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, 175 insertions, 0 deletions

diff --git a/drivers/hid/hid-roccat-common.c b/drivers/hid/hid-roccat-common.c
new file mode 100644
index 000000000..4465ef95d
--- /dev/null
+++ b/drivers/hid/hid-roccat-common.c
@@ -0,0 +1,175 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Roccat common functions for device specific drivers
+ *
+ * Copyright (c) 2011 Stefan Achatz <erazor_de@users.sourceforge.net>
+ */
+
+/*
+ */
+
+#include <linux/hid.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include "hid-roccat-common.h"
+
+static inline uint16_t roccat_common2_feature_report(uint8_t report_id)
+{
+	return 0x300 | report_id;
+}
+
+int roccat_common2_receive(struct usb_device *usb_dev, uint report_id,
+		void *data, uint size)
+{
+	char *buf;
+	int len;
+
+	buf = kmalloc(size, GFP_KERNEL);
+	if (buf == NULL)
+		return -ENOMEM;
+
+	len = usb_control_msg(usb_dev, usb_rcvctrlpipe(usb_dev, 0),
+			HID_REQ_GET_REPORT,
+			USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_IN,
+			roccat_common2_feature_report(report_id),
+			0, buf, size, USB_CTRL_SET_TIMEOUT);
+
+	memcpy(data, buf, size);
+	kfree(buf);
+	return ((len < 0) ? len : ((len != size) ? -EIO : 0));
+}
+EXPORT_SYMBOL_GPL(roccat_common2_receive);
+
+int roccat_common2_send(struct usb_device *usb_dev, uint report_id,
+		void const *data, uint size)
+{
+	char *buf;
+	int len;
+
+	buf = kmemdup(data, size, GFP_KERNEL);
+	if (buf == NULL)
+		return -ENOMEM;
+
+	len = usb_control_msg(usb_dev, usb_sndctrlpipe(usb_dev, 0),
+			HID_REQ_SET_REPORT,
+			USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_OUT,
+			roccat_common2_feature_report(report_id),
+			0, buf, size, USB_CTRL_SET_TIMEOUT);
+
+	kfree(buf);
+	return ((len < 0) ? len : ((len != size) ? -EIO : 0));
+}
+EXPORT_SYMBOL_GPL(roccat_common2_send);
+
+enum roccat_common2_control_states {
+	ROCCAT_COMMON_CONTROL_STATUS_CRITICAL = 0,
+	ROCCAT_COMMON_CONTROL_STATUS_OK = 1,
+	ROCCAT_COMMON_CONTROL_STATUS_INVALID = 2,
+	ROCCAT_COMMON_CONTROL_STATUS_BUSY = 3,
+	ROCCAT_COMMON_CONTROL_STATUS_CRITICAL_NEW = 4,
+};
+
+static int roccat_common2_receive_control_status(struct usb_device *usb_dev)
+{
+	int retval;
+	struct roccat_common2_control control;
+
+	do {
+		msleep(50);
+		retval = roccat_common2_receive(usb_dev,
+				ROCCAT_COMMON_COMMAND_CONTROL,
+				&control, sizeof(struct roccat_common2_control));
+
+		if (retval)
+			return retval;
+
+		switch (control.value) {
+		case ROCCAT_COMMON_CONTROL_STATUS_OK:
+			return 0;
+		case ROCCAT_COMMON_CONTROL_STATUS_BUSY:
+			msleep(500);
+			continue;
+		case ROCCAT_COMMON_CONTROL_STATUS_INVALID:
+		case ROCCAT_COMMON_CONTROL_STATUS_CRITICAL:
+		case ROCCAT_COMMON_CONTROL_STATUS_CRITICAL_NEW:
+			return -EINVAL;
+		default:
+			dev_err(&usb_dev->dev,
+					"roccat_common2_receive_control_status: "
+					"unknown response value 0x%x\n",
+					control.value);
+			return -EINVAL;
+		}
+
+	} while (1);
+}
+
+int roccat_common2_send_with_status(struct usb_device *usb_dev,
+		uint command, void const *buf, uint size)
+{
+	int retval;
+
+	retval = roccat_common2_send(usb_dev, command, buf, size);
+	if (retval)
+		return retval;
+
+	msleep(100);
+
+	return roccat_common2_receive_control_status(usb_dev);
+}
+EXPORT_SYMBOL_GPL(roccat_common2_send_with_status);
+
+int roccat_common2_device_init_struct(struct usb_device *usb_dev,
+		struct roccat_common2_device *dev)
+{
+	mutex_init(&dev->lock);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(roccat_common2_device_init_struct);
+
+ssize_t roccat_common2_sysfs_read(struct file *fp, struct kobject *kobj,
+		char *buf, loff_t off, size_t count,
+		size_t real_size, uint command)
+{
+	struct device *dev = kobj_to_dev(kobj)->parent->parent;
+	struct roccat_common2_device *roccat_dev = hid_get_drvdata(dev_get_drvdata(dev));
+	struct usb_device *usb_dev = interface_to_usbdev(to_usb_interface(dev));
+	int retval;
+
+	if (off >= real_size)
+		return 0;
+
+	if (off != 0 || count != real_size)
+		return -EINVAL;
+
+	mutex_lock(&roccat_dev->lock);
+	retval = roccat_common2_receive(usb_dev, command, buf, real_size);
+	mutex_unlock(&roccat_dev->lock);
+
+	return retval ? retval : real_size;
+}
+EXPORT_SYMBOL_GPL(roccat_common2_sysfs_read);
+
+ssize_t roccat_common2_sysfs_write(struct file *fp, struct kobject *kobj,
+		void const *buf, loff_t off, size_t count,
+		size_t real_size, uint command)
+{
+	struct device *dev = kobj_to_dev(kobj)->parent->parent;
+	struct roccat_common2_device *roccat_dev = hid_get_drvdata(dev_get_drvdata(dev));
+	struct usb_device *usb_dev = interface_to_usbdev(to_usb_interface(dev));
+	int retval;
+
+	if (off != 0 || count != real_size)
+		return -EINVAL;
+
+	mutex_lock(&roccat_dev->lock);
+	retval = roccat_common2_send_with_status(usb_dev, command, buf, real_size);
+	mutex_unlock(&roccat_dev->lock);
+
+	return retval ? retval : real_size;
+}
+EXPORT_SYMBOL_GPL(roccat_common2_sysfs_write);
+
+MODULE_AUTHOR("Stefan Achatz");
+MODULE_DESCRIPTION("USB Roccat common driver");
+MODULE_LICENSE("GPL v2");