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, 277 insertions, 0 deletions

diff --git a/sound/ppc/daca.c b/sound/ppc/daca.c
new file mode 100644
index 000000000..f35cb870d
--- /dev/null
+++ b/sound/ppc/daca.c
@@ -0,0 +1,277 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * PMac DACA lowlevel functions
+ *
+ * Copyright (c) by Takashi Iwai <tiwai@suse.de>
+ */
+
+
+#include <linux/init.h>
+#include <linux/i2c.h>
+#include <linux/kmod.h>
+#include <linux/slab.h>
+#include <sound/core.h>
+#include "pmac.h"
+
+/* i2c address */
+#define DACA_I2C_ADDR	0x4d
+
+/* registers */
+#define DACA_REG_SR	0x01
+#define DACA_REG_AVOL	0x02
+#define DACA_REG_GCFG	0x03
+
+/* maximum volume value */
+#define DACA_VOL_MAX	0x38
+
+
+struct pmac_daca {
+	struct pmac_keywest i2c;
+	int left_vol, right_vol;
+	unsigned int deemphasis : 1;
+	unsigned int amp_on : 1;
+};
+
+
+/*
+ * initialize / detect DACA
+ */
+static int daca_init_client(struct pmac_keywest *i2c)
+{
+	unsigned short wdata = 0x00;
+	/* SR: no swap, 1bit delay, 32-48kHz */
+	/* GCFG: power amp inverted, DAC on */
+	if (i2c_smbus_write_byte_data(i2c->client, DACA_REG_SR, 0x08) < 0 ||
+	    i2c_smbus_write_byte_data(i2c->client, DACA_REG_GCFG, 0x05) < 0)
+		return -EINVAL;
+	return i2c_smbus_write_block_data(i2c->client, DACA_REG_AVOL,
+					  2, (unsigned char*)&wdata);
+}
+
+/*
+ * update volume
+ */
+static int daca_set_volume(struct pmac_daca *mix)
+{
+	unsigned char data[2];
+  
+	if (! mix->i2c.client)
+		return -ENODEV;
+  
+	if (mix->left_vol > DACA_VOL_MAX)
+		data[0] = DACA_VOL_MAX;
+	else
+		data[0] = mix->left_vol;
+	if (mix->right_vol > DACA_VOL_MAX)
+		data[1] = DACA_VOL_MAX;
+	else
+		data[1] = mix->right_vol;
+	data[1] |= mix->deemphasis ? 0x40 : 0;
+	if (i2c_smbus_write_block_data(mix->i2c.client, DACA_REG_AVOL,
+				       2, data) < 0) {
+		dev_err(&mix->i2c.client->dev, "failed to set volume\n");
+		return -EINVAL;
+	}
+	return 0;
+}
+
+
+/* deemphasis switch */
+#define daca_info_deemphasis		snd_ctl_boolean_mono_info
+
+static int daca_get_deemphasis(struct snd_kcontrol *kcontrol,
+			       struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_pmac *chip = snd_kcontrol_chip(kcontrol);
+	struct pmac_daca *mix;
+	mix = chip->mixer_data;
+	if (!mix)
+		return -ENODEV;
+	ucontrol->value.integer.value[0] = mix->deemphasis ? 1 : 0;
+	return 0;
+}
+
+static int daca_put_deemphasis(struct snd_kcontrol *kcontrol,
+			       struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_pmac *chip = snd_kcontrol_chip(kcontrol);
+	struct pmac_daca *mix;
+	int change;
+
+	mix = chip->mixer_data;
+	if (!mix)
+		return -ENODEV;
+	change = mix->deemphasis != ucontrol->value.integer.value[0];
+	if (change) {
+		mix->deemphasis = !!ucontrol->value.integer.value[0];
+		daca_set_volume(mix);
+	}
+	return change;
+}
+
+/* output volume */
+static int daca_info_volume(struct snd_kcontrol *kcontrol,
+			    struct snd_ctl_elem_info *uinfo)
+{
+	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
+	uinfo->count = 2;
+	uinfo->value.integer.min = 0;
+	uinfo->value.integer.max = DACA_VOL_MAX;
+	return 0;
+}
+
+static int daca_get_volume(struct snd_kcontrol *kcontrol,
+			   struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_pmac *chip = snd_kcontrol_chip(kcontrol);
+	struct pmac_daca *mix;
+	mix = chip->mixer_data;
+	if (!mix)
+		return -ENODEV;
+	ucontrol->value.integer.value[0] = mix->left_vol;
+	ucontrol->value.integer.value[1] = mix->right_vol;
