From: Sean Christopherson seanjc@google.com
[ Upstream commit a910b5ab6b250a88fff1866bf708642d83317466 ]
Make UMIP an "allowed-1" bit CR4_FIXED1 MSR when KVM is emulating UMIP. KVM emulates UMIP for both L1 and L2, and so should enumerate that L2 is allowed to have CR4.UMIP=1. Not setting the bit doesn't immediately break nVMX, as KVM does set/clear the bit in CR4_FIXED1 in response to a guest CPUID update, i.e. KVM will correctly (dis)allow nested VM-Entry based on whether or not UMIP is exposed to L1. That said, KVM should enumerate the bit as being allowed from time zero, e.g. userspace will see the wrong value if the MSR is read before CPUID is written.
Fixes: 0367f205a3b7 ("KVM: vmx: add support for emulating UMIP") Signed-off-by: Sean Christopherson seanjc@google.com Message-Id: 20220607213604.3346000-12-seanjc@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/kvm/vmx/nested.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 256a2aba830a..9f845556dde8 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -6736,6 +6736,9 @@ void nested_vmx_setup_ctls_msrs(struct nested_vmx_msrs *msrs, u32 ept_caps) rdmsrl(MSR_IA32_VMX_CR0_FIXED1, msrs->cr0_fixed1); rdmsrl(MSR_IA32_VMX_CR4_FIXED1, msrs->cr4_fixed1);
+ if (vmx_umip_emulated()) + msrs->cr4_fixed1 |= X86_CR4_UMIP; + msrs->vmcs_enum = nested_vmx_calc_vmcs_enum_msr(); }