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, 276 insertions, 0 deletions

diff --git a/sound/firewire/fireface/ff-stream.c b/sound/firewire/fireface/ff-stream.c
new file mode 100644
index 000000000..ba42490f2
--- /dev/null
+++ b/sound/firewire/fireface/ff-stream.c
@@ -0,0 +1,276 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ff-stream.c - a part of driver for RME Fireface series
+ *
+ * Copyright (c) 2015-2017 Takashi Sakamoto
+ */
+
+#include "ff.h"
+
+#define READY_TIMEOUT_MS	200
+
+int snd_ff_stream_get_multiplier_mode(enum cip_sfc sfc,
+				      enum snd_ff_stream_mode *mode)
+{
+	static const enum snd_ff_stream_mode modes[] = {
+		[CIP_SFC_32000] = SND_FF_STREAM_MODE_LOW,
+		[CIP_SFC_44100] = SND_FF_STREAM_MODE_LOW,
+		[CIP_SFC_48000] = SND_FF_STREAM_MODE_LOW,
+		[CIP_SFC_88200] = SND_FF_STREAM_MODE_MID,
+		[CIP_SFC_96000] = SND_FF_STREAM_MODE_MID,
+		[CIP_SFC_176400] = SND_FF_STREAM_MODE_HIGH,
+		[CIP_SFC_192000] = SND_FF_STREAM_MODE_HIGH,
+	};
+
+	if (sfc >= CIP_SFC_COUNT)
+		return -EINVAL;
+
+	*mode = modes[sfc];
+
+	return 0;
+}
+
+static inline void finish_session(struct snd_ff *ff)
+{
+	ff->spec->protocol->finish_session(ff);
+	ff->spec->protocol->switch_fetching_mode(ff, false);
+}
+
+static int init_stream(struct snd_ff *ff, struct amdtp_stream *s)
+{
+	struct fw_iso_resources *resources;
+	enum amdtp_stream_direction dir;
+	int err;
+
+	if (s == &ff->tx_stream) {
+		resources = &ff->tx_resources;
+		dir = AMDTP_IN_STREAM;
+	} else {
+		resources = &ff->rx_resources;
+		dir = AMDTP_OUT_STREAM;
+	}
+
+	err = fw_iso_resources_init(resources, ff->unit);
+	if (err < 0)
+		return err;
+
+	err = amdtp_ff_init(s, ff->unit, dir);
+	if (err < 0)
+		fw_iso_resources_destroy(resources);
+
+	return err;
+}
+
+static void destroy_stream(struct snd_ff *ff, struct amdtp_stream *s)
+{
+	amdtp_stream_destroy(s);
+
+	if (s == &ff->tx_stream)
+		fw_iso_resources_destroy(&ff->tx_resources);
+	else
+		fw_iso_resources_destroy(&ff->rx_resources);
+}
+
+int snd_ff_stream_init_duplex(struct snd_ff *ff)
+{
+	int err;
+
+	err = init_stream(ff, &ff->rx_stream);
+	if (err < 0)
+		return err;
+
+	err = init_stream(ff, &ff->tx_stream);
+	if (err < 0) {
+		destroy_stream(ff, &ff->rx_stream);
+		return err;
+	}
+
+	err = amdtp_domain_init(&ff->domain);
+	if (err < 0) {
+		destroy_stream(ff, &ff->rx_stream);
+		destroy_stream(ff, &ff->tx_stream);
+	}
+
+	return err;
+}
+
+/*
+ * This function should be called before starting streams or after stopping
+ * streams.
