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, 226 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/raspberrypi-ts.c b/drivers/input/touchscreen/raspberrypi-ts.c
new file mode 100644
index 000000000..841d39a44
--- /dev/null
+++ b/drivers/input/touchscreen/raspberrypi-ts.c
@@ -0,0 +1,226 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Raspberry Pi firmware based touchscreen driver
+ *
+ * Copyright (C) 2015, 2017 Raspberry Pi
+ * Copyright (C) 2018 Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
+ */
+
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/bitops.h>
+#include <linux/dma-mapping.h>
+#include <linux/platform_device.h>
+#include <linux/input.h>
+#include <linux/input/mt.h>
+#include <linux/input/touchscreen.h>
+#include <soc/bcm2835/raspberrypi-firmware.h>
+
+#define RPI_TS_DEFAULT_WIDTH	800
+#define RPI_TS_DEFAULT_HEIGHT	480
+
+#define RPI_TS_MAX_SUPPORTED_POINTS	10
+
+#define RPI_TS_FTS_TOUCH_DOWN		0
+#define RPI_TS_FTS_TOUCH_CONTACT	2
+
+#define RPI_TS_POLL_INTERVAL		17	/* 60fps */
+
+#define RPI_TS_NPOINTS_REG_INVALIDATE	99
+
+struct rpi_ts {
+	struct platform_device *pdev;
+	struct input_dev *input;
+	struct touchscreen_properties prop;
+
+	void __iomem *fw_regs_va;
+	dma_addr_t fw_regs_phys;
+
+	int known_ids;
+};
+
+struct rpi_ts_regs {
+	u8 device_mode;
+	u8 gesture_id;
+	u8 num_points;
+	struct rpi_ts_touch {
+		u8 xh;
+		u8 xl;
+		u8 yh;
+		u8 yl;
+		u8 pressure; /* Not supported */
+		u8 area;     /* Not supported */
+	} point[RPI_TS_MAX_SUPPORTED_POINTS];
+};
+
+static void rpi_ts_poll(struct input_dev *input)
+{
+	struct rpi_ts *ts = input_get_drvdata(input);
+	struct rpi_ts_regs regs;
+	int modified_ids = 0;
+	long released_ids;
+	int event_type;
+	int touchid;
+	int x, y;
+	int i;
+
+	memcpy_fromio(&regs, ts->fw_regs_va, sizeof(regs));
+	/*
+	 * We poll the memory based register copy of the touchscreen chip using
+	 * the number of points register to know whether the copy has been
+	 * updated (we write 99 to the memory copy, the GPU will write between
+	 * 0 - 10 points)
+	 */
+	iowrite8(RPI_TS_NPOINTS_REG_INVALIDATE,
+		 ts->fw_regs_va + offsetof(struct rpi_ts_regs, num_points));
+
+	if (regs.num_points == RPI_TS_NPOINTS_REG_INVALIDATE ||
+	    (regs.num_points == 0 && ts->known_ids == 0))
+		return;
+
+	for (i = 0; i < regs.num_points; i++) {
+		x = (((int)regs.point[i].xh & 0xf) << 8) + regs.point[i].xl;
+		y = (((int)regs.point[i].yh & 0xf) << 8) + regs.point[i].yl;
+		touchid = (regs.point[i].yh >> 4) & 0xf;
+		event_type = (regs.point[i].xh >> 6) & 0x03;
+
+		modified_ids |= BIT(touchid);
+
+		if (event_type == RPI_TS_FTS_TOUCH_DOWN ||
+		    event_type == RPI_TS_FTS_TOUCH_CONTACT) {
+			input_mt_slot(input, touchid);
+			input_mt_report_slot_state(input, MT_TOOL_FINGER, 1);
+			touchscreen_report_pos(input, &ts->prop, x, y, true);
+		}
+	}
+
+	released_ids = ts->known_ids & ~modified_ids;
+	for_each_set_bit(i, &released_ids, RPI_TS_MAX_SUPPORTED_POINTS) {
+		input_mt_slot(input, i);
+		input_mt_report_slot_inactive(input);
+		modified_ids &= ~(BIT(i));
+	}