+	return 0;
+}
+
+static int daca_put_volume(struct snd_kcontrol *kcontrol,
+			   struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_pmac *chip = snd_kcontrol_chip(kcontrol);
+	struct pmac_daca *mix;
+	unsigned int vol[2];
+	int change;
+
+	mix = chip->mixer_data;
+	if (!mix)
+		return -ENODEV;
+	vol[0] = ucontrol->value.integer.value[0];
+	vol[1] = ucontrol->value.integer.value[1];
+	if (vol[0] > DACA_VOL_MAX || vol[1] > DACA_VOL_MAX)
+		return -EINVAL;
+	change = mix->left_vol != vol[0] ||
+		mix->right_vol != vol[1];
+	if (change) {
+		mix->left_vol = vol[0];
+		mix->right_vol = vol[1];
+		daca_set_volume(mix);
+	}
+	return change;
+}
+
+/* amplifier switch */
+#define daca_info_amp	daca_info_deemphasis
+
+static int daca_get_amp(struct snd_kcontrol *kcontrol,
+			struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_pmac *chip = snd_kcontrol_chip(kcontrol);
+	struct pmac_daca *mix;
+	mix = chip->mixer_data;
+	if (!mix)
+		return -ENODEV;
+	ucontrol->value.integer.value[0] = mix->amp_on ? 1 : 0;
+	return 0;
+}
+
+static int daca_put_amp(struct snd_kcontrol *kcontrol,
+			struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_pmac *chip = snd_kcontrol_chip(kcontrol);
+	struct pmac_daca *mix;
+	int change;
+
+	mix = chip->mixer_data;
+	if (!mix)
+		return -ENODEV;
+	change = mix->amp_on != ucontrol->value.integer.value[0];
+	if (change) {
+		mix->amp_on = !!ucontrol->value.integer.value[0];
+		i2c_smbus_write_byte_data(mix->i2c.client, DACA_REG_GCFG,
+					  mix->amp_on ? 0x05 : 0x04);
+	}
+	return change;
+}
+
+static const struct snd_kcontrol_new daca_mixers[] = {
+	{ .iface = SNDRV_CTL_ELEM_IFACE_MIXER,
+	  .name = "Deemphasis Switch",
+	  .info = daca_info_deemphasis,
+	  .get = daca_get_deemphasis,
+	  .put = daca_put_deemphasis
+	},
+	{ .iface = SNDRV_CTL_ELEM_IFACE_MIXER,
+	  .name = "Master Playback Volume",
+	  .info = daca_info_volume,
+	  .get = daca_get_volume,
+	  .put = daca_put_volume
+	},
+	{ .iface = SNDRV_CTL_ELEM_IFACE_MIXER,
+	  .name = "Power Amplifier Switch",
+	  .info = daca_info_amp,
+	  .get = daca_get_amp,
+	  .put = daca_put_amp
+	},
+};
+
+
+#ifdef CONFIG_PM
+static void daca_resume(struct snd_pmac *chip)
+{
+	struct pmac_daca *mix = chip->mixer_data;
+	i2c_smbus_write_byte_data(mix->i2c.client, DACA_REG_SR, 0x08);
+	i2c_smbus_write_byte_data(mix->i2c.client, DACA_REG_GCFG,
+				  mix->amp_on ? 0x05 : 0x04);
+	daca_set_volume(mix);
+}
+#endif /* CONFIG_PM */
+
+
+static void daca_cleanup(struct snd_pmac *chip)
+{
+	struct pmac_daca *mix = chip->mixer_data;
+	if (! mix)
+		return;
+	snd_pmac_keywest_cleanup(&mix->i2c);
+	kfree(mix);
+	chip->mixer_data = NULL;
+}
+
+/* exported */
+int snd_pmac_daca_init(struct snd_pmac *chip)
+{
+	int i, err;
+	struct pmac_daca *mix;
+
+	request_module("i2c-powermac");
+
+	mix = kzalloc_obj(*mix);
+	if (! mix)
+		return -ENOMEM;
+	chip->mixer_data = mix;
+	chip->mixer_free = daca_cleanup;
+	mix->amp_on = 1; /* default on */
+
+	mix->i2c.addr = DACA_I2C_ADDR;
+	mix->i2c.init_client = daca_init_client;
+	mix->i2c.name = "DACA";
+	err = snd_pmac_keywest_init(&mix->i2c);
+	if (err < 0)
+		return err;
+
+	/*
+	 * build mixers
+	 */
+	strscpy(chip->card->mixername, "PowerMac DACA");
+
+	for (i = 0; i < ARRAY_SIZE(daca_mixers); i++) {
+		err = snd_ctl_add(chip->card, snd_ctl_new1(&daca_mixers[i], chip));
+		if (err < 0)
+			return err;
+	}
+
+#ifdef CONFIG_PM
+	chip->resume = daca_resume;
+#endif
+
+	return 0;
+}