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, 194 insertions, 0 deletions

diff --git a/drivers/input/joystick/maplecontrol.c b/drivers/input/joystick/maplecontrol.c
new file mode 100644
index 000000000..6293b6e81
--- /dev/null
+++ b/drivers/input/joystick/maplecontrol.c
@@ -0,0 +1,194 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *	SEGA Dreamcast controller driver
+ *	Based on drivers/usb/iforce.c
+ *
+ *	Copyright Yaegashi Takeshi, 2001
+ *	Adrian McMenamin, 2008 - 2009
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/input.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/timer.h>
+#include <linux/maple.h>
+
+MODULE_AUTHOR("Adrian McMenamin <adrian@mcmen.demon.co.uk>");
+MODULE_DESCRIPTION("SEGA Dreamcast controller driver");
+MODULE_LICENSE("GPL");
+
+struct dc_pad {
+	struct input_dev *dev;
+	struct maple_device *mdev;
+};
+
+static void dc_pad_callback(struct mapleq *mq)
+{
+	unsigned short buttons;
+	struct maple_device *mapledev = mq->dev;
+	struct dc_pad *pad = maple_get_drvdata(mapledev);
+	struct input_dev *dev = pad->dev;
+	unsigned char *res = mq->recvbuf->buf;
+
+	buttons = ~le16_to_cpup((__le16 *)(res + 8));
+
+	input_report_abs(dev, ABS_HAT0Y,
+		(buttons & 0x0010 ? -1 : 0) + (buttons & 0x0020 ? 1 : 0));
+	input_report_abs(dev, ABS_HAT0X,
+		(buttons & 0x0040 ? -1 : 0) + (buttons & 0x0080 ? 1 : 0));
+	input_report_abs(dev, ABS_HAT1Y,
+		(buttons & 0x1000 ? -1 : 0) + (buttons & 0x2000 ? 1 : 0));
+	input_report_abs(dev, ABS_HAT1X,
+		(buttons & 0x4000 ? -1 : 0) + (buttons & 0x8000 ? 1 : 0));
+
+	input_report_key(dev, BTN_C,      buttons & 0x0001);
+	input_report_key(dev, BTN_B,      buttons & 0x0002);
+	input_report_key(dev, BTN_A,      buttons & 0x0004);
+	input_report_key(dev, BTN_START,  buttons & 0x0008);
+	input_report_key(dev, BTN_Z,      buttons & 0x0100);
+	input_report_key(dev, BTN_Y,      buttons & 0x0200);
+	input_report_key(dev, BTN_X,      buttons & 0x0400);
+	input_report_key(dev, BTN_SELECT, buttons & 0x0800);
+
+	input_report_abs(dev, ABS_GAS,    res[10]);
+	input_report_abs(dev, ABS_BRAKE,  res[11]);
+	input_report_abs(dev, ABS_X,      res[12]);
+	input_report_abs(dev, ABS_Y,      res[13]);
+	input_report_abs(dev, ABS_RX,     res[14]);
+	input_report_abs(dev, ABS_RY,     res[15]);
+}
+
+static int dc_pad_open(struct input_dev *dev)
+{
+	struct dc_pad *pad = dev_get_platdata(&dev->dev);
+
+	maple_getcond_callback(pad->mdev, dc_pad_callback, HZ/20,
+		MAPLE_FUNC_CONTROLLER);
+
+	return 0;
+}
+
+static void dc_pad_close(struct input_dev *dev)
+{
+	struct dc_pad *pad = dev_get_platdata(&dev->dev);
+
+	maple_getcond_callback(pad->mdev, dc_pad_callback, 0,
+		MAPLE_FUNC_CONTROLLER);
+}
+
