From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Felix Wilhelm Date: Mon, 11 Jun 2018 09:43:44 +0200 Subject: [PATCH] kvm: nVMX: Enforce cpl=0 for VMX instructions VMX instructions executed inside a L1 VM will always trigger a VM exit even when executed with cpl 3. This means we must perform the privilege check in software. Fixes: 70f3aac964ae("kvm: nVMX: Remove superfluous VMX instruction fault checks") Cc: stable@vger.kernel.org Signed-off-by: Felix Wilhelm Signed-off-by: Paolo Bonzini Signed-off-by: Thomas Lamprecht --- arch/x86/kvm/vmx.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 1a5617fc8b6a..5c8bd2d61080 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -7575,6 +7575,12 @@ static int handle_vmon(struct kvm_vcpu *vcpu) return 1; } + /* CPL=0 must be checked manually. */ + if (vmx_get_cpl(vcpu)) { + kvm_queue_exception(vcpu, UD_VECTOR); + return 1; + } + if (vmx->nested.vmxon) { nested_vmx_failValid(vcpu, VMXERR_VMXON_IN_VMX_ROOT_OPERATION); return kvm_skip_emulated_instruction(vcpu); @@ -7634,6 +7640,11 @@ static int handle_vmon(struct kvm_vcpu *vcpu) */ static int nested_vmx_check_permission(struct kvm_vcpu *vcpu) { + if (vmx_get_cpl(vcpu)) { + kvm_queue_exception(vcpu, UD_VECTOR); + return 0; + } + if (!to_vmx(vcpu)->nested.vmxon) { kvm_queue_exception(vcpu, UD_VECTOR); return 0; @@ -7967,7 +7978,7 @@ static int handle_vmread(struct kvm_vcpu *vcpu) if (get_vmx_mem_address(vcpu, exit_qualification, vmx_instruction_info, true, &gva)) return 1; - /* _system ok, as hardware has verified cpl=0 */ + /* _system ok, nested_vmx_check_permission has verified cpl=0 */ kvm_write_guest_virt_system(&vcpu->arch.emulate_ctxt, gva, &field_value, (is_long_mode(vcpu) ? 8 : 4), NULL); } @@ -8110,7 +8121,7 @@ static int handle_vmptrst(struct kvm_vcpu *vcpu) if (get_vmx_mem_address(vcpu, exit_qualification, vmx_instruction_info, true, &vmcs_gva)) return 1; - /* ok to use *_system, as hardware has verified cpl=0 */ + /* *_system ok, nested_vmx_check_permission has verified cpl=0 */ if (kvm_write_guest_virt_system(&vcpu->arch.emulate_ctxt, vmcs_gva, (void *)&to_vmx(vcpu)->nested.current_vmptr, sizeof(u64), &e)) {