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, 87 insertions, 0 deletions

diff --git a/sound/hda/codecs/ca0110.c b/sound/hda/codecs/ca0110.c
new file mode 100644
index 000000000..d17fc3878
--- /dev/null
+++ b/sound/hda/codecs/ca0110.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * HD audio codec driver for Creative X-Fi CA0110-IBG chip
+ *
+ * Copyright (c) 2008 Takashi Iwai <tiwai@suse.de>
+ */
+
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <sound/core.h>
+#include <sound/hda_codec.h>
+#include "hda_local.h"
+#include "hda_auto_parser.h"
+#include "hda_jack.h"
+#include "generic.h"
+
+static int ca0110_parse_auto_config(struct hda_codec *codec)
+{
+	struct hda_gen_spec *spec = codec->spec;
+	int err;
+
+	err = snd_hda_parse_pin_defcfg(codec, &spec->autocfg, NULL, 0);
+	if (err < 0)
+		return err;
+	err = snd_hda_gen_parse_auto_config(codec, &spec->autocfg);
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
+static int ca0110_probe(struct hda_codec *codec, const struct hda_device_id *id)
+{
+	struct hda_gen_spec *spec;
+	int err;
+
+	spec = kzalloc_obj(*spec);
+	if (!spec)
+		return -ENOMEM;
+	snd_hda_gen_spec_init(spec);
+	codec->spec = spec;
+
+	spec->multi_cap_vol = 1;
+	codec->bus->core.needs_damn_long_delay = 1;
+
+	err = ca0110_parse_auto_config(codec);
+	if (err < 0)
+		goto error;
+
+	return 0;
+
+ error:
+	snd_hda_gen_remove(codec);
+	return err;
+}
+
+
+static const struct hda_codec_ops ca0110_codec_ops = {
+	.probe = ca0110_probe,
+	.remove = snd_hda_gen_remove,
+	.build_controls = snd_hda_gen_build_controls,
+	.build_pcms = snd_hda_gen_build_pcms,
+	.init = snd_hda_gen_init,
+	.unsol_event = snd_hda_jack_unsol_event,
+};
+
+/*
+ * driver entries
+ */
+static const struct hda_device_id snd_hda_id_ca0110[] = {
+	HDA_CODEC_ID(0x1102000a, "CA0110-IBG"),
+	HDA_CODEC_ID(0x1102000b, "CA0110-IBG"),
+	HDA_CODEC_ID(0x1102000d, "SB0880 X-Fi"),
+	{} /* terminator */
+};
+MODULE_DEVICE_TABLE(hdaudio, snd_hda_id_ca0110);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Creative CA0110-IBG HD-audio codec");
+
+static struct hda_codec_driver ca0110_driver = {
+	.id = snd_hda_id_ca0110,
+	.ops = &ca0110_codec_ops,
+};
+
+module_hda_codec_driver(ca0110_driver);