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, 131 insertions, 0 deletions

diff --git a/sound/soc/sof/stream-ipc.c b/sound/soc/sof/stream-ipc.c
new file mode 100644
index 000000000..78758cf58
--- /dev/null
+++ b/sound/soc/sof/stream-ipc.c
@@ -0,0 +1,131 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause)
+//
+// This file is provided under a dual BSD/GPLv2 license.  When using or
+// redistributing this file, you may do so under either license.
+//
+// Copyright(c) 2019 Intel Corporation
+//
+// Authors: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
+
+/* Generic SOF IPC code */
+
+#include <linux/device.h>
+#include <linux/export.h>
+#include <linux/module.h>
+#include <linux/types.h>
+
+#include <sound/pcm.h>
+#include <sound/sof/stream.h>
+
+#include "ops.h"
+#include "sof-priv.h"
+#include "sof-audio.h"
+
+struct sof_stream {
+	size_t posn_offset;
+};
+
+/* Mailbox-based Generic IPC implementation */
+int sof_ipc_msg_data(struct snd_sof_dev *sdev,
+		     struct snd_sof_pcm_stream *sps,
+		     void *p, size_t sz)
+{
+	if (!sps || !sdev->stream_box.size) {
+		snd_sof_dsp_mailbox_read(sdev, sdev->dsp_box.offset, p, sz);
+	} else {
+		size_t posn_offset;
+
+		if (sps->substream) {
+			struct sof_stream *stream = sps->substream->runtime->private_data;
+
+			/* The stream might already be closed */
+			if (!stream)
+				return -ESTRPIPE;
+
+			posn_offset = stream->posn_offset;
+		} else if (sps->cstream) {
+
+			struct sof_compr_stream *sstream = sps->cstream->runtime->private_data;
+
+			if (!sstream)
+				return -ESTRPIPE;
+
+			posn_offset = sstream->posn_offset;
+
+		} else {
+			dev_err(sdev->dev, "%s: No stream opened\n", __func__);
+			return -EINVAL;
+		}
+
+		snd_sof_dsp_mailbox_read(sdev, posn_offset, p, sz);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(sof_ipc_msg_data);
+
+int sof_set_stream_data_offset(struct snd_sof_dev *sdev,
+			       struct snd_sof_pcm_stream *sps,
+			       size_t posn_offset)
+{
+	/* check if offset is overflow or it is not aligned */
+	if (posn_offset > sdev->stream_box.size ||
+	    posn_offset % sizeof(struct sof_ipc_stream_posn) != 0)
+		return -EINVAL;
+
+	posn_offset += sdev->stream_box.offset;
+
+	if (sps->substream) {
+		struct sof_stream *stream = sps->substream->runtime->private_data;
+
+		stream->posn_offset = posn_offset;
+		dev_dbg(sdev->dev, "pcm: stream dir %d, posn mailbox offset is %zu",
+			sps->substream->stream, posn_offset);
+	} else if (sps->cstream) {
+		struct sof_compr_stream *sstream = sps->cstream->runtime->private_data;
+
+		sstream->posn_offset = posn_offset;
+		dev_dbg(sdev->dev, "compr: stream dir %d, posn mailbox offset is %zu",
+			sps->cstream->direction, posn_offset);
+	} else {
+		dev_err(sdev->dev, "No stream opened");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(sof_set_stream_data_offset);
+
+int sof_stream_pcm_open(struct snd_sof_dev *sdev,
+			struct snd_pcm_substream *substream)
+{
+	struct sof_stream *stream = kmalloc_obj(*stream);
+
+	if (!stream)
+		return -ENOMEM;
+
+	/* binding pcm substream to hda stream */
+	substream->runtime->private_data = stream;
+
+	/* align to DMA minimum transfer size */
+	snd_pcm_hw_constraint_step(substream->runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_BYTES, 4);
+
+	/* avoid circular buffer wrap in middle of period */
+	snd_pcm_hw_constraint_integer(substream->runtime,
+				      SNDRV_PCM_HW_PARAM_PERIODS);
+
+	return 0;
+}
+EXPORT_SYMBOL(sof_stream_pcm_open);
+
+int sof_stream_pcm_close(struct snd_sof_dev *sdev,
+			 struct snd_pcm_substream *substream)
+{
+	struct sof_stream *stream = substream->runtime->private_data;
+
+	substream->runtime->private_data = NULL;
+	kfree(stream);
+
+	return 0;
+}
+EXPORT_SYMBOL(sof_stream_pcm_close);