+	ts->known_ids = modified_ids;
+
+	input_mt_sync_frame(input);
+	input_sync(input);
+}
+
+static void rpi_ts_dma_cleanup(void *data)
+{
+	struct rpi_ts *ts = data;
+	struct device *dev = &ts->pdev->dev;
+
+	dma_free_coherent(dev, PAGE_SIZE, ts->fw_regs_va, ts->fw_regs_phys);
+}
+
+static int rpi_ts_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	struct input_dev *input;
+	struct rpi_firmware *fw;
+	struct rpi_ts *ts;
+	u32 touchbuf;
+	int error;
+
+	struct device_node *fw_node __free(device_node) = of_get_parent(np);
+	if (!fw_node) {
+		dev_err(dev, "Missing firmware node\n");
+		return -ENOENT;
+	}
+
+	fw = devm_rpi_firmware_get(&pdev->dev, fw_node);
+	if (!fw)
+		return -EPROBE_DEFER;
+
+	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
+	if (!ts)
+		return -ENOMEM;
+	ts->pdev = pdev;
+
+	ts->fw_regs_va = dma_alloc_coherent(dev, PAGE_SIZE, &ts->fw_regs_phys,
+					    GFP_KERNEL);
+	if (!ts->fw_regs_va) {
+		dev_err(dev, "failed to dma_alloc_coherent\n");
+		return -ENOMEM;
+	}
+
+	error = devm_add_action_or_reset(dev, rpi_ts_dma_cleanup, ts);
+	if (error) {
+		dev_err(dev, "failed to devm_add_action_or_reset, %d\n", error);
+		return error;
+	}
+
+	touchbuf = (u32)ts->fw_regs_phys;
+	error = rpi_firmware_property(fw, RPI_FIRMWARE_FRAMEBUFFER_SET_TOUCHBUF,
+				      &touchbuf, sizeof(touchbuf));
+	if (error || touchbuf != 0) {
+		dev_warn(dev, "Failed to set touchbuf, %d\n", error);
+		return error;
+	}
+
+	input = devm_input_allocate_device(dev);
+	if (!input) {
+		dev_err(dev, "Failed to allocate input device\n");
+		return -ENOMEM;
+	}
+
+	ts->input = input;
+	input_set_drvdata(input, ts);
+
+	input->name = "raspberrypi-ts";
+	input->id.bustype = BUS_HOST;
+
+	input_set_abs_params(input, ABS_MT_POSITION_X, 0,
+			     RPI_TS_DEFAULT_WIDTH, 0, 0);
+	input_set_abs_params(input, ABS_MT_POSITION_Y, 0,
+			     RPI_TS_DEFAULT_HEIGHT, 0, 0);
+	touchscreen_parse_properties(input, true, &ts->prop);
+
+	error = input_mt_init_slots(input, RPI_TS_MAX_SUPPORTED_POINTS,
+				    INPUT_MT_DIRECT);
+	if (error) {
+		dev_err(dev, "could not init mt slots, %d\n", error);
+		return error;
+	}
+
+	error = input_setup_polling(input, rpi_ts_poll);
+	if (error) {
+		dev_err(dev, "could not set up polling mode, %d\n", error);
+		return error;
+	}
+
+	input_set_poll_interval(input, RPI_TS_POLL_INTERVAL);
+
+	error = input_register_device(input);
+	if (error) {
+		dev_err(dev, "could not register input device, %d\n", error);
+		return error;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id rpi_ts_match[] = {
+	{ .compatible = "raspberrypi,firmware-ts", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, rpi_ts_match);
+
+static struct platform_driver rpi_ts_driver = {
+	.driver = {
+		.name = "raspberrypi-ts",
+		.of_match_table = rpi_ts_match,
+	},
+	.probe = rpi_ts_probe,
+};
+module_platform_driver(rpi_ts_driver);
+
+MODULE_AUTHOR("Gordon Hollingworth");
+MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>");
+MODULE_DESCRIPTION("Raspberry Pi firmware based touchscreen driver");
+MODULE_LICENSE("GPL v2");