KVM: x86: INIT and reset sequences are different

x86 architecture defines differences between the reset and INIT sequences.
INIT does not initialize the FPU (including MMX, XMM, YMM, etc.), TSC, PMU,
MSRs (in general), MTRRs machine-check, APIC ID, APIC arbitration ID and BSP.

References (from Intel SDM):

"If the MP protocol has completed and a BSP is chosen, subsequent INITs (either
to a specific processor or system wide) do not cause the MP protocol to be
repeated." [8.4.2: MP Initialization Protocol Requirements and Restrictions]

[Table 9-1. IA-32 Processor States Following Power-up, Reset, or INIT]

"If the processor is reset by asserting the INIT# pin, the x87 FPU state is not
changed." [9.2: X87 FPU INITIALIZATION]

"The state of the local APIC following an INIT reset is the same as it is after
a power-up or hardware reset, except that the APIC ID and arbitration ID
registers are not affected." [10.4.7.3: Local APIC State After an INIT Reset
("Wait-for-SIPI" State)]

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Message-Id: <1428924848-28212-1-git-send-email-namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

5 files changed, 60 insertions, 48 deletions

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 4071eb161c8f..abf165330881 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1557,7 +1557,7 @@ void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value)
 
 }
 
-void kvm_lapic_reset(struct kvm_vcpu *vcpu)
+void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
 {
 	struct kvm_lapic *apic;
 	int i;
@@ -1571,7 +1571,8 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu)
 	/* Stop the timer in case it's a reset to an active apic */
 	hrtimer_cancel(&apic->lapic_timer.timer);
 
-	kvm_apic_set_id(apic, vcpu->vcpu_id);
+	if (!init_event)
+		kvm_apic_set_id(apic, vcpu->vcpu_id);
 	kvm_apic_set_version(apic->vcpu);
 
 	for (i = 0; i < APIC_LVT_NUM; i++)
@@ -1713,7 +1714,7 @@ int kvm_create_lapic(struct kvm_vcpu *vcpu)
 			APIC_DEFAULT_PHYS_BASE | MSR_IA32_APICBASE_ENABLE);
 
 	static_key_slow_inc(&apic_sw_disabled.key); /* sw disabled at reset */
-	kvm_lapic_reset(vcpu);
+	kvm_lapic_reset(vcpu, false);
 	kvm_iodevice_init(&apic->dev, &apic_mmio_ops);
 
 	return 0;
@@ -2047,8 +2048,8 @@ void kvm_apic_accept_events(struct kvm_vcpu *vcpu)
 	pe = xchg(&apic->pending_events, 0);
 
 	if (test_bit(KVM_APIC_INIT, &pe)) {
-		kvm_lapic_reset(vcpu);
-		kvm_vcpu_reset(vcpu);
+		kvm_lapic_reset(vcpu, true);
+		kvm_vcpu_reset(vcpu, true);
 		if (kvm_vcpu_is_bsp(apic->vcpu))
 			vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
 		else
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index 9d28383fc1e7..793f76183e8b 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -48,7 +48,7 @@ int kvm_apic_has_interrupt(struct kvm_vcpu *vcpu);
 int kvm_apic_accept_pic_intr(struct kvm_vcpu *vcpu);
 int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu);
 void kvm_apic_accept_events(struct kvm_vcpu *vcpu);
-void kvm_lapic_reset(struct kvm_vcpu *vcpu);
+void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event);
 u64 kvm_lapic_get_cr8(struct kvm_vcpu *vcpu);
 void kvm_lapic_set_tpr(struct kvm_vcpu *vcpu, unsigned long cr8);
 void kvm_lapic_set_eoi(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 46299dac7c6d..b6ad0f9de80a 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1082,7 +1082,7 @@ static u64 svm_compute_tsc_offset(struct kvm_vcpu *vcpu, u64 target_tsc)
 	return target_tsc - tsc;
 }
 
-static void init_vmcb(struct vcpu_svm *svm)
+static void init_vmcb(struct vcpu_svm *svm, bool init_event)
 {
 	struct vmcb_control_area *control = &svm->vmcb->control;
 	struct vmcb_save_area *save = &svm->vmcb->save;
@@ -1153,17 +1153,17 @@ static void init_vmcb(struct vcpu_svm *svm)
 	init_sys_seg(&save->ldtr, SEG_TYPE_LDT);
 	init_sys_seg(&save->tr, SEG_TYPE_BUSY_TSS16);
 
-	svm_set_efer(&svm->vcpu, 0);
+	if (!init_event)
+		svm_set_efer(&svm->vcpu, 0);
 	save->dr6 = 0xffff0ff0;
 	kvm_set_rflags(&svm->vcpu, 2);
 	save->rip = 0x0000fff0;
 	svm->vcpu.arch.regs[VCPU_REGS_RIP] = save->rip;
 
