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, 153 insertions, 0 deletions

diff --git a/sound/soc/codecs/ac97.c b/sound/soc/codecs/ac97.c
new file mode 100644
index 000000000..d8444a083
--- /dev/null
+++ b/sound/soc/codecs/ac97.c
@@ -0,0 +1,153 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * ac97.c  --  ALSA Soc AC97 codec support
+ *
+ * Copyright 2005 Wolfson Microelectronics PLC.
+ * Author: Liam Girdwood <lrg@slimlogic.co.uk>
+ *
+ * Generic AC97 support.
+ */
+
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/ac97_codec.h>
+#include <sound/initval.h>
+#include <sound/soc.h>
+
+static const struct snd_soc_dapm_widget ac97_widgets[] = {
+	SND_SOC_DAPM_INPUT("RX"),
+	SND_SOC_DAPM_OUTPUT("TX"),
+};
+
+static const struct snd_soc_dapm_route ac97_routes[] = {
+	{ "AC97 Capture", NULL, "RX" },
+	{ "TX", NULL, "AC97 Playback" },
+};
+
+static int ac97_prepare(struct snd_pcm_substream *substream,
+			struct snd_soc_dai *dai)
+{
+	struct snd_soc_component *component = dai->component;
+	struct snd_ac97 *ac97 = snd_soc_component_get_drvdata(component);
+
+	int reg = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) ?
+		  AC97_PCM_FRONT_DAC_RATE : AC97_PCM_LR_ADC_RATE;
+	return snd_ac97_set_rate(ac97, reg, substream->runtime->rate);
+}
+
+static const struct snd_soc_dai_ops ac97_dai_ops = {
+	.prepare	= ac97_prepare,
+};
+
+static struct snd_soc_dai_driver ac97_dai = {
+	.name = "ac97-hifi",
+	.playback = {
+		.stream_name = "AC97 Playback",
+		.channels_min = 1,
+		.channels_max = 2,
+		.rates = SNDRV_PCM_RATE_KNOT,
+		.formats = SND_SOC_STD_AC97_FMTS,},
+	.capture = {
+		.stream_name = "AC97 Capture",
+		.channels_min = 1,
+		.channels_max = 2,
+		.rates = SNDRV_PCM_RATE_KNOT,
+		.formats = SND_SOC_STD_AC97_FMTS,},
+	.ops = &ac97_dai_ops,
+};
+
+static int ac97_soc_probe(struct snd_soc_component *component)
+{
+	struct snd_ac97 *ac97;
+	struct snd_ac97_bus *ac97_bus;
+	struct snd_ac97_template ac97_template;
+	int ret;
+
+	/* add codec as bus device for standard ac97 */
+	ret = snd_ac97_bus(component->card->snd_card, 0, soc_ac97_ops,
+			   NULL, &ac97_bus);
+	if (ret < 0)
+		return ret;
+
+	memset(&ac97_template, 0, sizeof(struct snd_ac97_template));
+	ret = snd_ac97_mixer(ac97_bus, &ac97_template, &ac97);
+	if (ret < 0)
+		return ret;
+
+	snd_soc_component_set_drvdata(component, ac97);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int ac97_soc_suspend(struct snd_soc_component *component)
+{
+	struct snd_ac97 *ac97 = snd_soc_component_get_drvdata(component);
+
+	snd_ac97_suspend(ac97);
+
+	return 0;
+}
+
+static int ac97_soc_resume(struct snd_soc_component *component)
+{
+
+	struct snd_ac97 *ac97 = snd_soc_component_get_drvdata(component);
+
+	snd_ac97_resume(ac97);
+
+	return 0;
+}
+#else
+#define ac97_soc_suspend NULL
+#define ac97_soc_resume NULL
+#endif
+
+static const struct snd_soc_component_driver soc_component_dev_ac97 = {
+	.probe			= ac97_soc_probe,
+	.suspend		= ac97_soc_suspend,
+	.resume			= ac97_soc_resume,
+	.dapm_widgets		= ac97_widgets,
+	.num_dapm_widgets	= ARRAY_SIZE(ac97_widgets),
+	.dapm_routes		= ac97_routes,
+	.num_dapm_routes	= ARRAY_SIZE(ac97_routes),
+	.idle_bias_on		= 1,
+	.use_pmdown_time	= 1,
+	.endianness		= 1,
+};
+
+static int ac97_probe(struct platform_device *pdev)
+{
+	return devm_snd_soc_register_component(&pdev->dev,
+			&soc_component_dev_ac97, &ac97_dai, 1);
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id ac97_codec_of_match[] = {
+	{ .compatible = "realtek,alc203", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ac97_codec_of_match);
+#endif
+
+static struct platform_driver ac97_codec_driver = {
+	.driver = {
+		.name = "ac97-codec",
+		.of_match_table = of_match_ptr(ac97_codec_of_match),
+	},
+
+	.probe = ac97_probe,
+};
+
+module_platform_driver(ac97_codec_driver);
+
+MODULE_DESCRIPTION("Soc Generic AC97 driver");
+MODULE_AUTHOR("Liam Girdwood");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:ac97-codec");