46 lines
1.2 KiB
C
46 lines
1.2 KiB
C
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// SPDX-License-Identifier: GPL-2.0-only
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/*
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* tools/testing/selftests/kvm/lib/x86_64/processor.c
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*
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* Copyright (C) 2021, Google LLC.
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*/
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#include "apic.h"
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void apic_disable(void)
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{
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wrmsr(MSR_IA32_APICBASE,
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rdmsr(MSR_IA32_APICBASE) &
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~(MSR_IA32_APICBASE_ENABLE | MSR_IA32_APICBASE_EXTD));
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}
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void xapic_enable(void)
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{
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uint64_t val = rdmsr(MSR_IA32_APICBASE);
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/* Per SDM: to enable xAPIC when in x2APIC must first disable APIC */
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if (val & MSR_IA32_APICBASE_EXTD) {
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apic_disable();
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wrmsr(MSR_IA32_APICBASE,
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rdmsr(MSR_IA32_APICBASE) | MSR_IA32_APICBASE_ENABLE);
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} else if (!(val & MSR_IA32_APICBASE_ENABLE)) {
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wrmsr(MSR_IA32_APICBASE, val | MSR_IA32_APICBASE_ENABLE);
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}
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/*
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* Per SDM: reset value of spurious interrupt vector register has the
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* APIC software enabled bit=0. It must be enabled in addition to the
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* enable bit in the MSR.
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*/
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val = xapic_read_reg(APIC_SPIV) | APIC_SPIV_APIC_ENABLED;
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xapic_write_reg(APIC_SPIV, val);
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}
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void x2apic_enable(void)
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{
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wrmsr(MSR_IA32_APICBASE, rdmsr(MSR_IA32_APICBASE) |
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MSR_IA32_APICBASE_ENABLE | MSR_IA32_APICBASE_EXTD);
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x2apic_write_reg(APIC_SPIV,
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x2apic_read_reg(APIC_SPIV) | APIC_SPIV_APIC_ENABLED);
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}
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