+/* allow the controller to be used */
+static int probe_maple_controller(struct device *dev)
+{
+	static const short btn_bit[32] = {
+		BTN_C, BTN_B, BTN_A, BTN_START, -1, -1, -1, -1,
+		BTN_Z, BTN_Y, BTN_X, BTN_SELECT, -1, -1, -1, -1,
+		-1, -1, -1, -1, -1, -1, -1, -1,
+		-1, -1, -1, -1, -1, -1, -1, -1,
+	};
+
+	static const short abs_bit[32] = {
+		-1, -1, -1, -1, ABS_HAT0Y, ABS_HAT0Y, ABS_HAT0X, ABS_HAT0X,
+		-1, -1, -1, -1, ABS_HAT1Y, ABS_HAT1Y, ABS_HAT1X, ABS_HAT1X,
+		ABS_GAS, ABS_BRAKE, ABS_X, ABS_Y, ABS_RX, ABS_RY, -1, -1,
+		-1, -1, -1, -1, -1, -1, -1, -1,
+	};
+
+	struct maple_device *mdev = to_maple_dev(dev);
+	struct maple_driver *mdrv = to_maple_driver(dev->driver);
+	int i, error;
+	struct dc_pad *pad;
+	struct input_dev *idev;
+	unsigned long data = be32_to_cpu(mdev->devinfo.function_data[0]);
+
+	pad = kzalloc_obj(*pad);
+	idev = input_allocate_device();
+	if (!pad || !idev) {
+		error = -ENOMEM;
+		goto fail;
+	}
+
+	pad->dev = idev;
+	pad->mdev = mdev;
+
+	maple_set_drvdata(mdev, pad);
+
+	idev->open = dc_pad_open;
+	idev->close = dc_pad_close;
+
+	for (i = 0; i < 32; i++) {
+		if (data & (1 << i)) {
+			if (btn_bit[i] >= 0)
+				__set_bit(btn_bit[i], idev->keybit);
+			else if (abs_bit[i] >= 0)
+				__set_bit(abs_bit[i], idev->absbit);
+		}
+	}
+
+	if (idev->keybit[BIT_WORD(BTN_JOYSTICK)])
+		idev->evbit[0] |= BIT_MASK(EV_KEY);
+
+	if (idev->absbit[0])
+		idev->evbit[0] |= BIT_MASK(EV_ABS);
+
+	for (i = ABS_X; i <= ABS_BRAKE; i++)
+		input_set_abs_params(idev, i, 0, 255, 0, 0);
+
+	for (i = ABS_HAT0X; i <= ABS_HAT3Y; i++)
+		input_set_abs_params(idev, i, 1, -1, 0, 0);
+
+	idev->dev.platform_data = pad;
+	idev->dev.parent = &mdev->dev;
+	idev->name = mdev->product_name;
+	idev->id.bustype = BUS_HOST;
+
+	error = input_register_device(idev);
+	if (error)
+		goto fail;
+
+	mdev->driver = mdrv;
+
+	return 0;
+
+fail:
+	input_free_device(idev);
+	kfree(pad);
+	maple_set_drvdata(mdev, NULL);
+	return error;
+}
+
+static int remove_maple_controller(struct device *dev)
+{
+	struct maple_device *mdev = to_maple_dev(dev);
+	struct dc_pad *pad = maple_get_drvdata(mdev);
+
+	mdev->callback = NULL;
+	input_unregister_device(pad->dev);
+	maple_set_drvdata(mdev, NULL);
+	kfree(pad);
+
+	return 0;
+}
+
+static struct maple_driver dc_pad_driver = {
+	.function =	MAPLE_FUNC_CONTROLLER,
+	.drv = {
+		.name	= "Dreamcast_controller",
+		.probe	= probe_maple_controller,
+		.remove	= remove_maple_controller,
+	},
+};
+
+static int __init dc_pad_init(void)
+{
+	return maple_driver_register(&dc_pad_driver);
+}
+
+static void __exit dc_pad_exit(void)
+{
+	maple_driver_unregister(&dc_pad_driver);
+}
+
+module_init(dc_pad_init);
+module_exit(dc_pad_exit);