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, 442 insertions, 0 deletions

diff --git a/drivers/mfd/ipaq-micro.c b/drivers/mfd/ipaq-micro.c
new file mode 100644
index 000000000..5146a6eb0
--- /dev/null
+++ b/drivers/mfd/ipaq-micro.c
@@ -0,0 +1,442 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Compaq iPAQ h3xxx Atmel microcontroller companion support
+ *
+ * This is an Atmel AT90LS8535 with a special flashed-in firmware that
+ * implements the special protocol used by this driver.
+ *
+ * based on previous kernel 2.4 version by Andrew Christian
+ * Author : Alessandro Gardich <gremlin@gremlin.it>
+ * Author : Dmitry Artamonow <mad_soft@inbox.ru>
+ * Author : Linus Walleij <linus.walleij@linaro.org>
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/pm.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/ipaq-micro.h>
+#include <linux/string.h>
+#include <linux/string_choices.h>
+#include <linux/random.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+
+#include <mach/hardware.h>
+
+static void ipaq_micro_trigger_tx(struct ipaq_micro *micro)
+{
+	struct ipaq_micro_txdev *tx = &micro->tx;
+	struct ipaq_micro_msg *msg = micro->msg;
+	int i, bp;
+	u8 checksum;
+	u32 val;
+
+	bp = 0;
+	tx->buf[bp++] = CHAR_SOF;
+
+	checksum = ((msg->id & 0x0f) << 4) | (msg->tx_len & 0x0f);
+	tx->buf[bp++] = checksum;
+
+	for (i = 0; i < msg->tx_len; i++) {
+		tx->buf[bp++] = msg->tx_data[i];
+		checksum += msg->tx_data[i];
+	}
+
+	tx->buf[bp++] = checksum;
+	tx->len = bp;
+	tx->index = 0;
+
+	/* Enable interrupt */
+	val = readl(micro->base + UTCR3);
+	val |= UTCR3_TIE;
+	writel(val, micro->base + UTCR3);
+}
+
+int ipaq_micro_tx_msg(struct ipaq_micro *micro, struct ipaq_micro_msg *msg)
+{
+	unsigned long flags;
+
+	dev_dbg(micro->dev, "TX msg: %02x, %d bytes\n", msg->id, msg->tx_len);
+
+	spin_lock_irqsave(&micro->lock, flags);
+	if (micro->msg) {
+		list_add_tail(&msg->node, &micro->queue);
+		spin_unlock_irqrestore(&micro->lock, flags);
+		return 0;
+	}
+	micro->msg = msg;
+	ipaq_micro_trigger_tx(micro);
+	spin_unlock_irqrestore(&micro->lock, flags);
+	return 0;
+}
+EXPORT_SYMBOL(ipaq_micro_tx_msg);
+
+static void micro_rx_msg(struct ipaq_micro *micro, u8 id, int len, u8 *data)
+{
+	dev_dbg(micro->dev, "RX msg: %02x, %d bytes\n", id, len);
+
+	spin_lock(&micro->lock);
+	switch (id) {
+	case MSG_VERSION:
+	case MSG_EEPROM_READ:
+	case MSG_EEPROM_WRITE:
+	case MSG_BACKLIGHT:
+	case MSG_NOTIFY_LED:
+	case MSG_THERMAL_SENSOR:
+	case MSG_BATTERY:
+		/* Handle synchronous messages */
+		if (micro->msg && micro->msg->id == id) {
+			struct ipaq_micro_msg *msg = micro->msg;
+
+			memcpy(msg->rx_data, data, len);
+			msg->rx_len = len;
+			complete(&micro->msg->ack);
+			if (!list_empty(&micro->queue)) {
+				micro->msg = list_entry(micro->queue.next,
+							struct ipaq_micro_msg,
+							node);
+				list_del_init(&micro->msg->node);
+				ipaq_micro_trigger_tx(micro);
