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, 33 insertions, 0 deletions

diff --git a/Documentation/driver-api/iio/intro.rst b/Documentation/driver-api/iio/intro.rst
new file mode 100644
index 000000000..3653fbd57
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+++ b/Documentation/driver-api/iio/intro.rst
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+.. include:: <isonum.txt>
+
+============
+Introduction
+============
+
+The main purpose of the Industrial I/O subsystem (IIO) is to provide support
+for devices that in some sense perform either
+analog-to-digital conversion (ADC) or digital-to-analog conversion (DAC)
+or both. The aim is to fill the gap between the somewhat similar hwmon and
+:doc:`input <../input>` subsystems. Hwmon is directed at low sample rate
+sensors used to monitor and control the system itself, like fan speed control
+or temperature measurement. :doc:`Input <../input>` is, as its name suggests,
+focused on human interaction input devices (keyboard, mouse, touchscreen).
+In some cases there is considerable overlap between these and IIO.
+
+Devices that fall into this category include:
+
+* analog to digital converters (ADCs)
+* accelerometers
+* capacitance to digital converters (CDCs)
+* digital to analog converters (DACs)
+* gyroscopes
+* inertial measurement units (IMUs)
+* color and light sensors
+* magnetometers
+* pressure sensors
+* proximity sensors
+* temperature sensors
+
+Usually these sensors are connected via :doc:`SPI <../spi>` or
+:doc:`I2C <../i2c>`. A common use case of the sensors devices is to have
+combined functionality (e.g. light plus proximity sensor).