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, 190 insertions, 0 deletions

diff --git a/sound/ppc/powermac.c b/sound/ppc/powermac.c
new file mode 100644
index 000000000..e685d2458
--- /dev/null
+++ b/sound/ppc/powermac.c
@@ -0,0 +1,190 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Driver for PowerMac AWACS
+ * Copyright (c) 2001 by Takashi Iwai <tiwai@suse.de>
+ *   based on dmasound.c.
+ */
+
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/platform_device.h>
+#include <linux/module.h>
+#include <sound/core.h>
+#include <sound/initval.h>
+#include "pmac.h"
+#include "awacs.h"
+#include "burgundy.h"
+
+#define CHIP_NAME "PMac"
+
+MODULE_DESCRIPTION("PowerMac");
+MODULE_LICENSE("GPL");
+
+static int index = SNDRV_DEFAULT_IDX1;		/* Index 0-MAX */
+static char *id = SNDRV_DEFAULT_STR1;		/* ID for this card */
+static bool enable_beep = 1;
+
+module_param(index, int, 0444);
+MODULE_PARM_DESC(index, "Index value for " CHIP_NAME " soundchip.");
+module_param(id, charp, 0444);
+MODULE_PARM_DESC(id, "ID string for " CHIP_NAME " soundchip.");
+module_param(enable_beep, bool, 0444);
+MODULE_PARM_DESC(enable_beep, "Enable beep using PCM.");
+
+static struct platform_device *device;
+
+
+/*
+ */
+
+static int snd_pmac_probe(struct platform_device *devptr)
+{
+	struct snd_card *card;
+	struct snd_pmac *chip;
+	char *name_ext;
+	int err;
+
+	err = snd_card_new(&devptr->dev, index, id, THIS_MODULE, 0, &card);
+	if (err < 0)
+		return err;
+
+	err = snd_pmac_new(card, &chip);
+	if (err < 0)
+		goto __error;
+	card->private_data = chip;
+
+	switch (chip->model) {
+	case PMAC_BURGUNDY:
+		strscpy(card->driver, "PMac Burgundy");
+		strscpy(card->shortname, "PowerMac Burgundy");
+		sprintf(card->longname, "%s (Dev %d) Sub-frame %d",
+			card->shortname, chip->device_id, chip->subframe);
+		err = snd_pmac_burgundy_init(chip);
+		if (err < 0)
+			goto __error;
+		break;
+	case PMAC_DACA:
+		strscpy(card->driver, "PMac DACA");
+		strscpy(card->shortname, "PowerMac DACA");
+		sprintf(card->longname, "%s (Dev %d) Sub-frame %d",
+			card->shortname, chip->device_id, chip->subframe);
+		err = snd_pmac_daca_init(chip);
+		if (err < 0)
+			goto __error;
+		break;
+	case PMAC_TUMBLER:
+	case PMAC_SNAPPER:
+		name_ext = chip->model == PMAC_TUMBLER ? "Tumbler" : "Snapper";
+		sprintf(card->driver, "PMac %s", name_ext);
+		sprintf(card->shortname, "PowerMac %s", name_ext);
+		sprintf(card->longname, "%s (Dev %d) Sub-frame %d",
+			card->shortname, chip->device_id, chip->subframe);
+		err = snd_pmac_tumbler_init(chip);
+		if (err < 0)
+			goto __error;
+		err = snd_pmac_tumbler_post_init();
+		if (err < 0)
+			goto __error;
+		break;
+	case PMAC_AWACS:
+	case PMAC_SCREAMER:
+		name_ext = chip->model == PMAC_SCREAMER ? "Screamer" : "AWACS";
+		sprintf(card->driver, "PMac %s", name_ext);
+		sprintf(card->shortname, "PowerMac %s", name_ext);
+		if (chip->is_pbook_3400)
+			name_ext = " [PB3400]";
+		else if (chip->is_pbook_G3)
+			name_ext = " [PBG3]";
+		else
+			name_ext = "";
+		sprintf(card->longname, "%s%s Rev %d",
+			card->shortname, name_ext, chip->revision);
+		err = snd_pmac_awacs_init(chip);
+		if (err < 0)
+			goto __error;
+		break;
+	default:
+		dev_err(&devptr->dev, "unsupported hardware %d\n", chip->model);
+		err = -EINVAL;
+		goto __error;
+	}
+
+	err = snd_pmac_pcm_new(chip);
+	if (err < 0)
+		goto __error;
+
+	chip->initialized = 1;
+	if (enable_beep)
+		snd_pmac_attach_beep(chip);
+
+	err = snd_card_register(card);
+	if (err < 0)
+		goto __error;
+
+	platform_set_drvdata(devptr, card);
+	return 0;
+
+__error:
+	snd_card_free(card);
+	return err;
+}
+
+
+static void snd_pmac_remove(struct platform_device *devptr)
+{
+	snd_card_free(platform_get_drvdata(devptr));
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int snd_pmac_driver_suspend(struct device *dev)
+{
+	struct snd_card *card = dev_get_drvdata(dev);
+	snd_pmac_suspend(card->private_data);
+	return 0;
+}
+
+static int snd_pmac_driver_resume(struct device *dev)
+{
+	struct snd_card *card = dev_get_drvdata(dev);
+	snd_pmac_resume(card->private_data);
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(snd_pmac_pm, snd_pmac_driver_suspend, snd_pmac_driver_resume);
+#define SND_PMAC_PM_OPS	&snd_pmac_pm
+#else
+#define SND_PMAC_PM_OPS	NULL
+#endif
+
+#define SND_PMAC_DRIVER		"snd_powermac"
+
+static struct platform_driver snd_pmac_driver = {
+	.probe		= snd_pmac_probe,
+	.remove		= snd_pmac_remove,
+	.driver		= {
+		.name	= SND_PMAC_DRIVER,
+		.pm	= SND_PMAC_PM_OPS,
+	},
+};
+
+static int __init alsa_card_pmac_init(void)
+{
+	int err;
+
+	err = platform_driver_register(&snd_pmac_driver);
+	if (err < 0)
+		return err;
+	device = platform_device_register_simple(SND_PMAC_DRIVER, -1, NULL, 0);
+	return 0;
+
+}
+
+static void __exit alsa_card_pmac_exit(void)
+{
+	if (!IS_ERR(device))
+		platform_device_unregister(device);
+	platform_driver_unregister(&snd_pmac_driver);
+}
+
+module_init(alsa_card_pmac_init)
+module_exit(alsa_card_pmac_exit)