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, 414 insertions, 0 deletions

diff --git a/drivers/bluetooth/hci_serdev.c b/drivers/bluetooth/hci_serdev.c
new file mode 100644
index 000000000..d2eaf2f12
--- /dev/null
+++ b/drivers/bluetooth/hci_serdev.c
@@ -0,0 +1,414 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Bluetooth HCI serdev driver lib
+ *
+ *  Copyright (C) 2017  Linaro, Ltd., Rob Herring <robh@kernel.org>
+ *
+ *  Based on hci_ldisc.c:
+ *
+ *  Copyright (C) 2000-2001  Qualcomm Incorporated
+ *  Copyright (C) 2002-2003  Maxim Krasnyansky <maxk@qualcomm.com>
+ *  Copyright (C) 2004-2005  Marcel Holtmann <marcel@holtmann.org>
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/serdev.h>
+#include <linux/skbuff.h>
+
+#include <net/bluetooth/bluetooth.h>
+#include <net/bluetooth/hci_core.h>
+
+#include "hci_uart.h"
+
+static inline void hci_uart_tx_complete(struct hci_uart *hu, int pkt_type)
+{
+	struct hci_dev *hdev = hu->hdev;
+
+	/* Update HCI stat counters */
+	switch (pkt_type) {
+	case HCI_COMMAND_PKT:
+		hdev->stat.cmd_tx++;
+		break;
+
+	case HCI_ACLDATA_PKT:
+		hdev->stat.acl_tx++;
+		break;
+
+	case HCI_SCODATA_PKT:
+		hdev->stat.sco_tx++;
+		break;
+	}
+}
+
+static inline struct sk_buff *hci_uart_dequeue(struct hci_uart *hu)
+{
+	struct sk_buff *skb = hu->tx_skb;
+
+	if (!skb) {
+		if (test_bit(HCI_UART_PROTO_READY, &hu->flags))
+			skb = hu->proto->dequeue(hu);
+	} else
+		hu->tx_skb = NULL;
+
+	return skb;
+}
+
+static void hci_uart_write_work(struct work_struct *work)
+{
+	struct hci_uart *hu = container_of(work, struct hci_uart, write_work);
+	struct serdev_device *serdev = hu->serdev;
+	struct hci_dev *hdev = hu->hdev;
+	struct sk_buff *skb;
+
+	/* REVISIT:
+	 * should we cope with bad skbs or ->write() returning an error value?
+	 */
+	do {
+		clear_bit(HCI_UART_TX_WAKEUP, &hu->tx_state);
+
+		while ((skb = hci_uart_dequeue(hu))) {
+			int len;
+
+			len = serdev_device_write_buf(serdev,
+						      skb->data, skb->len);
+			hdev->stat.byte_tx += len;
+
+			skb_pull(skb, len);
+			if (skb->len) {
+				hu->tx_skb = skb;
+				break;
+			}
+
+			hci_uart_tx_complete(hu, hci_skb_pkt_type(skb));
+			kfree_skb(skb);
+		}
+
+		clear_bit(HCI_UART_SENDING, &hu->tx_state);
+	} while (test_bit(HCI_UART_TX_WAKEUP, &hu->tx_state));
+}
+
+/* ------- Interface to HCI layer ------ */
+
+/* Reset device */
+static int hci_uart_flush(struct hci_dev *hdev)
+{
+	struct hci_uart *hu  = hci_get_drvdata(hdev);
+
+	BT_DBG("hdev %p serdev %p", hdev, hu->serdev);
+
+	if (hu->tx_skb) {
+		kfree_skb(hu->tx_skb); hu->tx_skb = NULL;
+	}
+
+	/* Flush any pending characters in the driver and discipline. */
+	serdev_device_write_flush(hu->serdev);
+
+	if (test_bit(HCI_UART_PROTO_READY, &hu->flags))
+		hu->proto->flush(hu);
+
+	return 0;
+}
+
+/* Initialize device */
+static int hci_uart_open(struct hci_dev *hdev)
+{
+	struct hci_uart *hu = hci_get_drvdata(hdev);
+	int err;
+
+	BT_DBG("%s %p", hdev->name, hdev);
+
+	/* When Quirk HCI_QUIRK_NON_PERSISTENT_SETUP is set by
+	 * driver, BT SoC is completely turned OFF during
+	 * BT OFF. Upon next BT ON UART port should be opened.
