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, 371 insertions, 0 deletions

diff --git a/drivers/reset/reset-k230.c b/drivers/reset/reset-k230.c
new file mode 100644
index 000000000..c81045bb4
--- /dev/null
+++ b/drivers/reset/reset-k230.c
@@ -0,0 +1,371 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2022-2024 Canaan Bright Sight Co., Ltd
+ * Copyright (C) 2024-2025 Junhui Liu <junhui.liu@pigmoral.tech>
+ *
+ * The reset management module in the K230 SoC provides reset time control
+ * registers. For RST_TYPE_CPU0, RST_TYPE_CPU1 and RST_TYPE_SW_DONE, the period
+ * during which reset is applied or removed while the clock is stopped can be
+ * set up to 15 * 0.25 = 3.75 µs. For RST_TYPE_HW_DONE, that period can be set
+ * up to 255 * 0.25 = 63.75 µs. For RST_TYPE_FLUSH, the reset bit is
+ * automatically cleared by hardware when flush completes.
+ *
+ * Although this driver does not configure the reset time registers, delays have
+ * been added to the assert, deassert, and reset operations to cover the maximum
+ * reset time. Some reset types include done bits whose toggle does not
+ * unambiguously signal whether hardware reset removal or clock-stop period
+ * expiration occurred first. Delays are therefore retained for types with done
+ * bits to ensure safe timing.
+ *
+ * Reference: K230 Technical Reference Manual V0.3.1
+ * https://kendryte-download.canaan-creative.com/developer/k230/HDK/K230%E7%A1%AC%E4%BB%B6%E6%96%87%E6%A1%A3/K230_Technical_Reference_Manual_V0.3.1_20241118.pdf
+ */
+
+#include <linux/cleanup.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+#include <linux/spinlock.h>
+
+#include <dt-bindings/reset/canaan,k230-rst.h>
+
+/**
+ * enum k230_rst_type - K230 reset types
+ * @RST_TYPE_CPU0: Reset type for CPU0
+ *	Automatically clears, has write enable and done bit, active high
+ * @RST_TYPE_CPU1: Reset type for CPU1
+ *	Manually clears, has write enable and done bit, active high
+ * @RST_TYPE_FLUSH: Reset type for CPU L2 cache flush
+ *	Automatically clears, has write enable, no done bit, active high
+ * @RST_TYPE_HW_DONE: Reset type for hardware auto clear
+ *	Automatically clears, no write enable, has done bit, active high
+ * @RST_TYPE_SW_DONE: Reset type for software manual clear
+ *	Manually clears, no write enable and done bit,
+ *	active high if ID is RST_SPI2AXI, otherwise active low
+ */
+enum k230_rst_type {
+	RST_TYPE_CPU0,
+	RST_TYPE_CPU1,
+	RST_TYPE_FLUSH,
+	RST_TYPE_HW_DONE,
+	RST_TYPE_SW_DONE,
+};
+
+struct k230_rst_map {
+	u32			offset;
+	enum k230_rst_type	type;
+	u32			done;
+	u32			reset;
+};
+
+struct k230_rst {
+	struct reset_controller_dev	rcdev;
+	void __iomem			*base;
+	/* protect register read-modify-write */
+	spinlock_t			lock;
+};
+
+static const struct k230_rst_map k230_resets[] = {
+	[RST_CPU0]		= { 0x4,  RST_TYPE_CPU0,    BIT(12), BIT(0) },
+	[RST_CPU1]		= { 0xc,  RST_TYPE_CPU1,    BIT(12), BIT(0) },
+	[RST_CPU0_FLUSH]	= { 0x4,  RST_TYPE_FLUSH,   0,       BIT(4) },
+	[RST_CPU1_FLUSH]	= { 0xc,  RST_TYPE_FLUSH,   0,       BIT(4) },
