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, 111 insertions, 0 deletions

diff --git a/Documentation/trace/index.rst b/Documentation/trace/index.rst
new file mode 100644
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+================================
+Linux Tracing Technologies Guide
+================================
+
+Tracing in the Linux kernel is a powerful mechanism that allows
+developers and system administrators to analyze and debug system
+behavior. This guide provides documentation on various tracing
+frameworks and tools available in the Linux kernel.
+
+Introduction to Tracing
+-----------------------
+
+This section provides an overview of Linux tracing mechanisms
+and debugging approaches.
+
+.. toctree::
+   :maxdepth: 1
+
+   debugging
+   tracepoints
+   tracepoint-analysis
+   ring-buffer-map
+
+Core Tracing Frameworks
+-----------------------
+
+The following are the primary tracing frameworks integrated into
+the Linux kernel.
+
+.. toctree::
+   :maxdepth: 1
+
+   ftrace
+   ftrace-design
+   ftrace-uses
+   kprobes
+   kprobetrace
+   fprobetrace
+   eprobetrace
+   fprobe
+   ring-buffer-design
+
+Event Tracing and Analysis
+--------------------------
+
+A detailed explanation of event tracing mechanisms and their
+applications.
+
+.. toctree::
+   :maxdepth: 1
+
+   events
+   events-kmem
+   events-power
+   events-nmi
+   events-msr
+   events-landlock
+   events-pci
+   events-pci-controller
+   boottime-trace
+   histogram
+   histogram-design
+
+Hardware and Performance Tracing
+--------------------------------
+
+This section covers tracing features that monitor hardware
+interactions and system performance.
+
+.. toctree::
+   :maxdepth: 1
+
+   intel_th
+   stm
+   sys-t
+   coresight/index
+   rv/index
+   hisi-ptt
+   mmiotrace
+   hwlat_detector
+   osnoise-tracer
+   timerlat-tracer
+
+User-Space Tracing
+------------------
+
+These tools allow tracing user-space applications and
+interactions.
+
+.. toctree::
+   :maxdepth: 1
+
+   user_events
+   uprobetracer
+
+Remote Tracing
+--------------
+
+This section covers the framework to read compatible ring-buffers, written by
+entities outside of the kernel (most likely firmware or hypervisor)
+
+.. toctree::
+   :maxdepth: 1
+
+   remotes
+
+Additional Resources
+--------------------
+
+For more details, refer to the respective documentation of each
+tracing tool and framework.