From 0a79b009525b160081d75cef5dbf45817956acf2 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Tue, 1 Sep 2009 12:03:25 +0300 Subject: KVM: VMX: Check cpl before emulating debug register access Debug registers may only be accessed from cpl 0. Unfortunately, vmx will code to emulate the instruction even though it was issued from guest userspace, possibly leading to an unexpected trap later. Cc: stable@kernel.org Signed-off-by: Avi Kivity Signed-off-by: Marcelo Tosatti --- arch/x86/kvm/x86.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'arch/x86/kvm/x86.c') diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 7627ff607a90..4137cc579ba5 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -222,6 +222,19 @@ void kvm_queue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code) } EXPORT_SYMBOL_GPL(kvm_queue_exception_e); +/* + * Checks if cpl <= required_cpl; if true, return true. Otherwise queue + * a #GP and return false. + */ +bool kvm_require_cpl(struct kvm_vcpu *vcpu, int required_cpl) +{ + if (kvm_x86_ops->get_cpl(vcpu) <= required_cpl) + return true; + kvm_queue_exception_e(vcpu, GP_VECTOR, 0); + return false; +} +EXPORT_SYMBOL_GPL(kvm_require_cpl); + /* * Load the pae pdptrs. Return true is they are all valid. */ -- cgit v1.2.3