 	/*
-	 * This is the guest-visible cr0 value.
 	 * svm_set_cr0() sets PG and WP and clears NW and CD on save->cr0.
+	 * It also updates the guest-visible cr0 value.
 	 */
-	svm->vcpu.arch.cr0 = 0;
 	(void)kvm_set_cr0(&svm->vcpu, X86_CR0_NW | X86_CR0_CD | X86_CR0_ET);
 
 	save->cr4 = X86_CR4_PAE;
@@ -1195,13 +1195,19 @@ static void init_vmcb(struct vcpu_svm *svm)
 	enable_gif(svm);
 }
 
-static void svm_vcpu_reset(struct kvm_vcpu *vcpu)
+static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 	u32 dummy;
 	u32 eax = 1;
 
-	init_vmcb(svm);
+	if (!init_event) {
+		svm->vcpu.arch.apic_base = APIC_DEFAULT_PHYS_BASE |
+					   MSR_IA32_APICBASE_ENABLE;
+		if (kvm_vcpu_is_reset_bsp(&svm->vcpu))
+			svm->vcpu.arch.apic_base |= MSR_IA32_APICBASE_BSP;
+	}
+	init_vmcb(svm, init_event);
 
 	kvm_cpuid(vcpu, &eax, &dummy, &dummy, &dummy);
 	kvm_register_write(vcpu, VCPU_REGS_RDX, eax);
@@ -1257,12 +1263,7 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)
 	clear_page(svm->vmcb);
 	svm->vmcb_pa = page_to_pfn(page) << PAGE_SHIFT;
 	svm->asid_generation = 0;
-	init_vmcb(svm);
-
-	svm->vcpu.arch.apic_base = APIC_DEFAULT_PHYS_BASE |
-				   MSR_IA32_APICBASE_ENABLE;
-	if (kvm_vcpu_is_reset_bsp(&svm->vcpu))
-		svm->vcpu.arch.apic_base |= MSR_IA32_APICBASE_BSP;
+	init_vmcb(svm, false);
 
 	svm_init_osvw(&svm->vcpu);
 
@@ -1884,7 +1885,7 @@ static int shutdown_interception(struct vcpu_svm *svm)
 	 * so reinitialize it.
 	 */
 	clear_page(svm->vmcb);
-	init_vmcb(svm);
+	init_vmcb(svm, false);
 
 	kvm_run->exit_reason = KVM_EXIT_SHUTDOWN;
 	return 0;
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index f7b61687bd79..a694ff6bce80 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -4708,22 +4708,27 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx)
 	return 0;
 }
 
-static void vmx_vcpu_reset(struct kvm_vcpu *vcpu)
+static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 	struct msr_data apic_base_msr;
+	u64 cr0;
 
 	vmx->rmode.vm86_active = 0;
 
 	vmx->soft_vnmi_blocked = 0;
 
 	vmx->vcpu.arch.regs[VCPU_REGS_RDX] = get_rdx_init_val();
-	kvm_set_cr8(&vmx->vcpu, 0);
-	apic_base_msr.data = APIC_DEFAULT_PHYS_BASE | MSR_IA32_APICBASE_ENABLE;
-	if (kvm_vcpu_is_reset_bsp(&vmx->vcpu))
-		apic_base_msr.data |= MSR_IA32_APICBASE_BSP;
-	apic_base_msr.host_initiated = true;
-	kvm_set_apic_base(&vmx->vcpu, &apic_base_msr);
+	kvm_set_cr8(vcpu, 0);
+
+	if (!init_event) {
+		apic_base_msr.data = APIC_DEFAULT_PHYS_BASE |
+				     MSR_IA32_APICBASE_ENABLE;
+		if (kvm_vcpu_is_reset_bsp(vcpu))
+			apic_base_msr.data |= MSR_IA32_APICBASE_BSP;
+		apic_base_msr.host_initiated = true;
+		kvm_set_apic_base(vcpu, &apic_base_msr);
+	}
 
 	vmx_segment_cache_clear(vmx);
 
@@ -4747,9 +4752,12 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu)
 	vmcs_write32(GUEST_LDTR_LIMIT, 0xffff);
 	vmcs_write32(GUEST_LDTR_AR_BYTES, 0x00082);
 
-	vmcs_write32(GUEST_SYSENTER_CS, 0);
-	vmcs_writel(GUEST_SYSENTER_ESP, 0);
-	vmcs_writel(GUEST_SYSENTER_EIP, 0);
+	if (!init_event) {
+		vmcs_write32(GUEST_SYSENTER_CS, 0);
+		vmcs_writel(GUEST_SYSENTER_ESP, 0);
+		vmcs_writel(GUEST_SYSENTER_EIP, 0);
+		vmcs_write64(GUEST_IA32_DEBUGCTL, 0);
+	}
 
 	vmcs_writel(GUEST_RFLAGS, 0x02);
 	kvm_rip_write(vcpu, 0xfff0);
@@ -4764,18 +4772,15 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu)
 	vmcs_write32(GUEST_INTERRUPTIBILITY_INFO, 0);
 	vmcs_write32(GUEST_PENDING_DBG_EXCEPTIONS, 0);
 
