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, 215 insertions, 0 deletions

diff --git a/sound/soc/codecs/dmic.c b/sound/soc/codecs/dmic.c
new file mode 100644
index 000000000..cbed11136
--- /dev/null
+++ b/sound/soc/codecs/dmic.c
@@ -0,0 +1,215 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * dmic.c  --  SoC audio for Generic Digital MICs
+ *
+ * Author: Liam Girdwood <lrg@slimlogic.co.uk>
+ */
+
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/soc.h>
+#include <sound/soc-dapm.h>
+
+#define MAX_MODESWITCH_DELAY 70
+static int modeswitch_delay;
+module_param(modeswitch_delay, uint, 0644);
+
+static int wakeup_delay;
+module_param(wakeup_delay, uint, 0644);
+
+struct dmic {
+	struct gpio_desc *gpio_en;
+	struct regulator *vref;
+	int wakeup_delay;
+	/* Delay after DMIC mode switch */
+	int modeswitch_delay;
+};
+
+static int dmic_daiops_trigger(struct snd_pcm_substream *substream,
+			       int cmd, struct snd_soc_dai *dai)
+{
+	struct snd_soc_component *component = dai->component;
+	struct dmic *dmic = snd_soc_component_get_drvdata(component);
+
+	switch (cmd) {
+	case SNDRV_PCM_TRIGGER_STOP:
+		if (dmic->modeswitch_delay)
+			mdelay(dmic->modeswitch_delay);
+
+		break;
+	}
+
+	return 0;
+}
+
+static const struct snd_soc_dai_ops dmic_dai_ops = {
+	.trigger	= dmic_daiops_trigger,
+};
+
+static int dmic_aif_event(struct snd_soc_dapm_widget *w,
+			  struct snd_kcontrol *kcontrol, int event) {
+	struct snd_soc_component *component = snd_soc_dapm_to_component(w->dapm);
+	struct dmic *dmic = snd_soc_component_get_drvdata(component);
+	int ret = 0;
+
+	switch (event) {
+	case SND_SOC_DAPM_POST_PMU:
+		if (dmic->gpio_en)
+			gpiod_set_value_cansleep(dmic->gpio_en, 1);
+
+		if (dmic->vref) {
+			ret = regulator_enable(dmic->vref);
+			if (ret)
+				return ret;
+		}
+
+		if (dmic->wakeup_delay)
+			msleep(dmic->wakeup_delay);
+		break;
+	case SND_SOC_DAPM_POST_PMD:
+		if (dmic->gpio_en)
+			gpiod_set_value_cansleep(dmic->gpio_en, 0);
+
+		if (dmic->vref)
+			ret = regulator_disable(dmic->vref);
+
+		break;
+	}
+
+	return ret;
+}
+
+static struct snd_soc_dai_driver dmic_dai = {
+	.name = "dmic-hifi",
+	.capture = {
+		.stream_name = "Capture",
+		.channels_min = 1,
+		.channels_max = 8,
+		.rates = SNDRV_PCM_RATE_CONTINUOUS,
+		.formats = SNDRV_PCM_FMTBIT_S32_LE
+			| SNDRV_PCM_FMTBIT_S24_LE
+			| SNDRV_PCM_FMTBIT_S16_LE
+			| SNDRV_PCM_FMTBIT_DSD_U8
+			| SNDRV_PCM_FMTBIT_DSD_U16_LE
+			| SNDRV_PCM_FMTBIT_DSD_U32_LE
+			| SNDRV_PCM_FMTBIT_DSD_U16_BE
+			| SNDRV_PCM_FMTBIT_DSD_U32_BE,
+	},
+	.ops    = &dmic_dai_ops,
+};
+
+static int dmic_component_probe(struct snd_soc_component *component)
+{
+	struct dmic *dmic;
+
+	dmic = devm_kzalloc(component->dev, sizeof(*dmic), GFP_KERNEL);
+	if (!dmic)
