From: Bin Meng <bmeng.cn@gmail.com>
Date: Sun, 22 May 2016 08:45:31 +0000 (-0700)
Subject: x86: Don't touch IA32_APIC_BASE MSR on Intel Quark
X-Git-Tag: v2016.07-rc1~177^2~8
X-Git-Url: https://git.sur5r.net/?a=commitdiff_plain;h=3299be2479f9878dd3bb484f2b8f1ef7c0a20fb4;p=u-boot

x86: Don't touch IA32_APIC_BASE MSR on Intel Quark

Intel Quark processor core provides an integrated Local APIC but
does not support the IA32_APIC_BASE MSR. As a result, the Local
APIC is always globally enabled and the Local APIC base address
is fixed at 0xfee00000. Attempting to access the IA32_APIC_BASE
MSR causes a general protection fault.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
---

diff --git a/arch/x86/cpu/lapic.c b/arch/x86/cpu/lapic.c
index 30d23130eb..dbb32c4447 100644
--- a/arch/x86/cpu/lapic.c
+++ b/arch/x86/cpu/lapic.c
@@ -65,23 +65,27 @@ void lapic_write(unsigned long reg, unsigned long v)
 
 void enable_lapic(void)
 {
-	msr_t msr;
-
-	msr = msr_read(MSR_IA32_APICBASE);
-	msr.hi &= 0xffffff00;
-	msr.lo |= MSR_IA32_APICBASE_ENABLE;
-	msr.lo &= ~MSR_IA32_APICBASE_BASE;
-	msr.lo |= LAPIC_DEFAULT_BASE;
-	msr_write(MSR_IA32_APICBASE, msr);
+	if (!IS_ENABLED(CONFIG_INTEL_QUARK)) {
+		msr_t msr;
+
+		msr = msr_read(MSR_IA32_APICBASE);
+		msr.hi &= 0xffffff00;
+		msr.lo |= MSR_IA32_APICBASE_ENABLE;
+		msr.lo &= ~MSR_IA32_APICBASE_BASE;
+		msr.lo |= LAPIC_DEFAULT_BASE;
+		msr_write(MSR_IA32_APICBASE, msr);
+	}
 }
 
 void disable_lapic(void)
 {
-	msr_t msr;
+	if (!IS_ENABLED(CONFIG_INTEL_QUARK)) {
+		msr_t msr;
 
-	msr = msr_read(MSR_IA32_APICBASE);
-	msr.lo &= ~MSR_IA32_APICBASE_ENABLE;
-	msr_write(MSR_IA32_APICBASE, msr);
+		msr = msr_read(MSR_IA32_APICBASE);
+		msr.lo &= ~MSR_IA32_APICBASE_ENABLE;
+		msr_write(MSR_IA32_APICBASE, msr);
+	}
 }
 
 unsigned long lapicid(void)