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, 215 insertions, 0 deletions

diff --git a/drivers/hid/hid-roccat-lua.c b/drivers/hid/hid-roccat-lua.c
new file mode 100644
index 000000000..8e35e1a06
--- /dev/null
+++ b/drivers/hid/hid-roccat-lua.c
@@ -0,0 +1,215 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Roccat Lua driver for Linux
+ *
+ * Copyright (c) 2012 Stefan Achatz <erazor_de@users.sourceforge.net>
+ */
+
+/*
+ */
+
+/*
+ * Roccat Lua is a gamer mouse which cpi, button and light settings can be
+ * configured.
+ */
+
+#include <linux/device.h>
+#include <linux/input.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/hid-roccat.h>
+#include "hid-ids.h"
+#include "hid-roccat-common.h"
+#include "hid-roccat-lua.h"
+
+static ssize_t lua_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);
+	struct lua_device *lua = 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(&lua->lua_lock);
+	retval = roccat_common2_receive(usb_dev, command, buf, real_size);
+	mutex_unlock(&lua->lua_lock);
+
+	return retval ? retval : real_size;
+}
+
+static ssize_t lua_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);
+	struct lua_device *lua = 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(&lua->lua_lock);
+	retval = roccat_common2_send(usb_dev, command, buf, real_size);
+	mutex_unlock(&lua->lua_lock);
+
+	return retval ? retval : real_size;
+}
+
+#define LUA_SYSFS_W(thingy, THINGY) \
+static ssize_t lua_sysfs_write_ ## thingy(struct file *fp, \
+		struct kobject *kobj, const struct bin_attribute *attr, \
+		char *buf, loff_t off, size_t count) \
+{ \
+	return lua_sysfs_write(fp, kobj, buf, off, count, \
+			LUA_SIZE_ ## THINGY, LUA_COMMAND_ ## THINGY); \
+}
+
+#define LUA_SYSFS_R(thingy, THINGY) \
+static ssize_t lua_sysfs_read_ ## thingy(struct file *fp, \
+		struct kobject *kobj, const struct bin_attribute *attr, \
+		char *buf, loff_t off, size_t count) \
+{ \
+	return lua_sysfs_read(fp, kobj, buf, off, count, \
+			LUA_SIZE_ ## THINGY, LUA_COMMAND_ ## THINGY); \
+}
+
+#define LUA_BIN_ATTRIBUTE_RW(thingy, THINGY) \
+LUA_SYSFS_W(thingy, THINGY) \
+LUA_SYSFS_R(thingy, THINGY) \
+static const struct bin_attribute lua_ ## thingy ## _attr = { \
+	.attr = { .name = #thingy, .mode = 0660 }, \
+	.size = LUA_SIZE_ ## THINGY, \
+	.read = lua_sysfs_read_ ## thingy, \
+	.write = lua_sysfs_write_ ## thingy \
+};
+
+LUA_BIN_ATTRIBUTE_RW(control, CONTROL)
+
+static int lua_create_sysfs_attributes(struct usb_interface *intf)
+{
+	return sysfs_create_bin_file(&intf->dev.kobj, &lua_control_attr);
+}
+
+static void lua_remove_sysfs_attributes(struct usb_interface *intf)
+{
+	sysfs_remove_bin_file(&intf->dev.kobj, &lua_control_attr);
+}
+
+static int lua_init_lua_device_struct(struct usb_device *usb_dev,
+		struct lua_device *lua)
+{
+	mutex_init(&lua->lua_lock);
+
+	return 0;
+}
+
+static int lua_init_specials(struct hid_device *hdev)
+{
+	struct usb_interface *intf = to_usb_interface(hdev->dev.parent);
+	struct usb_device *usb_dev = interface_to_usbdev(intf);
+	struct lua_device *lua;
+	int retval;
+
+	lua = kzalloc_obj(*lua);
+	if (!lua) {
+		hid_err(hdev, "can't alloc device descriptor\n");
+		return -ENOMEM;
+	}
+	hid_set_drvdata(hdev, lua);
+
+	retval = lua_init_lua_device_struct(usb_dev, lua);
+	if (retval) {
+		hid_err(hdev, "couldn't init struct lua_device\n");
+		goto exit;
+	}
+
+	retval = lua_create_sysfs_attributes(intf);
+	if (retval) {
+		hid_err(hdev, "cannot create sysfs files\n");
+		goto exit;
+	}
+
+	return 0;
+exit:
+	kfree(lua);
+	return retval;
+}
+
+static void lua_remove_specials(struct hid_device *hdev)
+{
+	struct usb_interface *intf = to_usb_interface(hdev->dev.parent);
+	struct lua_device *lua;
+
+	lua_remove_sysfs_attributes(intf);
+
+	lua = hid_get_drvdata(hdev);
+	kfree(lua);
+}
+
+static int lua_probe(struct hid_device *hdev,
+		const struct hid_device_id *id)
+{
+	int retval;
+
+	if (!hid_is_usb(hdev))
+		return -EINVAL;
+
+	retval = hid_parse(hdev);
+	if (retval) {
+		hid_err(hdev, "parse failed\n");
+		goto exit;
+	}
+
+	retval = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+	if (retval) {
+		hid_err(hdev, "hw start failed\n");
+		goto exit;
+	}
+
+	retval = lua_init_specials(hdev);
+	if (retval) {
+		hid_err(hdev, "couldn't install mouse\n");
+		goto exit_stop;
+	}
+
+	return 0;
+
+exit_stop:
+	hid_hw_stop(hdev);
+exit:
+	return retval;
+}
+
+static void lua_remove(struct hid_device *hdev)
+{
+	lua_remove_specials(hdev);
+	hid_hw_stop(hdev);
+}
+
+static const struct hid_device_id lua_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ROCCAT, USB_DEVICE_ID_ROCCAT_LUA) },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(hid, lua_devices);
+
+static struct hid_driver lua_driver = {
+		.name = "lua",
+		.id_table = lua_devices,
+		.probe = lua_probe,
+		.remove = lua_remove
+};
+module_hid_driver(lua_driver);
+
+MODULE_AUTHOR("Stefan Achatz");
+MODULE_DESCRIPTION("USB Roccat Lua driver");
+MODULE_LICENSE("GPL v2");