CVE-2026-89932: KVM: nVMX: Always flush vpid02 on first use

CVE-2026-89932: KVM: nVMX: Always flush vpid02 on first use

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

KVM: nVMX: Always flush vpid02 on first use

Make sure vpid02 is always flushed on first use by setting last_vpid=0
when allocating vpid02.  nested_vmx_transition_tlb_flush() will always
detect a VPID change on first VM-Enter after VMXON, because VPID=0 in
vmcs12 is not allowed if L1 enables VPID.

This avoids using stale TLB entries from a previous lifetime of the
VPID, that might have been associated with a different vCPU (or a
completely different VM).

Note that last_vpid is already being initialized as 0 when the vCPU is
created, but it is not reset when vpid02 is freed on VMXOFF. Hence, the
problem can only occur if L1 does VMXOFF -> VMXON, runs an L2, and KVM
happens to reuse a VPID that has TLB entries on the physical CPU.

The Linux kernel CVE team has assigned CVE-2026-89932 to this issue.


Affected and fixed versions
===========================

	Fixed in 5.15.221 with commit 26de0d2d9a8d14c03e5ebb25fd68b5bfcd5ac366
	Fixed in 6.1.188 with commit 8bc609999ec223089fec8d74c7de27d689606b36
	Fixed in 6.6.157 with commit 62604376c313178811375f40a282fc2a46cd2311
	Fixed in 6.12.110 with commit 8b98d662ab24f34710a56e03bc9169e4a5508606
	Fixed in 6.18.51 with commit 22dfcc22c95e91295119a1c3b469816ce44c4804
	Fixed in 7.2.5 with commit 121991d150735f3c0f7401678ce4d35c5b4ac898
	Fixed in 7.3-rc1 with commit f0772389413dce9657c7d6950abf3edbbd511356

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-89932
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	arch/x86/kvm/vmx/nested.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/26de0d2d9a8d14c03e5ebb25fd68b5bfcd5ac366
	https://git.kernel.org/stable/c/8bc609999ec223089fec8d74c7de27d689606b36
	https://git.kernel.org/stable/c/62604376c313178811375f40a282fc2a46cd2311
	https://git.kernel.org/stable/c/8b98d662ab24f34710a56e03bc9169e4a5508606
	https://git.kernel.org/stable/c/22dfcc22c95e91295119a1c3b469816ce44c4804
	https://git.kernel.org/stable/c/121991d150735f3c0f7401678ce4d35c5b4ac898
	https://git.kernel.org/stable/c/f0772389413dce9657c7d6950abf3edbbd511356