[U-Boot] [PATCH 07/15] x86: Don't touch IA32_APIC_BASE MSR on Intel Quark

[Bin Meng]

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 at gmail.com>
---

 arch/x86/cpu/lapic.c | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/arch/x86/cpu/lapic.c b/arch/x86/cpu/lapic.c
index 30d2313..dbb32c4 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)
-- 
1.8.2.1