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, 200 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/debugfs-hisi-hpre b/Documentation/ABI/testing/debugfs-hisi-hpre
new file mode 100644
index 000000000..5a137f701
--- /dev/null
+++ b/Documentation/ABI/testing/debugfs-hisi-hpre
@@ -0,0 +1,200 @@
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/cluster[0-3]/regs
+Date:		Sep 2019
+Contact:	linux-crypto@vger.kernel.org
+Description:	Dump debug registers from the HPRE cluster.
+		Only available for PF.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/cluster[0-3]/cluster_ctrl
+Date:		Sep 2019
+Contact:	linux-crypto@vger.kernel.org
+Description:	Write the HPRE core selection in the cluster into this file,
+		and then we can read the debug information of the core.
+		Only available for PF.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/rdclr_en
+Date:		Sep 2019
+Contact:	linux-crypto@vger.kernel.org
+Description:	HPRE cores debug registers read clear control. 1 means enable
+		register read clear, otherwise 0. Writing to this file has no
+		functional effect, only enable or disable counters clear after
+		reading of these registers.
+		Only available for PF.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/current_qm
+Date:		Sep 2019
+Contact:	linux-crypto@vger.kernel.org
+Description:	One HPRE controller has one PF and multiple VFs, each function
+		has a QM. Select the QM which below qm refers to.
+		Only available for PF.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/alg_qos
+Date:		Jun 2021
+Contact:	linux-crypto@vger.kernel.org
+Description:	The <bdf> is related the function for PF and VF.
+		HPRE driver supports to configure each function's QoS, the driver
+		supports to write <bdf> value to alg_qos in the host. Such as
+		"echo <bdf> value > alg_qos". The qos value is 1~1000, means
+		1/1000~1000/1000 of total QoS. The driver reading alg_qos to
+		get related QoS in the host and VM, Such as "cat alg_qos".
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/regs
+Date:		Sep 2019
+Contact:	linux-crypto@vger.kernel.org
+Description:	Dump debug registers from the HPRE.
+		Only available for PF.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/qm/regs
+Date:		Sep 2019
+Contact:	linux-crypto@vger.kernel.org
+Description:	Dump debug registers from the QM.
+		Available for PF and VF in host. VF in guest currently only
+		has one debug register.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/dev_usage
+Date:		Mar 2026
+Contact:	linux-crypto@vger.kernel.org
+Description:	Query the real-time bandwidth usage of device.
+		Returns the bandwidth usage of each channel on the device.
+		The returned number is in percentage.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/qm/current_q
+Date:		Sep 2019
+Contact:	linux-crypto@vger.kernel.org
+Description:	One QM may contain multiple queues. Select specific queue to
+		show its debug registers in above regs.
+		Only available for PF.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/qm/clear_enable
+Date:		Sep 2019
+Contact:	linux-crypto@vger.kernel.org
+Description:	QM debug registers(regs) read clear control. 1 means enable
+		register read clear, otherwise 0.
+		Writing to this file has no functional effect, only enable or
+		disable counters clear after reading of these registers.
+		Only available for PF.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/qm/err_irq
+Date:		Apr 2020
+Contact:	linux-crypto@vger.kernel.org
+Description:	Dump the number of invalid interrupts for
+		QM task completion.
+		Available for both PF and VF, and take no other effect on HPRE.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/qm/aeq_irq
+Date:		Apr 2020
+Contact:	linux-crypto@vger.kernel.org
+Description:	Dump the number of QM async event queue interrupts.
+		Available for both PF and VF, and take no other effect on HPRE.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/qm/abnormal_irq
+Date:		Apr 2020
+Contact:	linux-crypto@vger.kernel.org
+Description:	Dump the number of interrupts for QM abnormal event.
+		Available for both PF and VF, and take no other effect on HPRE.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/qm/create_qp_err
+Date:		Apr 2020
+Contact:	linux-crypto@vger.kernel.org
+Description:	Dump the number of queue allocation errors.
