[PATCH 2/2] KVM: nVMX: Check guest activity state on vmentry of nested guests

[Nikita Leshenko <nikita.leshchenko@xxxxxxxxxx>]

The checks are written in the same order and structure as they appear in "SDM
26.3.1.5 - Checks on Guest Non-Register State", to ease verification.

Reviewed-by: Liran Alon <liran.alon@xxxxxxxxxx>
Reviewed-by: Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>
Signed-off-by: Nikita Leshenko <nikita.leshchenko@xxxxxxxxxx>
---
 arch/x86/kvm/vmx/nested.c | 24 ++++++++++++++++++++++++
 arch/x86/kvm/vmx/vmcs.h   | 13 +++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 24734946ec75..e2ee217f8ffe 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2666,10 +2666,34 @@ static int nested_vmx_check_vmcs_link_ptr(struct kvm_vcpu *vcpu,
  */
 static int nested_check_guest_non_reg_state(struct vmcs12 *vmcs12)
 {
+	/* Activity state must contain supported value */
 	if (vmcs12->guest_activity_state != GUEST_ACTIVITY_ACTIVE &&
 	    vmcs12->guest_activity_state != GUEST_ACTIVITY_HLT)
 		return -EINVAL;
 
+	/* Must not be HLT if SS DPL is not 0 */
+	if (VMX_AR_DPL(vmcs12->guest_ss_ar_bytes) != 0 &&
+	    vmcs12->guest_activity_state == GUEST_ACTIVITY_HLT)
+		return -EINVAL;
+
+	/* Must be active if blocking by MOV-SS or STI */
+	if ((vmcs12->guest_interruptibility_info &
+	    (GUEST_INTR_STATE_MOV_SS | GUEST_INTR_STATE_STI)) &&
+	    vmcs12->guest_activity_state != GUEST_ACTIVITY_ACTIVE)
+		return -EINVAL;
+
+	/* In HLT, only some interruptions are allowed */
+	if (vmcs12->vm_entry_intr_info_field & INTR_INFO_VALID_MASK &&
+	    vmcs12->guest_activity_state == GUEST_ACTIVITY_HLT) {
+		u32 intr_info = vmcs12->vm_entry_intr_info_field;
+		if (!is_ext_interrupt(intr_info) &&
+		    !is_nmi(intr_info) &&
+		    !is_debug(intr_info) &&
+		    !is_machine_check(intr_info) &&
+		    !is_mtf(intr_info))
+		    return -EINVAL;
+	}
+
 	return 0;
 }
 
diff --git a/arch/x86/kvm/vmx/vmcs.h b/arch/x86/kvm/vmx/vmcs.h
index cb6079f8a227..c5577c40b19d 100644
--- a/arch/x86/kvm/vmx/vmcs.h
+++ b/arch/x86/kvm/vmx/vmcs.h
@@ -102,6 +102,13 @@ static inline bool is_machine_check(u32 intr_info)
 		(INTR_TYPE_HARD_EXCEPTION | MC_VECTOR | INTR_INFO_VALID_MASK);
 }
 
+static inline bool is_mtf(u32 intr_info)
+{
+	return (intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VECTOR_MASK |
+			     INTR_INFO_VALID_MASK)) ==
+		(INTR_TYPE_OTHER_EVENT | 0 | INTR_INFO_VALID_MASK);
+}
+
 /* Undocumented: icebp/int1 */
 static inline bool is_icebp(u32 intr_info)
 {
@@ -115,6 +122,12 @@ static inline bool is_nmi(u32 intr_info)
 		== (INTR_TYPE_NMI_INTR | INTR_INFO_VALID_MASK);
 }
 
+static inline bool is_ext_interrupt(u32 intr_info)
+{
+	return (intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VALID_MASK))
+		== (INTR_TYPE_EXT_INTR | INTR_INFO_VALID_MASK);
+}
+
 enum vmcs_field_width {
 	VMCS_FIELD_WIDTH_U16 = 0,
 	VMCS_FIELD_WIDTH_U64 = 1,
-- 
2.20.1