CVE-2026-64555: KVM: arm64: nv: Fix SPSR_EL2 restore in kvm_hyp_handle_mops()

From: Greg Kroah-Hartman <[email protected]>

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

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

KVM: arm64: nv: Fix SPSR_EL2 restore in kvm_hyp_handle_mops()

kvm_hyp_handle_mops() resets the single-step state machine as part of
rewinding state for a MOPS exception by modifying vcpu_cpsr() and
writing the result directly into hardware.

In the case of nested virtualization, vcpu_cpsr() is a synthetic value
such that the rest of KVM can deal with vEL2 cleanly. That means the
value requires translation before being written into hardware, which is
unfortunately missing from the MOPS handler.

Fix it by directly modifying SPSR_EL2 and avoiding the synthetic state
altogether, which will be resynchronized on the next 'full' exit back
to KVM.

The Linux kernel CVE team has assigned CVE-2026-64555 to this issue.


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

	Issue introduced in 6.7 with commit 2de451a329cf662beeba71f63c7f83ee24ca6642 and fixed in 6.12.97 with commit 10a568010e827108d149779908850afaec898846
	Issue introduced in 6.7 with commit 2de451a329cf662beeba71f63c7f83ee24ca6642 and fixed in 6.18.40 with commit 884b44256041ec6b2dcbe8e6a67384d26145cba1
	Issue introduced in 6.7 with commit 2de451a329cf662beeba71f63c7f83ee24ca6642 and fixed in 7.1.5 with commit dd3b237eb7780d65eae296d3d3a70012b6e7a02f
	Issue introduced in 6.7 with commit 2de451a329cf662beeba71f63c7f83ee24ca6642 and fixed in 7.2-rc4 with commit ff1022c3de46753eb7eba2f6efd990569e66ff95

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-2026-64555
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/arm64/kvm/hyp/include/hyp/switch.h


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/10a568010e827108d149779908850afaec898846
	https://git.kernel.org/stable/c/884b44256041ec6b2dcbe8e6a67384d26145cba1
	https://git.kernel.org/stable/c/dd3b237eb7780d65eae296d3d3a70012b6e7a02f
	https://git.kernel.org/stable/c/ff1022c3de46753eb7eba2f6efd990569e66ff95