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, 76 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-net-qmi b/Documentation/ABI/testing/sysfs-class-net-qmi
new file mode 100644
index 000000000..b028f5bc8
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-net-qmi
@@ -0,0 +1,76 @@
+What:		/sys/class/net/<iface>/qmi/raw_ip
+Date:		Dec 2015
+KernelVersion:	4.4
+Contact:	Bjørn Mork <bjorn@mork.no>
+Description:
+		Boolean.  Default: 'N'
+
+		Set this to 'Y' to change the network device link
+		framing from '802.3' to 'raw-ip'.
+
+		The netdev will change to reflect the link framing
+		mode.  The netdev is an ordinary ethernet device in
+		'802.3' mode, and the driver expects to exchange
+		frames with an ethernet header over the USB link. The
+		netdev is a headerless p-t-p device in 'raw-ip' mode,
+		and the driver expects to echange IPv4 or IPv6 packets
+		without any L2 header over the USB link.
+
+		Userspace is in full control of firmware configuration
+		through the delegation of the QMI protocol. Userspace
+		is responsible for coordination of driver and firmware
+		link framing mode, changing this setting to 'Y' if the
+		firmware is configured for 'raw-ip' mode.
+
+What:		/sys/class/net/<iface>/qmi/add_mux
+Date:		March 2017
+KernelVersion:	4.11
+Contact:	Bjørn Mork <bjorn@mork.no>
+Description:
+		Unsigned integer.
+
+		Write a number ranging from 1 to 254 to add a qmap mux
+		based network device, supported by recent Qualcomm based
+		modems.
+
+		The network device will be called qmimux.
+
+		Userspace is in charge of managing the qmux network device
+		activation and data stream setup on the modem side by
+		using the proper QMI protocol requests.
+
+What:		/sys/class/net/<iface>/qmi/del_mux
+Date:		March 2017
+KernelVersion:	4.11
+Contact:	Bjørn Mork <bjorn@mork.no>
+Description:
+		Unsigned integer.
+
+		Write a number ranging from 1 to 254 to delete a previously
+		created qmap mux based network device.
+
+What:		/sys/class/net/<qmimux iface>/qmap/mux_id
+Date:		January 2021
+KernelVersion:	5.12
+Contact:	Daniele Palmas <dnlplm@gmail.com>
+Description:
+		Unsigned integer
+
+		Indicates the mux id associated to the qmimux network interface
+		during its creation.
+
+What:		/sys/class/net/<iface>/qmi/pass_through
+Date:		January 2021
+KernelVersion:	5.12
+Contact:	Subash Abhinov Kasiviswanathan <quic_subashab@quicinc.com>
+Description:
+		Boolean.  Default: 'N'
+
+		Set this to 'Y' to enable 'pass-through' mode, allowing packets
+		in MAP format to be passed on to the stack.
+
+		Normally the rmnet driver (CONFIG_RMNET) is then used to process
+		and demultiplex these packets.
+
+		'Pass-through' mode can be enabled when the device is in
+		'raw-ip' mode only.