+		Available for both PF and VF, and take no other effect on HPRE.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/qm/mb_err
+Date:		Apr 2020
+Contact:	linux-crypto@vger.kernel.org
+Description:	Dump the number of failed QM mailbox commands.
+		Available for both PF and VF, and take no other effect on HPRE.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/qm/status
+Date:		Apr 2020
+Contact:	linux-crypto@vger.kernel.org
+Description:	Dump the status of the QM.
+		Two states: work, stop.
+		Available for both PF and VF, and take no other effect on HPRE.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/qm/diff_regs
+Date:		Mar 2022
+Contact:	linux-crypto@vger.kernel.org
+Description:	QM debug registers(regs) read hardware register value. This
+		node is used to show the change of the qm register values. This
+		node can be help users to check the change of register values.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/qm/qm_state
+Date:		Jan 2024
+Contact:	linux-crypto@vger.kernel.org
+Description:	Dump the state of the device.
+		0: busy, 1: idle.
+		Only available for PF, and take no other effect on HPRE.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/qm/dev_timeout
+Date:		Feb 2024
+Contact:	linux-crypto@vger.kernel.org
+Description:	Set the wait time when stop queue fails. Available for both PF
+		and VF, and take no other effect on HPRE.
+		0: not wait(default), others value: wait dev_timeout * 20 microsecond.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/qm/dev_state
+Date:		Feb 2024
+Contact:	linux-crypto@vger.kernel.org
+Description:	Dump the stop queue status of the QM. The default value is 0,
+		if dev_timeout is set, when stop queue fails, the dev_state
+		will return non-zero value. Available for both PF and VF,
+		and take no other effect on HPRE.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/hpre_dfx/diff_regs
+Date:		Mar 2022
+Contact:	linux-crypto@vger.kernel.org
+Description:	HPRE debug registers(regs) read hardware register value. This
+		node is used to show the change of the register values. This
+		node can be help users to check the change of register values.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/hpre_dfx/send_cnt
+Date:		Apr 2020
+Contact:	linux-crypto@vger.kernel.org
+Description:	Dump the total number of sent requests.
+		Available for both PF and VF, and take no other effect on HPRE.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/hpre_dfx/recv_cnt
+Date:		Apr 2020
+Contact:	linux-crypto@vger.kernel.org
+Description:	Dump the total number of received requests.
+		Available for both PF and VF, and take no other effect on HPRE.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/hpre_dfx/send_busy_cnt
+Date:		Apr 2020
+Contact:	linux-crypto@vger.kernel.org
+Description:	Dump the total number of requests sent
+		with returning busy.
+		Available for both PF and VF, and take no other effect on HPRE.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/hpre_dfx/send_fail_cnt
+Date:		Apr 2020
+Contact:	linux-crypto@vger.kernel.org
+Description:	Dump the total number of completed but error requests.
+		Available for both PF and VF, and take no other effect on HPRE.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/hpre_dfx/invalid_req_cnt
+Date:		Apr 2020
+Contact:	linux-crypto@vger.kernel.org
+Description:	Dump the total number of invalid requests being received.
+		Available for both PF and VF, and take no other effect on HPRE.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/hpre_dfx/overtime_thrhld
+Date:		Apr 2020
+Contact:	linux-crypto@vger.kernel.org
+Description:	Set the threshold time for counting the request which is
+		processed longer than the threshold.
+		0: disable(default), 1: 1 microsecond.
+		Available for both PF and VF, and take no other effect on HPRE.
+
+What:		/sys/kernel/debug/hisi_hpre/<bdf>/hpre_dfx/over_thrhld_cnt
+Date:		Apr 2020
+Contact:	linux-crypto@vger.kernel.org
+Description:	Dump the total number of time out requests.
+		Available for both PF and VF, and take no other effect on HPRE.
+
+What:           /sys/kernel/debug/hisi_hpre/<bdf>/cap_regs
+Date:           Oct 2024
+Contact:        linux-crypto@vger.kernel.org
+Description:    Dump the values of the qm and hpre capability bit registers and
+                support the query of device specifications to facilitate fault locating.
+                Available for both PF and VF, and take no other effect on HPRE.