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, 270 insertions, 0 deletions

diff --git a/sound/ppc/beep.c b/sound/ppc/beep.c
new file mode 100644
index 000000000..1b03a7961
--- /dev/null
+++ b/sound/ppc/beep.c
@@ -0,0 +1,270 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Beep using pcm
+ *
+ * Copyright (c) by Takashi Iwai <tiwai@suse.de>
+ */
+
+#include <linux/io.h>
+#include <asm/irq.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/input.h>
+#include <linux/pci.h>
+#include <linux/dma-mapping.h>
+#include <sound/core.h>
+#include <sound/control.h>
+#include "pmac.h"
+
+struct pmac_beep {
+	int running;		/* boolean */
+	int volume;		/* mixer volume: 0-100 */
+	int volume_play;	/* currently playing volume */
+	int hz;
+	int nsamples;
+	short *buf;		/* allocated wave buffer */
+	dma_addr_t addr;	/* physical address of buffer */
+	struct input_dev *dev;
+};
+
+/*
+ * stop beep if running
+ */
+void snd_pmac_beep_stop(struct snd_pmac *chip)
+{
+	struct pmac_beep *beep = chip->beep;
+	if (beep && beep->running) {
+		beep->running = 0;
+		snd_pmac_beep_dma_stop(chip);
+	}
+}
+
+/*
+ * Stuff for outputting a beep.  The values range from -327 to +327
+ * so we can multiply by an amplitude in the range 0..100 to get a
+ * signed short value to put in the output buffer.
+ */
+static const short beep_wform[256] = {
+	0,	40,	79,	117,	153,	187,	218,	245,
+	269,	288,	304,	316,	323,	327,	327,	324,
+	318,	310,	299,	288,	275,	262,	249,	236,
+	224,	213,	204,	196,	190,	186,	183,	182,
+	182,	183,	186,	189,	192,	196,	200,	203,
+	206,	208,	209,	209,	209,	207,	204,	201,
+	197,	193,	188,	183,	179,	174,	170,	166,
+	163,	161,	160,	159,	159,	160,	161,	162,
+	164,	166,	168,	169,	171,	171,	171,	170,
+	169,	167,	163,	159,	155,	150,	144,	139,
+	133,	128,	122,	117,	113,	110,	107,	105,
+	103,	103,	103,	103,	104,	104,	105,	105,
+	105,	103,	101,	97,	92,	86,	78,	68,
+	58,	45,	32,	18,	3,	-11,	-26,	-41,
+	-55,	-68,	-79,	-88,	-95,	-100,	-102,	-102,
+	-99,	-93,	-85,	-75,	-62,	-48,	-33,	-16,
+	0,	16,	33,	48,	62,	75,	85,	93,
+	99,	102,	102,	100,	95,	88,	79,	68,
+	55,	41,	26,	11,	-3,	-18,	-32,	-45,
+	-58,	-68,	-78,	-86,	-92,	-97,	-101,	-103,
+	-105,	-105,	-105,	-104,	-104,	-103,	-103,	-103,
+	-103,	-105,	-107,	-110,	-113,	-117,	-122,	-128,
+	-133,	-139,	-144,	-150,	-155,	-159,	-163,	-167,
+	-169,	-170,	-171,	-171,	-171,	-169,	-168,	-166,
+	-164,	-162,	-161,	-160,	-159,	-159,	-160,	-161,
+	-163,	-166,	-170,	-174,	-179,	-183,	-188,	-193,
+	-197,	-201,	-204,	-207,	-209,	-209,	-209,	-208,
+	-206,	-203,	-200,	-196,	-192,	-189,	-186,	-183,
+	-182,	-182,	-183,	-186,	-190,	-196,	-204,	-213,
+	-224,	-236,	-249,	-262,	-275,	-288,	-299,	-310,
+	-318,	-324,	-327,	-327,	-323,	-316,	-304,	-288,
+	-269,	-245,	-218,	-187,	-153,	-117,	-79,	-40,
+};
+
+#define BEEP_SRATE	22050	/* 22050 Hz sample rate */
+#define BEEP_BUFLEN	512
+#define BEEP_VOLUME	15	/* 0 - 100 */
+
+static int snd_pmac_beep_event(struct input_dev *dev, unsigned int type,
+			       unsigned int code, int hz)
+{
+	struct snd_pmac *chip;
+	struct pmac_beep *beep;
+	int beep_speed = 0;
+	int srate;
+	int period, ncycles, nsamples;
+	int i, j, f;
+	short *p;
+
+	if (type != EV_SND)
+		return -1;
+
+	switch (code) {
+	case SND_BELL: if (hz) hz = 1000; break;
+	case SND_TONE: break;
+	default: return -1;
+	}
+
+	chip = input_get_drvdata(dev);
+	if (!chip)
+		return -1;
+	beep = chip->beep;
+	if (!beep)
+		return -1;
+
+	if (! hz) {
+		guard(spinlock_irqsave)(&chip->reg_lock);
+		if (beep->running)
+			snd_pmac_beep_stop(chip);
+		return 0;
+	}
+
+	beep_speed = snd_pmac_rate_index(chip, &chip->playback, BEEP_SRATE);
+	srate = chip->freq_table[beep_speed];
+
+	if (hz <= srate / BEEP_BUFLEN || hz > srate / 2)
+		hz = 1000;
+
+	scoped_guard(spinlock_irqsave, &chip->reg_lock) {
