Hardcode the EPT page-walk level for L2 to be 4 levels, as KVM's MMU
currently also hardcodes the page walk level for nested EPT to be 4
levels. The L2 guest is all but guaranteed to soft hang on its first
instruction when L1 is using EPT, as KVM will construct 4-level page
tables and then tell hardware to use 5-level page tables.
Fixes: 855feb673640 ("KVM: MMU: Add 5 level EPT & Shadow page table support.")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
---
arch/x86/kvm/vmx/vmx.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 9a6664886f2e..ed1d41f5f505 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2947,6 +2947,9 @@ void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
static int get_ept_level(struct kvm_vcpu *vcpu)
{
+ /* Nested EPT currently only supports 4-level walks. */
+ if (is_guest_mode(vcpu) && nested_cpu_has_ept(get_vmcs12(vcpu)))
+ return 4;
if (cpu_has_vmx_ept_5levels() && (cpuid_maxphyaddr(vcpu) > 48))
return 5;
return 4;
--
2.24.1
