KVM: SVM: Implement GIF, clgi and stgi

This patch implements the GIF flag and the clgi and stgi instructions that
set this flag. Only if the flag is set (default), interrupts can be received by
the CPU.

To keep the information about that somewhere, this patch adds a new hidden
flags vector. that is used to store information that does not go into the
vmcb, but is SVM specific.

I tried to write some code to make -no-kvm-irqchip work too, but the first
level guest won't even boot with that atm, so I ditched it.

v2 moves the hflags to x86 generic code
v3 makes use of the new permission helper
v6 only enables interrupt_window if GIF=1
Acked-by: NJoerg Roedel <joro@8bytes.org>
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -259,6 +259,7 @@ struct kvm_vcpu_arch {
 	unsigned long cr3;
 	unsigned long cr4;
 	unsigned long cr8;
+	u32 hflags;
 	u64 pdptrs[4]; /* pae */
 	u64 shadow_efer;
 	u64 apic_base;
@@ -738,6 +739,8 @@ enum {
 	TASK_SWITCH_GATE = 3,
 };
 
+#define HF_GIF_MASK		(1 << 0)
+
 /*
  * Hardware virtualization extension instructions may fault if a
  * reboot turns off virtualization while processes are running.

arch/x86/kvm/svm.c

@@ -251,7 +251,7 @@ static void skip_emulated_instruction(struct kvm_vcpu *vcpu)
 	kvm_rip_write(vcpu, svm->next_rip);
 	svm->vmcb->control.int_state &= ~SVM_INTERRUPT_SHADOW_MASK;
 
-	vcpu->arch.interrupt_window_open = 1;
+	vcpu->arch.interrupt_window_open = (svm->vcpu.arch.hflags & HF_GIF_MASK);
 }
 
 static int has_svm(void)
@@ -600,6 +600,8 @@ static void init_vmcb(struct vcpu_svm *svm)
 		save->cr4 = 0;
 	}
 	force_new_asid(&svm->vcpu);
+
+	svm->vcpu.arch.hflags = HF_GIF_MASK;
 }
 
 static int svm_vcpu_reset(struct kvm_vcpu *vcpu)
@@ -1234,6 +1236,36 @@ static int nested_svm_do(struct vcpu_svm *svm,
 	return retval;
 }
 
+static int stgi_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
+{
+	if (nested_svm_check_permissions(svm))
+		return 1;
+
+	svm->next_rip = kvm_rip_read(&svm->vcpu) + 3;
+	skip_emulated_instruction(&svm->vcpu);
+
+	svm->vcpu.arch.hflags |= HF_GIF_MASK;
+
+	return 1;
+}
+
+static int clgi_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
+{
+	if (nested_svm_check_permissions(svm))
+		return 1;
+
+	svm->next_rip = kvm_rip_read(&svm->vcpu) + 3;
+	skip_emulated_instruction(&svm->vcpu);
+
+	svm->vcpu.arch.hflags &= ~HF_GIF_MASK;
+
+	/* After a CLGI no interrupts should come */
+	svm_clear_vintr(svm);
+	svm->vmcb->control.int_ctl &= ~V_IRQ_MASK;
+
+	return 1;
+}
+
 static int invalid_op_interception(struct vcpu_svm *svm,
 				   struct kvm_run *kvm_run)
 {
@@ -1535,8 +1567,8 @@ static int (*svm_exit_handlers[])(struct vcpu_svm *svm,
 	[SVM_EXIT_VMMCALL]			= vmmcall_interception,
 	[SVM_EXIT_VMLOAD]			= invalid_op_interception,
 	[SVM_EXIT_VMSAVE]			= invalid_op_interception,
-	[SVM_EXIT_STGI]				= invalid_op_interception,
-	[SVM_EXIT_CLGI]				= invalid_op_interception,
+	[SVM_EXIT_STGI]				= stgi_interception,
+	[SVM_EXIT_CLGI]				= clgi_interception,
 	[SVM_EXIT_SKINIT]			= invalid_op_interception,
 	[SVM_EXIT_WBINVD]                       = emulate_on_interception,
 	[SVM_EXIT_MONITOR]			= invalid_op_interception,
@@ -1684,6 +1716,9 @@ static void svm_intr_assist(struct kvm_vcpu *vcpu)
 	if (!kvm_cpu_has_interrupt(vcpu))
 		goto out;
 
+	if (!(svm->vcpu.arch.hflags & HF_GIF_MASK))
+		goto out;
+
 	if (!(vmcb->save.rflags & X86_EFLAGS_IF) ||
 	    (vmcb->control.int_state & SVM_INTERRUPT_SHADOW_MASK) ||
 	    (vmcb->control.event_inj & SVM_EVTINJ_VALID)) {
@@ -1710,7 +1745,8 @@ static void kvm_reput_irq(struct vcpu_svm *svm)
 	}
 
 	svm->vcpu.arch.interrupt_window_open =
-		!(control->int_state & SVM_INTERRUPT_SHADOW_MASK);
+		!(control->int_state & SVM_INTERRUPT_SHADOW_MASK) &&
+		 (svm->vcpu.arch.hflags & HF_GIF_MASK);
 }
 
 static void svm_do_inject_vector(struct vcpu_svm *svm)
@@ -1734,7 +1770,8 @@ static void do_interrupt_requests(struct kvm_vcpu *vcpu,
 
 	svm->vcpu.arch.interrupt_window_open =
 		(!(control->int_state & SVM_INTERRUPT_SHADOW_MASK) &&
-		 (svm->vmcb->save.rflags & X86_EFLAGS_IF));
+		 (svm->vmcb->save.rflags & X86_EFLAGS_IF) &&
+		 (svm->vcpu.arch.hflags & HF_GIF_MASK));
 
 	if (svm->vcpu.arch.interrupt_window_open && svm->vcpu.arch.irq_summary)
 		/*