From: Maxim Levitsky mlevitsk@redhat.com
commit af957eebfcc17433ee83ab85b1195a933ab5049c upstream.
When loading nested state, don't use check vcpu->arch.efer to get the L1 host's 64-bit vs. 32-bit state and don't check it for consistency with respect to VM_EXIT_HOST_ADDR_SPACE_SIZE, as register state in vCPU may be stale when KVM_SET_NESTED_STATE is called---and architecturally does not exist. When restoring L2 state in KVM, the CPU is placed in non-root where nested VMX code has no snapshot of L1 host state: VMX (conditionally) loads host state fields loaded on VM-exit, but they need not correspond to the state before entry. A simple case occurs in KVM itself, where the host RIP field points to vmx_vmexit rather than the instruction following vmlaunch/vmresume.
However, for the particular case of L1 being in 32- or 64-bit mode on entry, the exit controls can be treated instead as the source of truth regarding the state of L1 on entry, and can be used to check that vmcs12.VM_EXIT_HOST_ADDR_SPACE_SIZE matches vmcs12.HOST_EFER if vmcs12.VM_EXIT_LOAD_IA32_EFER is set. The consistency check on CPU EFER vs. vmcs12.VM_EXIT_HOST_ADDR_SPACE_SIZE, instead, happens only on VM-Enter. That's because, again, there's conceptually no "current" L1 EFER to check on KVM_SET_NESTED_STATE.
Suggested-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Maxim Levitsky mlevitsk@redhat.com Message-Id: 20211115131837.195527-2-mlevitsk@redhat.com Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kvm/vmx/nested.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-)
--- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -2854,6 +2854,17 @@ static int nested_vmx_check_controls(str return 0; }
+static int nested_vmx_check_address_space_size(struct kvm_vcpu *vcpu, + struct vmcs12 *vmcs12) +{ +#ifdef CONFIG_X86_64 + if (CC(!!(vmcs12->vm_exit_controls & VM_EXIT_HOST_ADDR_SPACE_SIZE) != + !!(vcpu->arch.efer & EFER_LMA))) + return -EINVAL; +#endif + return 0; +} + static int nested_vmx_check_host_state(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12) { @@ -2878,18 +2889,16 @@ static int nested_vmx_check_host_state(s return -EINVAL;
#ifdef CONFIG_X86_64 - ia32e = !!(vcpu->arch.efer & EFER_LMA); + ia32e = !!(vmcs12->vm_exit_controls & VM_EXIT_HOST_ADDR_SPACE_SIZE); #else ia32e = false; #endif
if (ia32e) { - if (CC(!(vmcs12->vm_exit_controls & VM_EXIT_HOST_ADDR_SPACE_SIZE)) || - CC(!(vmcs12->host_cr4 & X86_CR4_PAE))) + if (CC(!(vmcs12->host_cr4 & X86_CR4_PAE))) return -EINVAL; } else { - if (CC(vmcs12->vm_exit_controls & VM_EXIT_HOST_ADDR_SPACE_SIZE) || - CC(vmcs12->vm_entry_controls & VM_ENTRY_IA32E_MODE) || + if (CC(vmcs12->vm_entry_controls & VM_ENTRY_IA32E_MODE) || CC(vmcs12->host_cr4 & X86_CR4_PCIDE) || CC((vmcs12->host_rip) >> 32)) return -EINVAL; @@ -3559,6 +3568,9 @@ static int nested_vmx_run(struct kvm_vcp if (nested_vmx_check_controls(vcpu, vmcs12)) return nested_vmx_fail(vcpu, VMXERR_ENTRY_INVALID_CONTROL_FIELD);
+ if (nested_vmx_check_address_space_size(vcpu, vmcs12)) + return nested_vmx_fail(vcpu, VMXERR_ENTRY_INVALID_HOST_STATE_FIELD); + if (nested_vmx_check_host_state(vcpu, vmcs12)) return nested_vmx_fail(vcpu, VMXERR_ENTRY_INVALID_HOST_STATE_FIELD);