From:   isaku.yamahata@intel.com
To:     kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     isaku.yamahata@intel.com, isaku.yamahata@gmail.com,
        Paolo Bonzini <pbonzini@redhat.com>, erdemaktas@google.com,
        Sean Christopherson <seanjc@google.com>,
        Sagi Shahar <sagis@google.com>,
        David Matlack <dmatlack@google.com>,
        Kai Huang <kai.huang@intel.com>,
        Zhi Wang <zhi.wang.linux@gmail.com>
Subject: [PATCH v12 094/106] KVM: TDX: Silently ignore INIT/SIPI
Date:   Mon, 27 Feb 2023 00:23:33 -0800
Message-Id: <123833499f97111f361f304a67af1e86e04f9162.1677484918.git.isaku.yamahata@intel.com>
In-Reply-To: <cover.1677484918.git.isaku.yamahata@intel.com>
References: <cover.1677484918.git.isaku.yamahata@intel.com>
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From: Isaku Yamahata <isaku.yamahata@intel.com>

The TDX module API doesn't provide API for VMM to inject INIT IPI and SIPI.
Instead it defines the different protocols to boot application processors.
Ignore INIT and SIPI events for the TDX guest.

There are two options. 1) (silently) ignore INIT/SIPI request or 2) return
error to guest TDs somehow.  Given that TDX guest is paravirtualized to
boot AP, the option 1 is chosen for simplicity.

Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
 arch/x86/include/asm/kvm-x86-ops.h |  1 +
 arch/x86/include/asm/kvm_host.h    |  2 ++
 arch/x86/kvm/lapic.c               | 19 +++++++++++-------
 arch/x86/kvm/svm/svm.c             |  1 +
 arch/x86/kvm/vmx/main.c            | 32 ++++++++++++++++++++++++++++--
 arch/x86/kvm/vmx/tdx.c             |  4 ++--
 6 files changed, 48 insertions(+), 11 deletions(-)

diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index e1242c4b248f..5f699a93b9b3 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -144,6 +144,7 @@ KVM_X86_OP_OPTIONAL(migrate_timers)
 KVM_X86_OP(msr_filter_changed)
 KVM_X86_OP(complete_emulated_msr)
 KVM_X86_OP(vcpu_deliver_sipi_vector)
+KVM_X86_OP(vcpu_deliver_init)
 KVM_X86_OP_OPTIONAL_RET0(vcpu_get_apicv_inhibit_reasons);
 
 #undef KVM_X86_OP
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 301059b2e882..473b2538424a 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1786,6 +1786,7 @@ struct kvm_x86_ops {
 	int (*complete_emulated_msr)(struct kvm_vcpu *vcpu, int err);
 
 	void (*vcpu_deliver_sipi_vector)(struct kvm_vcpu *vcpu, u8 vector);
+	void (*vcpu_deliver_init)(struct kvm_vcpu *vcpu);
 
 	/*
 	 * Returns vCPU specific APICv inhibit reasons
@@ -1997,6 +1998,7 @@ void kvm_get_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg);
 void kvm_set_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg);
 int kvm_load_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector, int seg);
 void kvm_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, u8 vector);
+void kvm_vcpu_deliver_init(struct kvm_vcpu *vcpu);
 
 int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int idt_index,
 		    int reason, bool has_error_code, u32 error_code);
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index eae1459f8283..644a6a04fb56 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -3193,6 +3193,16 @@ int kvm_lapic_set_pv_eoi(struct kvm_vcpu *vcpu, u64 data, unsigned long len)
 	return 0;
 }
 
+void kvm_vcpu_deliver_init(struct kvm_vcpu *vcpu)
+{
+	kvm_vcpu_reset(vcpu, true);
+	if (kvm_vcpu_is_bsp(vcpu))
+		vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
+	else
+		vcpu->arch.mp_state = KVM_MP_STATE_INIT_RECEIVED;
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_deliver_init);
+
 int kvm_apic_accept_events(struct kvm_vcpu *vcpu)
 {
 	struct kvm_lapic *apic = vcpu->arch.apic;
@@ -3224,13 +3234,8 @@ int kvm_apic_accept_events(struct kvm_vcpu *vcpu)
 		return 0;
 	}
 