+ */
+void snd_ff_stream_destroy_duplex(struct snd_ff *ff)
+{
+	amdtp_domain_destroy(&ff->domain);
+
+	destroy_stream(ff, &ff->rx_stream);
+	destroy_stream(ff, &ff->tx_stream);
+}
+
+int snd_ff_stream_reserve_duplex(struct snd_ff *ff, unsigned int rate,
+				 unsigned int frames_per_period,
+				 unsigned int frames_per_buffer)
+{
+	unsigned int curr_rate;
+	enum snd_ff_clock_src src;
+	int err;
+
+	err = ff->spec->protocol->get_clock(ff, &curr_rate, &src);
+	if (err < 0)
+		return err;
+
+	if (ff->substreams_counter == 0 || curr_rate != rate) {
+		enum snd_ff_stream_mode mode;
+		int i;
+
+		amdtp_domain_stop(&ff->domain);
+		finish_session(ff);
+
+		fw_iso_resources_free(&ff->tx_resources);
+		fw_iso_resources_free(&ff->rx_resources);
+
+		for (i = 0; i < CIP_SFC_COUNT; ++i) {
+			if (amdtp_rate_table[i] == rate)
+				break;
+		}
+		if (i >= CIP_SFC_COUNT)
+			return -EINVAL;
+
+		err = snd_ff_stream_get_multiplier_mode(i, &mode);
+		if (err < 0)
+			return err;
+
+		err = amdtp_ff_set_parameters(&ff->tx_stream, rate,
+					ff->spec->pcm_capture_channels[mode]);
+		if (err < 0)
+			return err;
+
+		err = amdtp_ff_set_parameters(&ff->rx_stream, rate,
+					ff->spec->pcm_playback_channels[mode]);
+		if (err < 0)
+			return err;
+
+		err = ff->spec->protocol->allocate_resources(ff, rate);
+		if (err < 0)
+			return err;
+
+		err = amdtp_domain_set_events_per_period(&ff->domain,
+					frames_per_period, frames_per_buffer);
+		if (err < 0) {
+			fw_iso_resources_free(&ff->tx_resources);
+			fw_iso_resources_free(&ff->rx_resources);
+			return err;
+		}
+	}
+
+	return 0;
+}
+
+int snd_ff_stream_start_duplex(struct snd_ff *ff, unsigned int rate)
+{
+	int err;
+
+	if (ff->substreams_counter == 0)
+		return 0;
+
+	if (amdtp_streaming_error(&ff->tx_stream) ||
+	    amdtp_streaming_error(&ff->rx_stream)) {
+		amdtp_domain_stop(&ff->domain);
+		finish_session(ff);
+	}
+
+	/*
+	 * Regardless of current source of clock signal, drivers transfer some
+	 * packets. Then, the device transfers packets.
+	 */
+	if (!amdtp_stream_running(&ff->rx_stream)) {
+		int spd = fw_parent_device(ff->unit)->max_speed;
+
+		err = ff->spec->protocol->begin_session(ff, rate);
+		if (err < 0)
+			goto error;
+
+		err = amdtp_domain_add_stream(&ff->domain, &ff->rx_stream,
+					      ff->rx_resources.channel, spd);
+		if (err < 0)
+			goto error;
+
+		err = amdtp_domain_add_stream(&ff->domain, &ff->tx_stream,
+					      ff->tx_resources.channel, spd);
+		if (err < 0)
+			goto error;
+
+		// NOTE: The device doesn't transfer packets unless receiving any packet. The
+		// sequence of tx packets includes cycle skip corresponding to empty packet or
+		// NODATA packet in IEC 61883-1/6. The sequence of the number of data blocks per
+		// packet is important for media clock recovery.
+		err = amdtp_domain_start(&ff->domain, 0, true, true);
+		if (err < 0)
+			goto error;
+
+		if (!amdtp_domain_wait_ready(&ff->domain, READY_TIMEOUT_MS)) {
+			err = -ETIMEDOUT;
+			goto error;
+		}
+
+		err = ff->spec->protocol->switch_fetching_mode(ff, true);
+		if (err < 0)
+			goto error;
+	}
+
+	return 0;
+error:
+	amdtp_domain_stop(&ff->domain);
+	finish_session(ff);
+
+	return err;
+}
+
+void snd_ff_stream_stop_duplex(struct snd_ff *ff)
+{
+	if (ff->substreams_counter == 0) {
+		amdtp_domain_stop(&ff->domain);
+		finish_session(ff);
+
+		fw_iso_resources_free(&ff->tx_resources);
+		fw_iso_resources_free(&ff->rx_resources);
+	}
+}
+
+void snd_ff_stream_update_duplex(struct snd_ff *ff)
+{
+	amdtp_domain_stop(&ff->domain);
+
+	// The device discontinue to transfer packets.
+	amdtp_stream_pcm_abort(&ff->tx_stream);
+	amdtp_stream_pcm_abort(&ff->rx_stream);
+}
+
+void snd_ff_stream_lock_changed(struct snd_ff *ff)
+{
+	ff->dev_lock_changed = true;
+	wake_up(&ff->hwdep_wait);
+}
+
+int snd_ff_stream_lock_try(struct snd_ff *ff)
+{
+	guard(spinlock_irq)(&ff->lock);
+
+	/* user land lock this */
+	if (ff->dev_lock_count < 0)
+		return -EBUSY;
+
+	/* this is the first time */
+	if (ff->dev_lock_count++ == 0)
+		snd_ff_stream_lock_changed(ff);
+	return 0;
+}
+
+void snd_ff_stream_lock_release(struct snd_ff *ff)
+{
+	guard(spinlock_irq)(&ff->lock);
+
+	if (WARN_ON(ff->dev_lock_count <= 0))
+		return;
+	if (--ff->dev_lock_count == 0)
+		snd_ff_stream_lock_changed(ff);
+}