+			} else
+				micro->msg = NULL;
+			dev_dbg(micro->dev, "OK RX message 0x%02x\n", id);
+		} else {
+			dev_err(micro->dev,
+				"out of band RX message 0x%02x\n", id);
+			if (!micro->msg)
+				dev_info(micro->dev, "no message queued\n");
+			else
+				dev_info(micro->dev, "expected message %02x\n",
+					 micro->msg->id);
+		}
+		break;
+	case MSG_KEYBOARD:
+		if (micro->key)
+			micro->key(micro->key_data, len, data);
+		else
+			dev_dbg(micro->dev, "key message ignored, no handle\n");
+		break;
+	case MSG_TOUCHSCREEN:
+		if (micro->ts)
+			micro->ts(micro->ts_data, len, data);
+		else
+			dev_dbg(micro->dev, "touchscreen message ignored, no handle\n");
+		break;
+	default:
+		dev_err(micro->dev,
+			"unknown msg %d [%d] %*ph\n", id, len, len, data);
+		break;
+	}
+	spin_unlock(&micro->lock);
+}
+
+static void micro_process_char(struct ipaq_micro *micro, u8 ch)
+{
+	struct ipaq_micro_rxdev *rx = &micro->rx;
+
+	switch (rx->state) {
+	case STATE_SOF:	/* Looking for SOF */
+		if (ch == CHAR_SOF)
+			rx->state = STATE_ID; /* Next byte is the id and len */
+		break;
+	case STATE_ID: /* Looking for id and len byte */
+		rx->id = (ch & 0xf0) >> 4;
+		rx->len = (ch & 0x0f);
+		rx->index = 0;
+		rx->chksum = ch;
+		rx->state = (rx->len > 0) ? STATE_DATA : STATE_CHKSUM;
+		break;
+	case STATE_DATA: /* Looking for 'len' data bytes */
+		rx->chksum += ch;
+		rx->buf[rx->index] = ch;
+		if (++rx->index == rx->len)
+			rx->state = STATE_CHKSUM;
+		break;
+	case STATE_CHKSUM: /* Looking for the checksum */
+		if (ch == rx->chksum)
+			micro_rx_msg(micro, rx->id, rx->len, rx->buf);
+		rx->state = STATE_SOF;
+		break;
+	}
+}
+
+static void micro_rx_chars(struct ipaq_micro *micro)
+{
+	u32 status, ch;
+
+	while ((status = readl(micro->base + UTSR1)) & UTSR1_RNE) {
+		ch = readl(micro->base + UTDR);
+		if (status & UTSR1_PRE)
+			dev_err(micro->dev, "rx: parity error\n");
+		else if (status & UTSR1_FRE)
+			dev_err(micro->dev, "rx: framing error\n");
+		else if (status & UTSR1_ROR)
+			dev_err(micro->dev, "rx: overrun error\n");
+		micro_process_char(micro, ch);
+	}
+}
+
+static void ipaq_micro_get_version(struct ipaq_micro *micro)
+{
+	struct ipaq_micro_msg msg = {
+		.id = MSG_VERSION,
+	};
+
+	ipaq_micro_tx_msg_sync(micro, &msg);
+	if (msg.rx_len == 4) {
+		memcpy(micro->version, msg.rx_data, 4);
+		micro->version[4] = '\0';
+	} else if (msg.rx_len == 9) {
+		memcpy(micro->version, msg.rx_data, 4);
+		micro->version[4] = '\0';
+		/* Bytes 4-7 are "pack", byte 8 is "boot type" */
+	} else {
+		dev_err(micro->dev,
+			"illegal version message %d bytes\n", msg.rx_len);
+	}
+}
+
+static void ipaq_micro_eeprom_read(struct ipaq_micro *micro,
+				   u8 address, u8 len, u8 *data)
+{
+	struct ipaq_micro_msg msg = {
+		.id = MSG_EEPROM_READ,
+	};
+	u8 i;
+
+	for (i = 0; i < len; i++) {
+		msg.tx_data[0] = address + i;
+		msg.tx_data[1] = 1;
+		msg.tx_len = 2;
+		ipaq_micro_tx_msg_sync(micro, &msg);