-	if (test_and_clear_bit(KVM_APIC_INIT, &apic->pending_events)) {
-		kvm_vcpu_reset(vcpu, true);
-		if (kvm_vcpu_is_bsp(apic->vcpu))
-			vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
-		else
-			vcpu->arch.mp_state = KVM_MP_STATE_INIT_RECEIVED;
-	}
+	if (test_and_clear_bit(KVM_APIC_INIT, &apic->pending_events))
+		static_call(kvm_x86_vcpu_deliver_init)(vcpu);
 	if (test_and_clear_bit(KVM_APIC_SIPI, &apic->pending_events)) {
 		if (vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED) {
 			/* evaluate pending_events before reading the vector */
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index d0b01956e420..bdb08dc236a1 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4830,6 +4830,7 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
 	.complete_emulated_msr = svm_complete_emulated_msr,
 
 	.vcpu_deliver_sipi_vector = svm_vcpu_deliver_sipi_vector,
+	.vcpu_deliver_init = kvm_vcpu_deliver_init,
 	.vcpu_get_apicv_inhibit_reasons = avic_vcpu_get_apicv_inhibit_reasons,
 };
 
diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
index 872479b8edb8..507a4b433ad0 100644
--- a/arch/x86/kvm/vmx/main.c
+++ b/arch/x86/kvm/vmx/main.c
@@ -310,6 +310,14 @@ static void vt_enable_smi_window(struct kvm_vcpu *vcpu)
 }
 #endif
 
+static bool vt_apic_init_signal_blocked(struct kvm_vcpu *vcpu)
+{
+	if (is_td_vcpu(vcpu))
+		return true;
+
+	return vmx_apic_init_signal_blocked(vcpu);
+}
+
 static void vt_apicv_post_state_restore(struct kvm_vcpu *vcpu)
 {
 	struct pi_desc *pi = vcpu_to_pi_desc(vcpu);
@@ -338,6 +346,25 @@ static void vt_deliver_interrupt(struct kvm_lapic *apic, int delivery_mode,
 	vmx_deliver_interrupt(apic, delivery_mode, trig_mode, vector);
 }
 
+static void vt_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, u8 vector)
+{
+	if (is_td_vcpu(vcpu))
+		return;
+
+	kvm_vcpu_deliver_sipi_vector(vcpu, vector);
+}
+
+static void vt_vcpu_deliver_init(struct kvm_vcpu *vcpu)
+{
+	if (is_td_vcpu(vcpu)) {
+		/* TDX doesn't support INIT.  Ignore INIT event */
+		vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
+		return;
+	}
+
+	kvm_vcpu_deliver_init(vcpu);
+}
+
 static void vt_flush_tlb_all(struct kvm_vcpu *vcpu)
 {
 	if (is_td_vcpu(vcpu)) {
@@ -702,13 +729,14 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
 #endif
 
 	.can_emulate_instruction = vmx_can_emulate_instruction,
-	.apic_init_signal_blocked = vmx_apic_init_signal_blocked,
+	.apic_init_signal_blocked = vt_apic_init_signal_blocked,
 	.migrate_timers = vmx_migrate_timers,
 
 	.msr_filter_changed = vt_msr_filter_changed,
 	.complete_emulated_msr = kvm_complete_insn_gp,
 
-	.vcpu_deliver_sipi_vector = kvm_vcpu_deliver_sipi_vector,
+	.vcpu_deliver_sipi_vector = vt_vcpu_deliver_sipi_vector,
+	.vcpu_deliver_init = vt_vcpu_deliver_init,
 
 	.dev_mem_enc_ioctl = tdx_dev_ioctl,
 	.mem_enc_ioctl = vt_mem_enc_ioctl,
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 01871f343ce2..6df79f3659b3 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -729,8 +729,8 @@ void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 {
 	struct msr_data apic_base_msr;
 
-	/* Ignore INIT silently because TDX doesn't support INIT event. */
-	if (init_event)
+	/* vcpu_deliver_init method silently discards INIT event. */
+	if (KVM_BUG_ON(init_event, vcpu->kvm))
 		return;
 	if (KVM_BUG_ON(is_td_vcpu_created(to_tdx(vcpu)), vcpu->kvm))
 		return;
-- 
2.25.1