+		return -ENOMEM;
+
+	dmic->vref = devm_regulator_get_optional(component->dev, "vref");
+	if (IS_ERR(dmic->vref)) {
+		if (PTR_ERR(dmic->vref) != -ENODEV)
+			return dev_err_probe(component->dev, PTR_ERR(dmic->vref),
+					     "Failed to get vref\n");
+		dmic->vref = NULL;
+	}
+
+	dmic->gpio_en = devm_gpiod_get_optional(component->dev,
+						"dmicen", GPIOD_OUT_LOW);
+	if (IS_ERR(dmic->gpio_en))
+		return PTR_ERR(dmic->gpio_en);
+
+	device_property_read_u32(component->dev, "wakeup-delay-ms",
+				 &dmic->wakeup_delay);
+	device_property_read_u32(component->dev, "modeswitch-delay-ms",
+				 &dmic->modeswitch_delay);
+	if (wakeup_delay)
+		dmic->wakeup_delay  = wakeup_delay;
+	if (modeswitch_delay)
+		dmic->modeswitch_delay  = modeswitch_delay;
+
+	if (dmic->modeswitch_delay > MAX_MODESWITCH_DELAY)
+		dmic->modeswitch_delay = MAX_MODESWITCH_DELAY;
+
+	snd_soc_component_set_drvdata(component, dmic);
+
+	return 0;
+}
+
+static const struct snd_soc_dapm_widget dmic_dapm_widgets[] = {
+	SND_SOC_DAPM_AIF_OUT_E("DMIC AIF", "Capture", 0,
+			       SND_SOC_NOPM, 0, 0, dmic_aif_event,
+			       SND_SOC_DAPM_POST_PMU | SND_SOC_DAPM_POST_PMD),
+	SND_SOC_DAPM_INPUT("DMic"),
+};
+
+static const struct snd_soc_dapm_route intercon[] = {
+	{"DMIC AIF", NULL, "DMic"},
+};
+
+static const struct snd_soc_component_driver soc_dmic = {
+	.probe			= dmic_component_probe,
+	.dapm_widgets		= dmic_dapm_widgets,
+	.num_dapm_widgets	= ARRAY_SIZE(dmic_dapm_widgets),
+	.dapm_routes		= intercon,
+	.num_dapm_routes	= ARRAY_SIZE(intercon),
+	.idle_bias_on		= 1,
+	.use_pmdown_time	= 1,
+	.endianness		= 1,
+};
+
+static int dmic_dev_probe(struct platform_device *pdev)
+{
+	int err;
+	u32 chans;
+	struct snd_soc_dai_driver *dai_drv = &dmic_dai;
+
+	if (pdev->dev.of_node) {
+		err = of_property_read_u32(pdev->dev.of_node, "num-channels", &chans);
+		if (err && (err != -EINVAL))
+			return err;
+
+		if (!err) {
+			if (chans < 1 || chans > 8)
+				return -EINVAL;
+
+			dai_drv = devm_kzalloc(&pdev->dev, sizeof(*dai_drv), GFP_KERNEL);
+			if (!dai_drv)
+				return -ENOMEM;
+
+			memcpy(dai_drv, &dmic_dai, sizeof(*dai_drv));
+			dai_drv->capture.channels_max = chans;
+		}
+	}
+
+	return devm_snd_soc_register_component(&pdev->dev,
+			&soc_dmic, dai_drv, 1);
+}
+
+MODULE_ALIAS("platform:dmic-codec");
+
+static const struct of_device_id dmic_dev_match[] = {
+	{.compatible = "dmic-codec"},
+	{}
+};
+MODULE_DEVICE_TABLE(of, dmic_dev_match);
+
+static struct platform_driver dmic_driver = {
+	.driver = {
+		.name = "dmic-codec",
+		.of_match_table = dmic_dev_match,
+	},
+	.probe = dmic_dev_probe,
+};
+
+module_platform_driver(dmic_driver);
+
+MODULE_DESCRIPTION("Generic DMIC driver");
+MODULE_AUTHOR("Liam Girdwood <lrg@slimlogic.co.uk>");
+MODULE_LICENSE("GPL");