7 +114,7 @@ static void intel_init_thermal(struct cpuinfo_x86 *c)
 	wrmsr(MSR_IA32_MISC_ENABLE, l | (1<<3), h);
 
 	l = apic_read(APIC_LVTTHMR);
-	apic_write_around(APIC_LVTTHMR, l & ~APIC_LVT_MASKED);
+	apic_write(APIC_LVTTHMR, l & ~APIC_LVT_MASKED);
 	printk(KERN_INFO "CPU%d: Thermal monitoring enabled\n", cpu);
 
 	/* enable thermal throttle processing */
diff --git a/arch/x86/kernel/io_apic_32.c b/arch/x86/kernel/io_apic_32.c
index 558abf4..eabaf92 100644
--- a/arch/x86/kernel/io_apic_32.c
+++ b/arch/x86/kernel/io_apic_32.c
@@ -756,7 +756,7 @@ void send_IPI_self(int vector)
 	/*
 	 * Send the IPI. The write to APIC_ICR fires this off.
 	 */
-	apic_write_around(APIC_ICR, cfg);
+	apic_write(APIC_ICR, cfg);
 }
 #endif /* !CONFIG_SMP */
 
@@ -2030,7 +2030,7 @@ static void mask_lapic_irq(unsigned int irq)
 	unsigned long v;
 
 	v = apic_read(APIC_LVT0);
-	apic_write_around(APIC_LVT0, v | APIC_LVT_MASKED);
+	apic_write(APIC_LVT0, v | APIC_LVT_MASKED);
 }
 
 static void unmask_lapic_irq(unsigned int irq)
@@ -2038,7 +2038,7 @@ static void unmask_lapic_irq(unsigned int irq)
 	unsigned long v;
 
 	v = apic_read(APIC_LVT0);
-	apic_write_around(APIC_LVT0, v & ~APIC_LVT_MASKED);
+	apic_write(APIC_LVT0, v & ~APIC_LVT_MASKED);
 }
 
 static struct irq_chip lapic_chip __read_mostly = {
@@ -2168,7 +2168,7 @@ static inline void __init check_timer(void)
 	 * The AEOI mode will finish them in the 8259A
 	 * automatically.
 	 */
-	apic_write_around(APIC_LVT0, APIC_LVT_MASKED | APIC_DM_EXTINT);
+	apic_write(APIC_LVT0, APIC_LVT_MASKED | APIC_DM_EXTINT);
 	init_8259A(1);
 	timer_ack = (nmi_watchdog == NMI_IO_APIC && !APIC_INTEGRATED(ver));
 
@@ -2256,7 +2256,7 @@ static inline void __init check_timer(void)
 	printk(KERN_INFO "...trying to set up timer as Virtual Wire IRQ...");
 
 	lapic_register_intr(0, vector);
-	apic_write_around(APIC_LVT0, APIC_DM_FIXED | vector);	/* Fixed mode */
+	apic_write(APIC_LVT0, APIC_DM_FIXED | vector);	/* Fixed mode */
 	enable_8259A_irq(0);
 
 	if (timer_irq_works()) {
@@ -2264,14 +2264,14 @@ static inline void __init check_timer(void)
 		goto out;
 	}
 	disable_8259A_irq(0);
-	apic_write_around(APIC_LVT0, APIC_LVT_MASKED | APIC_DM_FIXED | vector);
+	apic_write(APIC_LVT0, APIC_LVT_MASKED | APIC_DM_FIXED | vector);
 	printk(" failed.\n");
 
 	printk(KERN_INFO "...trying to set up timer as ExtINT IRQ...");
 
 	init_8259A(0);
 	make_8259A_irq(0);
-	apic_write_around(APIC_LVT0, APIC_DM_EXTINT);
+	apic_write(APIC_LVT0, APIC_DM_EXTINT);
 
 	unlock_ExtINT_logic();
 
diff --git a/arch/x86/kernel/ipi.c b/arch/x86/kernel/ipi.c
index 9d98cda..3f7537b 100644
--- a/arch/x86/kernel/ipi.c
+++ b/arch/x86/kernel/ipi.c
@@ -70,7 +70,7 @@ void __send_IPI_shortcut(unsigned int shortcut, int vector)
 	/*
 	 * Send the IPI. The write to APIC_ICR fires this off.
 	 */
-	apic_write_around(APIC_ICR, cfg);
+	apic_write(APIC_ICR, cfg);
 }
 
 void send_IPI_self(int vector)
@@ -98,7 +98,7 @@ static inline void __send_IPI_dest_field(unsigned long mask, int vector)
 	 * prepare target chip field
 	 */
 	cfg = __prepare_ICR2(mask);
-	apic_write_around(APIC_ICR2, cfg);
+	apic_write(APIC_ICR2, cfg);
 