+		if (chip->playback.running || chip->capture.running || beep->running)
+			return 0;
+		beep->running = 1;
+	}
+
+	if (hz == beep->hz && beep->volume == beep->volume_play) {
+		nsamples = beep->nsamples;
+	} else {
+		period = srate * 256 / hz;	/* fixed point */
+		ncycles = BEEP_BUFLEN * 256 / period;
+		nsamples = (period * ncycles) >> 8;
+		f = ncycles * 65536 / nsamples;
+		j = 0;
+		p = beep->buf;
+		for (i = 0; i < nsamples; ++i, p += 2) {
+			p[0] = p[1] = beep_wform[j >> 8] * beep->volume;
+			j = (j + f) & 0xffff;
+		}
+		beep->hz = hz;
+		beep->volume_play = beep->volume;
+		beep->nsamples = nsamples;
+	}
+
+	guard(spinlock_irqsave)(&chip->reg_lock);
+	snd_pmac_beep_dma_start(chip, beep->nsamples * 4, beep->addr, beep_speed);
+	return 0;
+}
+
+/*
+ * beep volume mixer
+ */
+
+static int snd_pmac_info_beep(struct snd_kcontrol *kcontrol,
+			      struct snd_ctl_elem_info *uinfo)
+{
+	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
+	uinfo->count = 1;
+	uinfo->value.integer.min = 0;
+	uinfo->value.integer.max = 100;
+	return 0;
+}
+
+static int snd_pmac_get_beep(struct snd_kcontrol *kcontrol,
+			     struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_pmac *chip = snd_kcontrol_chip(kcontrol);
+	if (snd_BUG_ON(!chip->beep))
+		return -ENXIO;
+	ucontrol->value.integer.value[0] = chip->beep->volume;
+	return 0;
+}
+
+static int snd_pmac_put_beep(struct snd_kcontrol *kcontrol,
+			     struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_pmac *chip = snd_kcontrol_chip(kcontrol);
+	unsigned int oval, nval;
+	if (snd_BUG_ON(!chip->beep))
+		return -ENXIO;
+	oval = chip->beep->volume;
+	nval = ucontrol->value.integer.value[0];
+	if (nval > 100)
+		return -EINVAL;
+	chip->beep->volume = nval;
+	return oval != chip->beep->volume;
+}
+
+static const struct snd_kcontrol_new snd_pmac_beep_mixer = {
+	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
+	.name = "Beep Playback Volume",
+	.info = snd_pmac_info_beep,
+	.get = snd_pmac_get_beep,
+	.put = snd_pmac_put_beep,
+};
+
+/* Initialize beep stuff */
+int snd_pmac_attach_beep(struct snd_pmac *chip)
+{
+	struct pmac_beep *beep;
+	struct input_dev *input_dev;
+	struct snd_kcontrol *beep_ctl;
+	void *dmabuf;
+	int err = -ENOMEM;
+
+	beep = kzalloc_obj(*beep);
+	if (! beep)
+		return -ENOMEM;
+	dmabuf = dma_alloc_coherent(&chip->pdev->dev, BEEP_BUFLEN * 4,
+				    &beep->addr, GFP_KERNEL);
+	input_dev = input_allocate_device();
+	if (! dmabuf || ! input_dev)
+		goto fail1;
+
+	/* FIXME: set more better values */
+	input_dev->name = "PowerMac Beep";
+	input_dev->phys = "powermac/beep";
+	input_dev->id.bustype = BUS_ADB;
+	input_dev->id.vendor = 0x001f;
+	input_dev->id.product = 0x0001;
+	input_dev->id.version = 0x0100;
+
+	input_dev->evbit[0] = BIT_MASK(EV_SND);
+	input_dev->sndbit[0] = BIT_MASK(SND_BELL) | BIT_MASK(SND_TONE);
+	input_dev->event = snd_pmac_beep_event;
+	input_dev->dev.parent = &chip->pdev->dev;
+	input_set_drvdata(input_dev, chip);
+
+	beep->dev = input_dev;
+	beep->buf = dmabuf;
+	beep->volume = BEEP_VOLUME;
+	beep->running = 0;
+
+	beep_ctl = snd_ctl_new1(&snd_pmac_beep_mixer, chip);
+	err = snd_ctl_add(chip->card, beep_ctl);
+	if (err < 0)
+		goto fail1;
+
+	chip->beep = beep;
+
+	err = input_register_device(beep->dev);
+	if (err)
+		goto fail2;
+ 
+ 	return 0;
+ 
+ fail2:	snd_ctl_remove(chip->card, beep_ctl);
+ fail1:	input_free_device(input_dev);
+	if (dmabuf)
+		dma_free_coherent(&chip->pdev->dev, BEEP_BUFLEN * 4,
+				  dmabuf, beep->addr);
+	kfree(beep);
+	return err;
+}
+
+void snd_pmac_detach_beep(struct snd_pmac *chip)
+{
+	if (chip->beep) {
+		input_unregister_device(chip->beep->dev);
+		dma_free_coherent(&chip->pdev->dev, BEEP_BUFLEN * 4,
+				  chip->beep->buf, chip->beep->addr);
+		kfree(chip->beep);
+		chip->beep = NULL;
+	}
+}