KVM: SEV: Do cache maintenance on the source VM during intra-host migrationgrafted

Manually perform cache maintenance on the source VM during intra-host
migration to ensure no stale data is left in CPU caches after the VM is
destroyed.  Because the source VM is "converted" to a non-SEV VM, KVM's
memory reclaim flows won't trigger cache maintenance, e.g. when all guest
memory is reclaimed in response to detaching from the mmu_notifier.

Note, relying on the destination VM to do cache maintenance isn't an option
as KVM doesn't require identical guest memory configurations, i.e. the
source VM may have access to memory that the destination VM does not.
Enforcing equivalent memory configurations is infeasible, as it would
require a *deep* comparison of memslots, e.g. to verify that not only are
the memslot identical, but what the memslots point at is also identical.

Fixes: b56639318bb2 ("KVM: SEV: Add support for SEV intra host migration")
Cc: stable@vger.kernel.org
Reported-by: Stefan Teodorescu <fane@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20260923163721.1584779-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 163 insertions, 0 deletions

diff --git a/Documentation/process/kernel-enforcement-statement.rst b/Documentation/process/kernel-enforcement-statement.rst
new file mode 100644
index 000000000..dc2d813b2
--- /dev/null
+++ b/Documentation/process/kernel-enforcement-statement.rst
@@ -0,0 +1,163 @@
+.. _process_statement_kernel:
+
+Linux Kernel Enforcement Statement
+----------------------------------
+
+As developers of the Linux kernel, we have a keen interest in how our software
+is used and how the license for our software is enforced.  Compliance with the
+reciprocal sharing obligations of GPL-2.0 is critical to the long-term
+sustainability of our software and community.
+
+Although there is a right to enforce the separate copyright interests in the
+contributions made to our community, we share an interest in ensuring that
+individual enforcement actions are conducted in a manner that benefits our
+community and do not have an unintended negative impact on the health and
+growth of our software ecosystem.  In order to deter unhelpful enforcement
+actions, we agree that it is in the best interests of our development
+community to undertake the following commitment to users of the Linux kernel
+on behalf of ourselves and any successors to our copyright interests:
+
+    Notwithstanding the termination provisions of the GPL-2.0, we agree that
+    it is in the best interests of our development community to adopt the
+    following provisions of GPL-3.0 as additional permissions under our
+    license with respect to any non-defensive assertion of rights under the
+    license.
+
+	However, if you cease all violation of this License, then your license
+	from a particular copyright holder is reinstated (a) provisionally,
+	unless and until the copyright holder explicitly and finally
+	terminates your license, and (b) permanently, if the copyright holder
+	fails to notify you of the violation by some reasonable means prior to
+	60 days after the cessation.
+
+	Moreover, your license from a particular copyright holder is
+	reinstated permanently if the copyright holder notifies you of the
+	violation by some reasonable means, this is the first time you have
+	received notice of violation of this License (for any work) from that
+	copyright holder, and you cure the violation prior to 30 days after
+	your receipt of the notice.
+
+Our intent in providing these assurances is to encourage more use of the
+software.  We want companies and individuals to use, modify and distribute
+this software.  We want to work with users in an open and transparent way to
+eliminate any uncertainty about our expectations regarding compliance or
+enforcement that might limit adoption of our software.  We view legal action
+as a last resort, to be initiated only when other community efforts have
+failed to resolve the problem.
+
+Finally, once a non-compliance issue is resolved, we hope the user will feel
+welcome to join us in our efforts on this project.  Working together, we will
+be stronger.
+
+Except where noted below, we speak only for ourselves, and not for any company
+we might work for today, have in the past, or will in the future.
+
+  - Laura Abbott
+  - Bjorn Andersson (Linaro)
+  - Andrea Arcangeli
+  - Neil Armstrong
+  - Jens Axboe
+  - Pablo Neira Ayuso
+  - Khalid Aziz
+  - Ralf Baechle
+  - Felipe Balbi
+  - Arnd Bergmann
+  - Ard Biesheuvel
+  - Tim Bird
+  - Paolo Bonzini
+  - Christian Borntraeger
+  - Mark Brown (Linaro)
+  - Paul Burton
+  - Javier Martinez Canillas
+  - Rob Clark
+  - Kees Cook (Google)
+  - Jonathan Corbet
+  - Dennis Dalessandro
+  - Vivien Didelot (Savoir-faire Linux)
+  - Hans de Goede
+  - Mel Gorman (SUSE)
+  - Sven Eckelmann
+  - Alex Elder (Linaro)
+  - Fabio Estevam
+  - Larry Finger
+  - Bhumika Goyal
+  - Andy Gross
+  - Juergen Gross
+  - Shawn Guo
+  - Ulf Hansson
+  - Stephen Hemminger (Microsoft)
+  - Tejun Heo
+  - Rob Herring
+  - Masami Hiramatsu
+  - Michal Hocko
+  - Simon Horman
+  - Johan Hovold (Hovold Consulting AB)
+  - Christophe JAILLET
+  - Olof Johansson
+  - Lee Jones (Linaro)
+  - Heiner Kallweit
+  - Srinivas Kandagatla
+  - Jan Kara
+  - Shuah Khan (Samsung)
+  - David Kershner
+  - Jaegeuk Kim
+  - Namhyung Kim
+  - Colin Ian King
+  - Jeff Kirsher
+  - Greg Kroah-Hartman (Linux Foundation)
+  - Christian König
+  - Vinod Koul
+  - Krzysztof Kozlowski
+  - Viresh Kumar
+  - Aneesh Kumar K.V
+  - Julia Lawall
+  - Doug Ledford
+  - Chuck Lever (Oracle)
+  - Daniel Lezcano
+  - Shaohua Li
+  - Xin Long
+  - Tony Luck
+  - Catalin Marinas (Arm Ltd)
+  - Mike Marshall
+  - Chris Mason
+  - Paul E. McKenney
+  - Arnaldo Carvalho de Melo
+  - David S. Miller
+  - Ingo Molnar
+  - Kuninori Morimoto
+  - Trond Myklebust
+  - Martin K. Petersen (Oracle)
+  - Borislav Petkov
+  - Jiri Pirko
+  - Josh Poimboeuf
+  - Sebastian Reichel (Collabora)
+  - Guenter Roeck
+  - Joerg Roedel
+  - Leon Romanovsky
+  - Steven Rostedt (VMware)
+  - Frank Rowand
+  - Ivan Safonov
+  - Anna Schumaker
+  - Jes Sorensen
+  - K.Y. Srinivasan
+  - David Sterba (SUSE)
+  - Heiko Stuebner
+  - Jiri Kosina (SUSE)
+  - Willy Tarreau
+  - Dmitry Torokhov
+  - Linus Torvalds
+  - Thierry Reding
+  - Rik van Riel
+  - Luis R. Rodriguez
+  - Geert Uytterhoeven (Glider bvba)
+  - Eduardo Valentin (Amazon.com)
+  - Daniel Vetter
+  - Linus Walleij
+  - Richard Weinberger
+  - Dan Williams
+  - Rafael J. Wysocki
+  - Arvind Yadav
+  - Masahiro Yamada
+  - Wei Yongjun
+  - Lv Zheng
+  - Marc Zyngier (Arm Ltd)