 	/*
 	 * program the ICR
@@ -108,7 +108,7 @@ static inline void __send_IPI_dest_field(unsigned long mask, int vector)
 	/*
 	 * Send the IPI. The write to APIC_ICR fires this off.
 	 */
-	apic_write_around(APIC_ICR, cfg);
+	apic_write(APIC_ICR, cfg);
 }
 
 /*
diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index ec024b3..384b49f 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -263,7 +263,7 @@ late_initcall(init_lapic_nmi_sysfs);
 
 static void __acpi_nmi_enable(void *__unused)
 {
-	apic_write_around(APIC_LVT0, APIC_DM_NMI);
+	apic_write(APIC_LVT0, APIC_DM_NMI);
 }
 
 /*
@@ -277,7 +277,7 @@ void acpi_nmi_enable(void)
 
 static void __acpi_nmi_disable(void *__unused)
 {
-	apic_write_around(APIC_LVT0, APIC_DM_NMI | APIC_LVT_MASKED);
+	apic_write(APIC_LVT0, APIC_DM_NMI | APIC_LVT_MASKED);
 }
 
 /*
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index e0f571d..5d7326a 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -361,7 +361,6 @@ struct pv_cpu_ops pv_cpu_ops = {
 struct pv_apic_ops pv_apic_ops = {
 #ifdef CONFIG_X86_LOCAL_APIC
 	.apic_write = native_apic_write,
-	.apic_write_atomic = native_apic_write_atomic,
 	.apic_read = native_apic_read,
 	.setup_boot_clock = setup_boot_APIC_clock,
 	.setup_secondary_clock = setup_secondary_APIC_clock,
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 687376a..f251f5c 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -546,8 +546,8 @@ static inline void __inquire_remote_apic(int apicid)
 			printk(KERN_CONT
 			       "a previous APIC delivery may have failed\n");
 
-		apic_write_around(APIC_ICR2, SET_APIC_DEST_FIELD(apicid));
-		apic_write_around(APIC_ICR, APIC_DM_REMRD | regs[i]);
+		apic_write(APIC_ICR2, SET_APIC_DEST_FIELD(apicid));
+		apic_write(APIC_ICR, APIC_DM_REMRD | regs[i]);
 
 		timeout = 0;
 		do {
@@ -579,11 +579,11 @@ wakeup_secondary_cpu(int logical_apicid, unsigned long start_eip)
 	int maxlvt;
 
 	/* Target chip */
-	apic_write_around(APIC_ICR2, SET_APIC_DEST_FIELD(logical_apicid));
+	apic_write(APIC_ICR2, SET_APIC_DEST_FIELD(logical_apicid));
 
 	/* Boot on the stack */
 	/* Kick the second */
-	apic_write_around(APIC_ICR, APIC_DM_NMI | APIC_DEST_LOGICAL);
+	apic_write(APIC_ICR, APIC_DM_NMI | APIC_DEST_LOGICAL);
 
 	Dprintk("Waiting for send to finish...\n");
 	send_status = safe_apic_wait_icr_idle();
@@ -592,14 +592,9 @@ wakeup_secondary_cpu(int logical_apicid, unsigned long start_eip)
 	 * Give the other CPU some time to accept the IPI.
 	 */
 	udelay(200);
-	/*
-	 * Due to the Pentium erratum 3AP.
-	 */
 	maxlvt = lapic_get_maxlvt();
-	if (maxlvt > 3) {
-		apic_read_around(APIC_SPIV);
+	if (maxlvt > 3)			/* Due to the Pentium erratum 3AP.  */
 		apic_write(APIC_ESR, 0);
-	}
 	accept_status = (apic_read(APIC_ESR) & 0xEF);
 	Dprintk("NMI sent.\n");
 
@@ -625,12 +620,14 @@ wakeup_secondary_cpu(int phys_apicid, unsigned long start_eip)
 		return send_status;
 	}
 
+	maxlvt = lapic_get_maxlvt();
+
 	/*
 	 * Be paranoid about clearing APIC errors.
 	 */
 	if (APIC_INTEGRATED(apic_version[phys_apicid])) {
-		apic_read_around(APIC_SPIV);
-		apic_write(APIC_ESR, 0);
+		if (maxlvt > 3)		/* Due to the Pentium erratum 3AP.  */
+			apic_write(APIC_ESR, 0);
 		apic_read(APIC_ESR);
 	}
 
@@ -639,13 +636,13 @@ wakeup_secondary_cpu(int phys_apicid, unsigned long start_eip)
 	/*
 	 * Turn INIT on target chip
 	 */
-	apic_write_around(APIC_ICR2, SET_APIC_DEST_FIELD(phys_apicid));
+	apic_write(APIC_ICR2, SET_APIC_DEST_FIELD(phys_apicid));
 
