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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2021, Google LLC.
*/
#include "apic.h"
void apic_disable(void)
{
wrmsr(MSR_IA32_APICBASE,
rdmsr(MSR_IA32_APICBASE) &
~(MSR_IA32_APICBASE_ENABLE | MSR_IA32_APICBASE_EXTD));
}
void xapic_enable(void)
{
uint64_t val = rdmsr(MSR_IA32_APICBASE);
/* Per SDM: to enable xAPIC when in x2APIC must first disable APIC */
if (val & MSR_IA32_APICBASE_EXTD) {
apic_disable();
wrmsr(MSR_IA32_APICBASE,
rdmsr(MSR_IA32_APICBASE) | MSR_IA32_APICBASE_ENABLE);
} else if (!(val & MSR_IA32_APICBASE_ENABLE)) {
wrmsr(MSR_IA32_APICBASE, val | MSR_IA32_APICBASE_ENABLE);
}
/*
* Per SDM: reset value of spurious interrupt vector register has the
* APIC software enabled bit=0. It must be enabled in addition to the
* enable bit in the MSR.
*/
val = xapic_read_reg(APIC_SPIV) | APIC_SPIV_APIC_ENABLED;
xapic_write_reg(APIC_SPIV, val);
}
void x2apic_enable(void)
{
wrmsr(MSR_IA32_APICBASE, rdmsr(MSR_IA32_APICBASE) |
MSR_IA32_APICBASE_ENABLE | MSR_IA32_APICBASE_EXTD);
x2apic_write_reg(APIC_SPIV,
x2apic_read_reg(APIC_SPIV) | APIC_SPIV_APIC_ENABLED);
}
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