-	/* Special registers */
-	vmcs_write64(GUEST_IA32_DEBUGCTL, 0);
-
 	setup_msrs(vmx);
 
 	vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, 0);  /* 22.2.1 */
 
-	if (cpu_has_vmx_tpr_shadow()) {
+	if (cpu_has_vmx_tpr_shadow() && !init_event) {
 		vmcs_write64(VIRTUAL_APIC_PAGE_ADDR, 0);
-		if (vm_need_tpr_shadow(vmx->vcpu.kvm))
+		if (vm_need_tpr_shadow(vcpu->kvm))
 			vmcs_write64(VIRTUAL_APIC_PAGE_ADDR,
-				     __pa(vmx->vcpu.arch.apic->regs));
+				     __pa(vcpu->arch.apic->regs));
 		vmcs_write32(TPR_THRESHOLD, 0);
 	}
 
@@ -4787,12 +4792,14 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu)
 	if (vmx->vpid != 0)
 		vmcs_write16(VIRTUAL_PROCESSOR_ID, vmx->vpid);
 
-	vmx->vcpu.arch.cr0 = X86_CR0_NW | X86_CR0_CD | X86_CR0_ET;
-	vmx_set_cr0(&vmx->vcpu, kvm_read_cr0(vcpu)); /* enter rmode */
-	vmx_set_cr4(&vmx->vcpu, 0);
-	vmx_set_efer(&vmx->vcpu, 0);
-	vmx_fpu_activate(&vmx->vcpu);
-	update_exception_bitmap(&vmx->vcpu);
+	cr0 = X86_CR0_NW | X86_CR0_CD | X86_CR0_ET;
+	vmx_set_cr0(vcpu, cr0); /* enter rmode */
+	vmx->vcpu.arch.cr0 = cr0;
+	vmx_set_cr4(vcpu, 0);
+	if (!init_event)
+		vmx_set_efer(vcpu, 0);
+	vmx_fpu_activate(vcpu);
+	update_exception_bitmap(vcpu);
 
 	vpid_sync_context(vmx);
 }
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0435b653f583..755a79fabfc1 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7033,7 +7033,7 @@ int kvm_arch_vcpu_ioctl_set_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
 	return 0;
 }
 
-int fx_init(struct kvm_vcpu *vcpu)
+int fx_init(struct kvm_vcpu *vcpu, bool init_event)
 {
 	int err;
 
@@ -7041,7 +7041,9 @@ int fx_init(struct kvm_vcpu *vcpu)
 	if (err)
 		return err;
 
-	fpu_finit(&vcpu->arch.guest_fpu);
+	if (!init_event)
+		fpu_finit(&vcpu->arch.guest_fpu);
+
 	if (cpu_has_xsaves)
 		vcpu->arch.guest_fpu.state->xsave.xsave_hdr.xcomp_bv =
 			host_xcr0 | XSTATE_COMPACTION_ENABLED;
@@ -7121,7 +7123,7 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
 	r = vcpu_load(vcpu);
 	if (r)
 		return r;
-	kvm_vcpu_reset(vcpu);
+	kvm_vcpu_reset(vcpu, false);
 	kvm_mmu_setup(vcpu);
 	vcpu_put(vcpu);
 
@@ -7159,7 +7161,7 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
 	kvm_x86_ops->vcpu_free(vcpu);
 }
 
-void kvm_vcpu_reset(struct kvm_vcpu *vcpu)
+void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 {
 	atomic_set(&vcpu->arch.nmi_queued, 0);
 	vcpu->arch.nmi_pending = 0;
@@ -7186,13 +7188,14 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu)
 	kvm_async_pf_hash_reset(vcpu);
 	vcpu->arch.apf.halted = false;
 
-	kvm_pmu_reset(vcpu);
+	if (!init_event)
+		kvm_pmu_reset(vcpu);
 
 	memset(vcpu->arch.regs, 0, sizeof(vcpu->arch.regs));
 	vcpu->arch.regs_avail = ~0;
 	vcpu->arch.regs_dirty = ~0;
 
-	kvm_x86_ops->vcpu_reset(vcpu);
+	kvm_x86_ops->vcpu_reset(vcpu, init_event);
 }
 
 void kvm_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, u8 vector)
@@ -7381,7 +7384,7 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
 		goto fail_free_mce_banks;
 	}
 
-	r = fx_init(vcpu);
+	r = fx_init(vcpu, false);
 	if (r)
 		goto fail_free_wbinvd_dirty_mask;