According to section "Checks on Guest Control Registers, Debug Registers, and
and MSRs" in Intel SDM vol 3C, the following checks are performed on vmentry
of nested guests:
If the "load debug controls" VM-entry control is 1, bits reserved in the
IA32_DEBUGCTL MSR must be 0 in the field for that register. The first
processors to support the virtual-machine extensions supported only the
1-setting of this control and thus performed this check unconditionally.
Signed-off-by: Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>
Reviewed-by: Karl Heubaum <karl.heubaum@xxxxxxxxxx>
---
arch/x86/kvm/vmx/nested.c | 4 ++++
arch/x86/kvm/x86.h | 6 ++++++
2 files changed, 10 insertions(+)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 46af3a5e9209..0b234e95e0ed 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2677,6 +2677,10 @@ static int nested_vmx_check_guest_state(struct kvm_vcpu *vcpu,
!nested_guest_cr4_valid(vcpu, vmcs12->guest_cr4))
return -EINVAL;
+ if ((vmcs12->vm_entry_controls & VM_ENTRY_LOAD_DEBUG_CONTROLS) &&
+ !kvm_debugctl_valid(vmcs12->guest_ia32_debugctl))
+ return -EINVAL;
+
if ((vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_PAT) &&
!kvm_pat_valid(vmcs12->guest_ia32_pat))
return -EINVAL;
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index a470ff0868c5..28ba6d0c359f 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -354,6 +354,12 @@ static inline bool kvm_pat_valid(u64 data)
return (data | ((data & 0x0202020202020202ull) << 1)) == data;
}
+static inline bool kvm_debugctl_valid(u64 data)
+{
+ /* Bits 2, 3, 4, 5, 13 and [31:16] are reserved */
+ return ((data & 0xFFFFFFFFFFFF203Cull) ? false : true);
+}
+
void kvm_load_guest_xcr0(struct kvm_vcpu *vcpu);
void kvm_put_guest_xcr0(struct kvm_vcpu *vcpu);
--
2.20.1
