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, 185 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/dynapro.c b/drivers/input/touchscreen/dynapro.c
new file mode 100644
index 000000000..943ba8c2f
--- /dev/null
+++ b/drivers/input/touchscreen/dynapro.c
@@ -0,0 +1,185 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Dynapro serial touchscreen driver
+ *
+ * Copyright (c) 2009 Tias Guns
+ * Based on the inexio driver (c) Vojtech Pavlik and Dan Streetman and
+ * Richard Lemon
+ */
+
+
+/*
+ * 2009/09/19 Tias Guns <tias@ulyssis.org>
+ *   Copied inexio.c and edited for Dynapro protocol (from retired Xorg module)
+ */
+
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/input.h>
+#include <linux/serio.h>
+
+#define DRIVER_DESC	"Dynapro serial touchscreen driver"
+
+MODULE_AUTHOR("Tias Guns <tias@ulyssis.org>");
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
+
+/*
+ * Definitions & global arrays.
+ */
+
+#define DYNAPRO_FORMAT_TOUCH_BIT 0x40
+#define DYNAPRO_FORMAT_LENGTH 3
+#define DYNAPRO_RESPONSE_BEGIN_BYTE 0x80
+
+#define DYNAPRO_MIN_XC 0
+#define DYNAPRO_MAX_XC 0x3ff
+#define DYNAPRO_MIN_YC 0
+#define DYNAPRO_MAX_YC 0x3ff
+
+#define DYNAPRO_GET_XC(data) (data[1] | ((data[0] & 0x38) << 4))
+#define DYNAPRO_GET_YC(data) (data[2] | ((data[0] & 0x07) << 7))
+#define DYNAPRO_GET_TOUCHED(data) (DYNAPRO_FORMAT_TOUCH_BIT & data[0])
+
+/*
+ * Per-touchscreen data.
+ */
+
+struct dynapro {
+	struct input_dev *dev;
+	struct serio *serio;
+	int idx;
+	unsigned char data[DYNAPRO_FORMAT_LENGTH];
+	char phys[32];
+};
+
+static void dynapro_process_data(struct dynapro *pdynapro)
+{
+	struct input_dev *dev = pdynapro->dev;
+
+	if (DYNAPRO_FORMAT_LENGTH == ++pdynapro->idx) {
+		input_report_abs(dev, ABS_X, DYNAPRO_GET_XC(pdynapro->data));
+		input_report_abs(dev, ABS_Y, DYNAPRO_GET_YC(pdynapro->data));
+		input_report_key(dev, BTN_TOUCH,
+				 DYNAPRO_GET_TOUCHED(pdynapro->data));
+		input_sync(dev);
+
+		pdynapro->idx = 0;
+	}
+}
+
+static irqreturn_t dynapro_interrupt(struct serio *serio,
+		unsigned char data, unsigned int flags)
+{
+	struct dynapro *pdynapro = serio_get_drvdata(serio);
+
+	pdynapro->data[pdynapro->idx] = data;
+
+	if (DYNAPRO_RESPONSE_BEGIN_BYTE & pdynapro->data[0])
+		dynapro_process_data(pdynapro);
+	else
+		dev_dbg(&serio->dev, "unknown/unsynchronized data: %x\n",
+			pdynapro->data[0]);
+
+	return IRQ_HANDLED;
+}
+
+static void dynapro_disconnect(struct serio *serio)
+{
+	struct dynapro *pdynapro = serio_get_drvdata(serio);
+
+	input_get_device(pdynapro->dev);
+	input_unregister_device(pdynapro->dev);
+	serio_close(serio);
+	serio_set_drvdata(serio, NULL);
+	input_put_device(pdynapro->dev);
+	kfree(pdynapro);
+}
+
+/*
+ * dynapro_connect() is the routine that is called when someone adds a
+ * new serio device that supports dynapro protocol and registers it as
+ * an input device. This is usually accomplished using inputattach.
+ */
+
+static int dynapro_connect(struct serio *serio, struct serio_driver *drv)
+{
+	struct dynapro *pdynapro;
+	struct input_dev *input_dev;
+	int err;
+
+	pdynapro = kzalloc_obj(*pdynapro);
+	input_dev = input_allocate_device();
+	if (!pdynapro || !input_dev) {
+		err = -ENOMEM;
+		goto fail1;
+	}
+
+	pdynapro->serio = serio;
+	pdynapro->dev = input_dev;
+	scnprintf(pdynapro->phys, sizeof(pdynapro->phys),
+		  "%s/input0", serio->phys);
+
+	input_dev->name = "Dynapro Serial TouchScreen";
+	input_dev->phys = pdynapro->phys;
+	input_dev->id.bustype = BUS_RS232;
+	input_dev->id.vendor = SERIO_DYNAPRO;
+	input_dev->id.product = 0;
+	input_dev->id.version = 0x0001;
+	input_dev->dev.parent = &serio->dev;
+	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
+	input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
+	input_set_abs_params(pdynapro->dev, ABS_X,
+			     DYNAPRO_MIN_XC, DYNAPRO_MAX_XC, 0, 0);
+	input_set_abs_params(pdynapro->dev, ABS_Y,
+			     DYNAPRO_MIN_YC, DYNAPRO_MAX_YC, 0, 0);
+
+	serio_set_drvdata(serio, pdynapro);
+
+	err = serio_open(serio, drv);
+	if (err)
+		goto fail2;
+
+	err = input_register_device(pdynapro->dev);
+	if (err)
+		goto fail3;
+
+	return 0;
+
+ fail3:	serio_close(serio);
+ fail2:	serio_set_drvdata(serio, NULL);
+ fail1:	input_free_device(input_dev);
+	kfree(pdynapro);
+	return err;
+}
+
+/*
+ * The serio driver structure.
+ */
+
+static const struct serio_device_id dynapro_serio_ids[] = {
+	{
+		.type	= SERIO_RS232,
+		.proto	= SERIO_DYNAPRO,
+		.id	= SERIO_ANY,
+		.extra	= SERIO_ANY,
+	},
+	{ 0 }
+};
+
+MODULE_DEVICE_TABLE(serio, dynapro_serio_ids);
+
+static struct serio_driver dynapro_drv = {
+	.driver		= {
+		.name	= "dynapro",
+	},
+	.description	= DRIVER_DESC,
+	.id_table	= dynapro_serio_ids,
+	.interrupt	= dynapro_interrupt,
+	.connect	= dynapro_connect,
+	.disconnect	= dynapro_disconnect,
+};
+
+module_serio_driver(dynapro_drv);