+	 */
+	if (!test_bit(HCI_UART_PROTO_READY, &hu->flags)) {
+		err = serdev_device_open(hu->serdev);
+		if (err)
+			return err;
+		set_bit(HCI_UART_PROTO_READY, &hu->flags);
+	}
+
+	/* Undo clearing this from hci_uart_close() */
+	hdev->flush = hci_uart_flush;
+
+	return 0;
+}
+
+/* Close device */
+static int hci_uart_close(struct hci_dev *hdev)
+{
+	struct hci_uart *hu = hci_get_drvdata(hdev);
+
+	BT_DBG("hdev %p", hdev);
+
+	if (!test_bit(HCI_UART_PROTO_READY, &hu->flags))
+		return 0;
+
+	hci_uart_flush(hdev);
+	hdev->flush = NULL;
+
+	/* When QUIRK HCI_QUIRK_NON_PERSISTENT_SETUP is set by driver,
+	 * BT SOC is completely powered OFF during BT OFF, holding port
+	 * open may drain the battery.
+	 */
+	if (hci_test_quirk(hdev, HCI_QUIRK_NON_PERSISTENT_SETUP)) {
+		clear_bit(HCI_UART_PROTO_READY, &hu->flags);
+		serdev_device_close(hu->serdev);
+	}
+
+	return 0;
+}
+
+/* Send frames from HCI layer */
+static int hci_uart_send_frame(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	struct hci_uart *hu = hci_get_drvdata(hdev);
+
+	BT_DBG("%s: type %d len %d", hdev->name, hci_skb_pkt_type(skb),
+	       skb->len);
+
+	hu->proto->enqueue(hu, skb);
+
+	hci_uart_tx_wakeup(hu);
+
+	return 0;
+}
+
+static int hci_uart_setup(struct hci_dev *hdev)
+{
+	struct hci_uart *hu = hci_get_drvdata(hdev);
+	struct hci_rp_read_local_version *ver;
+	struct sk_buff *skb;
+	unsigned int speed;
+	int err;
+
+	/* Init speed if any */
+	if (hu->init_speed)
+		speed = hu->init_speed;
+	else if (hu->proto->init_speed)
+		speed = hu->proto->init_speed;
+	else
+		speed = 0;
+
+	if (speed)
+		serdev_device_set_baudrate(hu->serdev, speed);
+
+	/* Operational speed if any */
+	if (hu->oper_speed)
+		speed = hu->oper_speed;
+	else if (hu->proto->oper_speed)
+		speed = hu->proto->oper_speed;
+	else
+		speed = 0;
+
+	if (hu->proto->set_baudrate && speed) {
+		err = hu->proto->set_baudrate(hu, speed);
+		if (err)
+			bt_dev_err(hdev, "Failed to set baudrate");
+		else
+			serdev_device_set_baudrate(hu->serdev, speed);
+	}
+
+	if (hu->proto->setup)
+		return hu->proto->setup(hu);
+
+	if (!test_bit(HCI_UART_VND_DETECT, &hu->hdev_flags))
+		return 0;
+
+	skb = __hci_cmd_sync(hdev, HCI_OP_READ_LOCAL_VERSION, 0, NULL,
+			     HCI_INIT_TIMEOUT);
+	if (IS_ERR(skb)) {
+		bt_dev_err(hdev, "Reading local version info failed (%ld)",
+			   PTR_ERR(skb));
+		return PTR_ERR(skb);
+	}
+
+	if (skb->len != sizeof(*ver))
+		bt_dev_err(hdev, "Event length mismatch for version info");
+
+	kfree_skb(skb);
+	return 0;
+}
+
+/* Check if the device is wakeable */
+static bool hci_uart_wakeup(struct hci_dev *hdev)
+{
+	/* HCI UART devices are assumed to be wakeable by default.
+	 * Implement wakeup callback to override this behavior.
+	 */
+	return true;
+}
+
+/** hci_uart_write_wakeup - transmit buffer wakeup
+ * @serdev: serial device
+ *
+ * This function is called by the serdev framework when it accepts
+ * more data being sent.
+ */
+static void hci_uart_write_wakeup(struct serdev_device *serdev)
+{
+	struct hci_uart *hu = serdev_device_get_drvdata(serdev);
+
+	BT_DBG("");
+
+	if (!hu || serdev != hu->serdev) {
+		WARN_ON(1);
+		return;
+	}
+
+	if (test_bit(HCI_UART_PROTO_READY, &hu->flags))
+		hci_uart_tx_wakeup(hu);
+}
+
+/** hci_uart_receive_buf - receive buffer wakeup
+ * @serdev: serial device
+ * @data:   pointer to received data
+ * @count:  count of received data in bytes
+ *
+ * This function is called by the serdev framework when it received data
+ * in the RX buffer.
