KVM is a full virtualization solution for Linux on AMD64 and Intel 64 systems. KVM is a Linux kernel module built for the standard Red Hat Enterprise Linux kernel. The kvm_emulate_hypercall implementation was missing a check for the Current Privilege Level . A local, unprivileged user in a virtual machine could use this flaw to cause a local denial of service or escalate their privileges within that virtual machine. This update also fixes the following bugs: * non-maskable interrupts were not supported on systems with AMD processors. As a consequence, Windows Server 2008 R2 guests running with more than one virtual CPU assigned on systems with AMD processors would hang at the Windows shut down screen when a restart was attempted. This update adds support for NMI filtering on systems with AMD processors, allowing clean restarts of Windows Server 2008 R2 guests running with multiple virtual CPUs. * significant performance issues for guests running 64-bit editions of Windows. This update improves performance for guests running 64-bit editions of Windows. * Windows guests may have experienced time drift. * removing the Red Hat VirtIO Ethernet Adapter from a guest running Windows Server 2008 R2 caused KVM to crash. With this update, device removal should not cause this issue. All KVM users should upgrade to these updated packages, which contain backported patches to resolve these issues. Note: The procedure in the Solution section must be performed before this update takes effect.