KVM: nVMX: Implement VMCLEAR

This patch implements the VMCLEAR instruction.
Signed-off-by: Nadav Har'El <nyh@il.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

arch/x86/kvm/vmx.c

@@ -166,6 +166,9 @@ struct __packed vmcs12 {
 	u32 revision_id;
 	u32 abort;
 
+	u32 launch_state; /* set to 0 by VMCLEAR, to 1 by VMLAUNCH */
+	u32 padding[7]; /* room for future expansion */
+
 	u64 io_bitmap_a;
 	u64 io_bitmap_b;
 	u64 msr_bitmap;
@@ -4814,6 +4817,66 @@ static void nested_vmx_failValid(struct kvm_vcpu *vcpu,
 	get_vmcs12(vcpu)->vm_instruction_error = vm_instruction_error;
 }
 
+/* Emulate the VMCLEAR instruction */
+static int handle_vmclear(struct kvm_vcpu *vcpu)
+{
+	struct vcpu_vmx *vmx = to_vmx(vcpu);
+	gva_t gva;
+	gpa_t vmptr;
+	struct vmcs12 *vmcs12;
+	struct page *page;
+	struct x86_exception e;
+
+	if (!nested_vmx_check_permission(vcpu))
+		return 1;
+
+	if (get_vmx_mem_address(vcpu, vmcs_readl(EXIT_QUALIFICATION),
+			vmcs_read32(VMX_INSTRUCTION_INFO), &gva))
+		return 1;
+
+	if (kvm_read_guest_virt(&vcpu->arch.emulate_ctxt, gva, &vmptr,
+				sizeof(vmptr), &e)) {
+		kvm_inject_page_fault(vcpu, &e);
+		return 1;
+	}
+
+	if (!IS_ALIGNED(vmptr, PAGE_SIZE)) {
+		nested_vmx_failValid(vcpu, VMXERR_VMCLEAR_INVALID_ADDRESS);
+		skip_emulated_instruction(vcpu);
+		return 1;
+	}
+
+	if (vmptr == vmx->nested.current_vmptr) {
+		kunmap(vmx->nested.current_vmcs12_page);
+		nested_release_page(vmx->nested.current_vmcs12_page);
+		vmx->nested.current_vmptr = -1ull;
+		vmx->nested.current_vmcs12 = NULL;
+	}
+
+	page = nested_get_page(vcpu, vmptr);
+	if (page == NULL) {
+		/*
+		 * For accurate processor emulation, VMCLEAR beyond available
+		 * physical memory should do nothing at all. However, it is
+		 * possible that a nested vmx bug, not a guest hypervisor bug,
+		 * resulted in this case, so let's shut down before doing any
+		 * more damage:
+		 */
+		kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu);
+		return 1;
+	}
+	vmcs12 = kmap(page);
+	vmcs12->launch_state = 0;
+	kunmap(page);
+	nested_release_page(page);
+
+	nested_free_vmcs02(vmx, vmptr);
+
+	skip_emulated_instruction(vcpu);
+	nested_vmx_succeed(vcpu);
+	return 1;
+}
+
 /*
  * The exit handlers return 1 if the exit was handled fully and guest execution
  * may resume.  Otherwise they set the kvm_run parameter to indicate what needs
@@ -4835,7 +4898,7 @@ static int (*kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
 	[EXIT_REASON_INVD]		      = handle_invd,
 	[EXIT_REASON_INVLPG]		      = handle_invlpg,
 	[EXIT_REASON_VMCALL]                  = handle_vmcall,
-	[EXIT_REASON_VMCLEAR]	              = handle_vmx_insn,
+	[EXIT_REASON_VMCLEAR]	              = handle_vmclear,
 	[EXIT_REASON_VMLAUNCH]                = handle_vmx_insn,
 	[EXIT_REASON_VMPTRLD]                 = handle_vmx_insn,
 	[EXIT_REASON_VMPTRST]                 = handle_vmx_insn,

arch/x86/kvm/x86.c

@@ -347,6 +347,7 @@ void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault)
 	vcpu->arch.cr2 = fault->address;
 	kvm_queue_exception_e(vcpu, PF_VECTOR, fault->error_code);
 }
+EXPORT_SYMBOL_GPL(kvm_inject_page_fault);
 
 void kvm_propagate_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault)
 {