+ *
+ * Return: number of processed bytes
+ */
+static size_t hci_uart_receive_buf(struct serdev_device *serdev,
+				   const u8 *data, size_t count)
+{
+	struct hci_uart *hu = serdev_device_get_drvdata(serdev);
+
+	if (!hu || serdev != hu->serdev) {
+		WARN_ON(1);
+		return 0;
+	}
+
+	if (!test_bit(HCI_UART_PROTO_READY, &hu->flags))
+		return 0;
+
+	/* It does not need a lock here as it is already protected by a mutex in
+	 * tty caller
+	 */
+	hu->proto->recv(hu, data, count);
+
+	if (hu->hdev)
+		hu->hdev->stat.byte_rx += count;
+
+	return count;
+}
+
+static const struct serdev_device_ops hci_serdev_client_ops = {
+	.receive_buf = hci_uart_receive_buf,
+	.write_wakeup = hci_uart_write_wakeup,
+};
+
+int hci_uart_register_device_priv(struct hci_uart *hu,
+			     const struct hci_uart_proto *p,
+			     int sizeof_priv)
+{
+	int err;
+	struct hci_dev *hdev;
+
+	BT_DBG("");
+
+	serdev_device_set_client_ops(hu->serdev, &hci_serdev_client_ops);
+
+	if (percpu_init_rwsem(&hu->proto_lock))
+		return -ENOMEM;
+
+	err = serdev_device_open(hu->serdev);
+	if (err)
+		goto err_rwsem;
+
+	err = p->open(hu);
+	if (err)
+		goto err_open;
+
+	hu->proto = p;
+	set_bit(HCI_UART_PROTO_READY, &hu->flags);
+
+	/* Initialize and register HCI device */
+	hdev = hci_alloc_dev_priv(sizeof_priv);
+	if (!hdev) {
+		BT_ERR("Can't allocate HCI device");
+		err = -ENOMEM;
+		goto err_alloc;
+	}
+
+	hu->hdev = hdev;
+
+	hdev->bus = HCI_UART;
+	hci_set_drvdata(hdev, hu);
+
+	INIT_WORK(&hu->init_ready, hci_uart_init_work);
+	INIT_WORK(&hu->write_work, hci_uart_write_work);
+
+	/* Only when vendor specific setup callback is provided, consider
+	 * the manufacturer information valid. This avoids filling in the
+	 * value for Ericsson when nothing is specified.
+	 */
+	if (hu->proto->setup)
+		hdev->manufacturer = hu->proto->manufacturer;
+
+	hdev->open  = hci_uart_open;
+	hdev->close = hci_uart_close;
+	hdev->flush = hci_uart_flush;
+	hdev->send  = hci_uart_send_frame;
+	hdev->setup = hci_uart_setup;
+	if (!hdev->wakeup)
+		hdev->wakeup = hci_uart_wakeup;
+	SET_HCIDEV_DEV(hdev, &hu->serdev->dev);
+
+	if (test_bit(HCI_UART_NO_SUSPEND_NOTIFIER, &hu->flags))
+		hci_set_quirk(hdev, HCI_QUIRK_NO_SUSPEND_NOTIFIER);
+
+	if (test_bit(HCI_UART_RAW_DEVICE, &hu->hdev_flags))
+		hci_set_quirk(hdev, HCI_QUIRK_RAW_DEVICE);
+
+	if (test_bit(HCI_UART_EXT_CONFIG, &hu->hdev_flags))
+		hci_set_quirk(hdev, HCI_QUIRK_EXTERNAL_CONFIG);
+
+	if (test_bit(HCI_UART_INIT_PENDING, &hu->hdev_flags))
+		return 0;
+
+	if (hci_register_dev(hdev) < 0) {
+		BT_ERR("Can't register HCI device");
+		err = -ENODEV;
+		goto err_register;
+	}
+
+	set_bit(HCI_UART_REGISTERED, &hu->flags);
+
+	return 0;
+
+err_register:
+	hci_free_dev(hdev);
+err_alloc:
+	clear_bit(HCI_UART_PROTO_READY, &hu->flags);
+	p->close(hu);
+err_open:
+	serdev_device_close(hu->serdev);
+err_rwsem:
+	percpu_free_rwsem(&hu->proto_lock);
+	return err;
+}
+EXPORT_SYMBOL_GPL(hci_uart_register_device_priv);
+
+void hci_uart_unregister_device(struct hci_uart *hu)
+{
+	struct hci_dev *hdev = hu->hdev;
+
+	cancel_work_sync(&hu->init_ready);
+	if (test_bit(HCI_UART_REGISTERED, &hu->flags))
+		hci_unregister_dev(hdev);
+	hci_free_dev(hdev);
+
+	cancel_work_sync(&hu->write_work);
+
+	hu->proto->close(hu);
+
+	if (test_bit(HCI_UART_PROTO_READY, &hu->flags)) {
+		clear_bit(HCI_UART_PROTO_READY, &hu->flags);
+		serdev_device_close(hu->serdev);
+	}
+	percpu_free_rwsem(&hu->proto_lock);
+}
+EXPORT_SYMBOL_GPL(hci_uart_unregister_device);