+		memcpy(data + (i * 2), msg.rx_data, 2);
+	}
+}
+
+static char *ipaq_micro_str(u8 *wchar, u8 len)
+{
+	char retstr[256] = { 0 };
+	u8 i;
+
+	for (i = 0; i < len / 2; i++)
+		retstr[i] = wchar[i * 2];
+	return kstrdup(retstr, GFP_KERNEL);
+}
+
+static u16 ipaq_micro_to_u16(u8 *data)
+{
+	return data[1] << 8 | data[0];
+}
+
+static void __init ipaq_micro_eeprom_dump(struct ipaq_micro *micro)
+{
+	u8 dump[256];
+	char *str;
+
+	ipaq_micro_eeprom_read(micro, 0, 128, dump);
+	str = ipaq_micro_str(dump, 10);
+	if (str) {
+		dev_info(micro->dev, "HW version %s\n", str);
+		kfree(str);
+	}
+	str = ipaq_micro_str(dump+10, 40);
+	if (str) {
+		dev_info(micro->dev, "serial number: %s\n", str);
+		/* Feed the random pool with this */
+		add_device_randomness(str, strlen(str));
+		kfree(str);
+	}
+	str = ipaq_micro_str(dump+50, 20);
+	if (str) {
+		dev_info(micro->dev, "module ID: %s\n", str);
+		kfree(str);
+	}
+	str = ipaq_micro_str(dump+70, 10);
+	if (str) {
+		dev_info(micro->dev, "product revision: %s\n", str);
+		kfree(str);
+	}
+	dev_info(micro->dev, "product ID: %u\n", ipaq_micro_to_u16(dump+80));
+	dev_info(micro->dev, "frame rate: %u fps\n",
+		 ipaq_micro_to_u16(dump+82));
+	dev_info(micro->dev, "page mode: %u\n", ipaq_micro_to_u16(dump+84));
+	dev_info(micro->dev, "country ID: %u\n", ipaq_micro_to_u16(dump+86));
+	dev_info(micro->dev, "color display: %s\n",
+		 str_yes_no(ipaq_micro_to_u16(dump + 88)));
+	dev_info(micro->dev, "ROM size: %u MiB\n", ipaq_micro_to_u16(dump+90));
+	dev_info(micro->dev, "RAM size: %u KiB\n", ipaq_micro_to_u16(dump+92));
+	dev_info(micro->dev, "screen: %u x %u\n",
+		 ipaq_micro_to_u16(dump+94), ipaq_micro_to_u16(dump+96));
+}
+
+static void micro_tx_chars(struct ipaq_micro *micro)
+{
+	struct ipaq_micro_txdev *tx = &micro->tx;
+	u32 val;
+
+	while ((tx->index < tx->len) &&
+	       (readl(micro->base + UTSR1) & UTSR1_TNF)) {
+		writel(tx->buf[tx->index], micro->base + UTDR);
+		tx->index++;
+	}
+
+	/* Stop interrupts */
+	val = readl(micro->base + UTCR3);
+	val &= ~UTCR3_TIE;
+	writel(val, micro->base + UTCR3);
+}
+
+static void micro_reset_comm(struct ipaq_micro *micro)
+{
+	struct ipaq_micro_rxdev *rx = &micro->rx;
+	u32 val;
+
+	if (micro->msg)
+		complete(&micro->msg->ack);
+
+	/* Initialize Serial channel protocol frame */
+	rx->state = STATE_SOF;  /* Reset the state machine */
+
+	/* Set up interrupts */
+	writel(0x01, micro->sdlc + 0x0); /* Select UART mode */
+
+	/* Clean up CR3 */
+	writel(0x0, micro->base + UTCR3);
+
+	/* Format: 8N1 */
+	writel(UTCR0_8BitData | UTCR0_1StpBit, micro->base + UTCR0);
+
+	/* Baud rate: 115200 */
+	writel(0x0, micro->base + UTCR1);
+	writel(0x1, micro->base + UTCR2);
+
+	/* Clear SR0 */
+	writel(0xff, micro->base + UTSR0);
+
+	/* Enable RX int, disable TX int */
+	writel(UTCR3_TXE | UTCR3_RXE | UTCR3_RIE, micro->base + UTCR3);
+	val = readl(micro->base + UTCR3);
+	val &= ~UTCR3_TIE;
