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, 146 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-rtrs-client b/Documentation/ABI/testing/sysfs-class-rtrs-client
new file mode 100644
index 000000000..fecc59d1b
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-rtrs-client
@@ -0,0 +1,146 @@
+What:		/sys/class/rtrs-client
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	When a user of RTRS API creates a new session, a directory entry with
+		the name of that session is created under /sys/class/rtrs-client/<session-name>/
+
+What:		/sys/class/rtrs-client/<session-name>/add_path
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RW, adds a new path (connection) to an existing session. Expected format is the
+		following::
+
+		    <[source addr,]destination addr>
+		    *addr ::= [ ip:<ipv4|ipv6> | gid:<gid> ]
+
+What:		/sys/class/rtrs-client/<session-name>/max_reconnect_attempts
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Maximum number reconnect attempts the client should make before giving up
+		after connection breaks unexpectedly.
+
+What:		/sys/class/rtrs-client/<session-name>/mp_policy
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Multipath policy specifies which path should be selected on each IO:
+
+		round-robin (0):
+		    select path in per CPU round-robin manner.
+
+		min-inflight (1):
+		    select path with minimum inflights.
+
+		min-latency (2):
+		    select path with minimum latency.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Each path belonging to a given session is listed here by its source and
+		destination address. When a new path is added to a session by writing to
+		the "add_path" entry, a directory <src@dst> is created.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/state
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RO, Contains "connected" if the session is connected to the peer and fully
+		functional.  Otherwise the file contains "disconnected"
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/reconnect
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Write "1" to the file in order to reconnect the path.
+		Operation is blocking and returns 0 if reconnect was successful.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/disconnect
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Write "1" to the file in order to disconnect the path.
+		Operation blocks until RTRS path is disconnected.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/remove_path
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Write "1" to the file in order to disconnected and remove the path
+		from the session.  Operation blocks until the path is disconnected
+		and removed from the session.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/hca_name
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RO, Contains the name of HCA the connection established on.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/hca_port
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RO, Contains the port number of active port traffic is going through.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/src_addr
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RO, Contains the source address of the path
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/dst_addr
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RO, Contains the destination address of the path
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/cur_latency
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RO, Contains the latency time calculated by the heart-beat messages.
+		Whenever the client sends heart-beat message, it checks the time gap
+		between sending the heart-beat message and receiving the ACK.
+		This value can be changed regularly.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/stats/reset_all
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RW, Read will return usage help, write 0 will clear all the statistics.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/stats/cpu_migration
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RTRS expects that each HCA IRQ is pinned to a separate CPU. If it's
+		not the case, the processing of an I/O response could be processed on a
+		different CPU than where it was originally submitted.  This file shows
+		how many interrupts where generated on a non expected CPU.
+
+		"from:"
+		    is the CPU on which the IRQ was expected, but not generated.
+		"to:"
+		    is the CPU on which the IRQ was generated, but not expected.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/stats/reconnects
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Contains 2 unsigned int values, the first one records number of successful
+		reconnects in the path lifetime, the second one records number of failed
+		reconnects in the path lifetime.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/stats/rdma
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Contains statistics regarding rdma operations and inflight operations.
+		The output consists of 6 values::
+
+		    <read-count> <read-total-size> <write-count> \
+		    <write-total-size> <inflights> <failovered>