 	/*
 	 * Send IPI
 	 */
-	apic_write_around(APIC_ICR, APIC_INT_LEVELTRIG | APIC_INT_ASSERT
-				| APIC_DM_INIT);
+	apic_write(APIC_ICR,
+		   APIC_INT_LEVELTRIG | APIC_INT_ASSERT | APIC_DM_INIT);
 
 	Dprintk("Waiting for send to finish...\n");
 	send_status = safe_apic_wait_icr_idle();
@@ -655,10 +652,10 @@ wakeup_secondary_cpu(int phys_apicid, unsigned long start_eip)
 	Dprintk("Deasserting INIT.\n");
 
 	/* Target chip */
-	apic_write_around(APIC_ICR2, SET_APIC_DEST_FIELD(phys_apicid));
+	apic_write(APIC_ICR2, SET_APIC_DEST_FIELD(phys_apicid));
 
 	/* Send IPI */
-	apic_write_around(APIC_ICR, APIC_INT_LEVELTRIG | APIC_DM_INIT);
+	apic_write(APIC_ICR, APIC_INT_LEVELTRIG | APIC_DM_INIT);
 
 	Dprintk("Waiting for send to finish...\n");
 	send_status = safe_apic_wait_icr_idle();
@@ -689,12 +686,10 @@ wakeup_secondary_cpu(int phys_apicid, unsigned long start_eip)
 	 */
 	Dprintk("#startup loops: %d.\n", num_starts);
 
-	maxlvt = lapic_get_maxlvt();
-
 	for (j = 1; j <= num_starts; j++) {
 		Dprintk("Sending STARTUP #%d.\n", j);
-		apic_read_around(APIC_SPIV);
-		apic_write(APIC_ESR, 0);
+		if (maxlvt > 3)		/* Due to the Pentium erratum 3AP.  */
+			apic_write(APIC_ESR, 0);
 		apic_read(APIC_ESR);
 		Dprintk("After apic_write.\n");
 
@@ -703,12 +698,11 @@ wakeup_secondary_cpu(int phys_apicid, unsigned long start_eip)
 		 */
 
 		/* Target chip */
-		apic_write_around(APIC_ICR2, SET_APIC_DEST_FIELD(phys_apicid));
+		apic_write(APIC_ICR2, SET_APIC_DEST_FIELD(phys_apicid));
 
 		/* Boot on the stack */
 		/* Kick the second */
-		apic_write_around(APIC_ICR, APIC_DM_STARTUP
-					| (start_eip >> 12));
+		apic_write(APIC_ICR, APIC_DM_STARTUP | (start_eip >> 12));
 
 		/*
 		 * Give the other CPU some time to accept the IPI.
@@ -724,13 +718,8 @@ wakeup_secondary_cpu(int phys_apicid, unsigned long start_eip)
 		 * Give the other CPU some time to accept the IPI.
 		 */
 		udelay(200);
-		/*
-		 * Due to the Pentium erratum 3AP.
-		 */
-		if (maxlvt > 3) {
-			apic_read_around(APIC_SPIV);
+		if (maxlvt > 3)		/* Due to the Pentium erratum 3AP.  */
 			apic_write(APIC_ESR, 0);
-		}
 		accept_status = (apic_read(APIC_ESR) & 0xEF);
 		if (send_status || accept_status)
 			break;
diff --git a/arch/x86/kernel/vmi_32.c b/arch/x86/kernel/vmi_32.c
index b153460..0a1b1a9 100644
--- a/arch/x86/kernel/vmi_32.c
+++ b/arch/x86/kernel/vmi_32.c
@@ -906,7 +906,6 @@ static inline int __init activate_vmi(void)
 #ifdef CONFIG_X86_LOCAL_APIC
 	para_fill(pv_apic_ops.apic_read, APICRead);
 	para_fill(pv_apic_ops.apic_write, APICWrite);
-	para_fill(pv_apic_ops.apic_write_atomic, APICWrite);
 #endif
 
 	/*
diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index 50dad44..0313a5e 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -991,7 +991,6 @@ __init void lguest_init(void)
 #ifdef CONFIG_X86_LOCAL_APIC
 	/* apic read/write intercepts */
 	pv_apic_ops.apic_write = lguest_apic_write;
-	pv_apic_ops.apic_write_atomic = lguest_apic_write;
 	pv_apic_ops.apic_read = lguest_apic_read;
 #endif
 
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index bb50845..7f26c37 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1131,7 +1131,6 @@ static const struct pv_irq_ops xen_irq_ops __initdata = {
 static const struct pv_apic_ops xen_apic_ops __initdata = {
 #ifdef CONFIG_X86_LOCAL_APIC
 	.apic_write = xen_apic_write,
-	.apic_write_atomic = xen_apic_write,
 	.apic_read = xen_apic_read,
 	.setup_boot_clock = paravirt_nop,
 	.setup_secondary_clock = paravirt_nop,