+	writel(val, micro->base + UTCR3);
+}
+
+static irqreturn_t micro_serial_isr(int irq, void *dev_id)
+{
+	struct ipaq_micro *micro = dev_id;
+	struct ipaq_micro_txdev *tx = &micro->tx;
+	u32 status;
+
+	status = readl(micro->base + UTSR0);
+	do {
+		if (status & (UTSR0_RID | UTSR0_RFS)) {
+			if (status & UTSR0_RID)
+				/* Clear the Receiver IDLE bit */
+				writel(UTSR0_RID, micro->base + UTSR0);
+			micro_rx_chars(micro);
+		}
+
+		/* Clear break bits */
+		if (status & (UTSR0_RBB | UTSR0_REB))
+			writel(status & (UTSR0_RBB | UTSR0_REB),
+			       micro->base + UTSR0);
+
+		if (status & UTSR0_TFS)
+			micro_tx_chars(micro);
+
+		status = readl(micro->base + UTSR0);
+
+	} while (((tx->index < tx->len) && (status & UTSR0_TFS)) ||
+		 (status & (UTSR0_RFS | UTSR0_RID)));
+
+	return IRQ_HANDLED;
+}
+
+static const struct mfd_cell micro_cells[] = {
+	{ .name = "ipaq-micro-backlight", },
+	{ .name = "ipaq-micro-battery", },
+	{ .name = "ipaq-micro-keys", },
+	{ .name = "ipaq-micro-ts", },
+	{ .name = "ipaq-micro-leds", },
+};
+
+static int __maybe_unused micro_resume(struct device *dev)
+{
+	struct ipaq_micro *micro = dev_get_drvdata(dev);
+
+	micro_reset_comm(micro);
+	mdelay(10);
+
+	return 0;
+}
+
+static int __init micro_probe(struct platform_device *pdev)
+{
+	struct ipaq_micro *micro;
+	int ret;
+	int irq;
+
+	micro = devm_kzalloc(&pdev->dev, sizeof(*micro), GFP_KERNEL);
+	if (!micro)
+		return -ENOMEM;
+
+	micro->dev = &pdev->dev;
+
+	micro->base = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
+	if (IS_ERR(micro->base))
+		return PTR_ERR(micro->base);
+
+	micro->sdlc = devm_platform_ioremap_resource(pdev, 1);
+	if (IS_ERR(micro->sdlc))
+		return PTR_ERR(micro->sdlc);
+
+	micro_reset_comm(micro);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return -EINVAL;
+	ret = devm_request_irq(&pdev->dev, irq, micro_serial_isr,
+			       IRQF_SHARED, "ipaq-micro",
+			       micro);
+	if (ret) {
+		dev_err(&pdev->dev, "unable to grab serial port IRQ\n");
+		return ret;
+	} else
+		dev_info(&pdev->dev, "grabbed serial port IRQ\n");
+
+	spin_lock_init(&micro->lock);
+	INIT_LIST_HEAD(&micro->queue);
+	platform_set_drvdata(pdev, micro);
+
+	ret = mfd_add_devices(&pdev->dev, pdev->id, micro_cells,
+			      ARRAY_SIZE(micro_cells), NULL, 0, NULL);
+	if (ret) {
+		dev_err(&pdev->dev, "error adding MFD cells");
+		return ret;
+	}
+
+	/* Check version */
+	ipaq_micro_get_version(micro);
+	dev_info(&pdev->dev, "Atmel micro ASIC version %s\n", micro->version);
+	ipaq_micro_eeprom_dump(micro);
+
+	return 0;
+}
+
+static const struct dev_pm_ops micro_dev_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(NULL, micro_resume)
+};
+
+static struct platform_driver micro_device_driver = {
+	.driver   = {
+		.name	= "ipaq-h3xxx-micro",
+		.pm	= &micro_dev_pm_ops,
+		.suppress_bind_attrs = true,
+	},
+};
+builtin_platform_driver_probe(micro_device_driver, micro_probe);