+	[RST_AI]		= { 0x14, RST_TYPE_HW_DONE, BIT(31), BIT(0) },
+	[RST_VPU]		= { 0x1c, RST_TYPE_HW_DONE, BIT(31), BIT(0) },
+	[RST_HISYS]		= { 0x2c, RST_TYPE_HW_DONE, BIT(4),  BIT(0) },
+	[RST_HISYS_AHB]		= { 0x2c, RST_TYPE_HW_DONE, BIT(5),  BIT(1) },
+	[RST_SDIO0]		= { 0x34, RST_TYPE_HW_DONE, BIT(28), BIT(0) },
+	[RST_SDIO1]		= { 0x34, RST_TYPE_HW_DONE, BIT(29), BIT(1) },
+	[RST_SDIO_AXI]		= { 0x34, RST_TYPE_HW_DONE, BIT(30), BIT(2) },
+	[RST_USB0]		= { 0x3c, RST_TYPE_HW_DONE, BIT(28), BIT(0) },
+	[RST_USB1]		= { 0x3c, RST_TYPE_HW_DONE, BIT(29), BIT(1) },
+	[RST_USB0_AHB]		= { 0x3c, RST_TYPE_HW_DONE, BIT(30), BIT(0) },
+	[RST_USB1_AHB]		= { 0x3c, RST_TYPE_HW_DONE, BIT(31), BIT(1) },
+	[RST_SPI0]		= { 0x44, RST_TYPE_HW_DONE, BIT(28), BIT(0) },
+	[RST_SPI1]		= { 0x44, RST_TYPE_HW_DONE, BIT(29), BIT(1) },
+	[RST_SPI2]		= { 0x44, RST_TYPE_HW_DONE, BIT(30), BIT(2) },
+	[RST_SEC]		= { 0x4c, RST_TYPE_HW_DONE, BIT(31), BIT(0) },
+	[RST_PDMA]		= { 0x54, RST_TYPE_HW_DONE, BIT(28), BIT(0) },
+	[RST_SDMA]		= { 0x54, RST_TYPE_HW_DONE, BIT(29), BIT(1) },
+	[RST_DECOMPRESS]	= { 0x5c, RST_TYPE_HW_DONE, BIT(31), BIT(0) },
+	[RST_SRAM]		= { 0x64, RST_TYPE_HW_DONE, BIT(28), BIT(0) },
+	[RST_SHRM_AXIM]		= { 0x64, RST_TYPE_HW_DONE, BIT(30), BIT(2) },
+	[RST_SHRM_AXIS]		= { 0x64, RST_TYPE_HW_DONE, BIT(31), BIT(3) },
+	[RST_NONAI2D]		= { 0x6c, RST_TYPE_HW_DONE, BIT(31), BIT(0) },
+	[RST_MCTL]		= { 0x74, RST_TYPE_HW_DONE, BIT(31), BIT(0) },
+	[RST_ISP]		= { 0x80, RST_TYPE_HW_DONE, BIT(29), BIT(6) },
+	[RST_ISP_DW]		= { 0x80, RST_TYPE_HW_DONE, BIT(28), BIT(5) },
+	[RST_DPU]		= { 0x88, RST_TYPE_HW_DONE, BIT(31), BIT(0) },
+	[RST_DISP]		= { 0x90, RST_TYPE_HW_DONE, BIT(31), BIT(0) },
+	[RST_GPU]		= { 0x98, RST_TYPE_HW_DONE, BIT(31), BIT(0) },
+	[RST_AUDIO]		= { 0xa4, RST_TYPE_HW_DONE, BIT(31), BIT(0) },
+	[RST_TIMER0]		= { 0x20, RST_TYPE_SW_DONE, 0,       BIT(0) },
+	[RST_TIMER1]		= { 0x20, RST_TYPE_SW_DONE, 0,       BIT(1) },
+	[RST_TIMER2]		= { 0x20, RST_TYPE_SW_DONE, 0,       BIT(2) },
+	[RST_TIMER3]		= { 0x20, RST_TYPE_SW_DONE, 0,       BIT(3) },
+	[RST_TIMER4]		= { 0x20, RST_TYPE_SW_DONE, 0,       BIT(4) },
+	[RST_TIMER5]		= { 0x20, RST_TYPE_SW_DONE, 0,       BIT(5) },
+	[RST_TIMER_APB]		= { 0x20, RST_TYPE_SW_DONE, 0,       BIT(6) },
+	[RST_HDI]		= { 0x20, RST_TYPE_SW_DONE, 0,       BIT(7) },
+	[RST_WDT0]		= { 0x20, RST_TYPE_SW_DONE, 0,       BIT(12) },
+	[RST_WDT1]		= { 0x20, RST_TYPE_SW_DONE, 0,       BIT(13) },
+	[RST_WDT0_APB]		= { 0x20, RST_TYPE_SW_DONE, 0,       BIT(14) },
+	[RST_WDT1_APB]		= { 0x20, RST_TYPE_SW_DONE, 0,       BIT(15) },
+	[RST_TS_APB]		= { 0x20, RST_TYPE_SW_DONE, 0,       BIT(16) },
+	[RST_MAILBOX]		= { 0x20, RST_TYPE_SW_DONE, 0,       BIT(17) },
+	[RST_STC]		= { 0x20, RST_TYPE_SW_DONE, 0,       BIT(18) },
+	[RST_PMU]		= { 0x20, RST_TYPE_SW_DONE, 0,       BIT(19) },
+	[RST_LOSYS_APB]		= { 0x24, RST_TYPE_SW_DONE, 0,       BIT(0) },
+	[RST_UART0]		= { 0x24, RST_TYPE_SW_DONE, 0,       BIT(1) },
+	[RST_UART1]		= { 0x24, RST_TYPE_SW_DONE, 0,       BIT(2) },
+	[RST_UART2]		= { 0x24, RST_TYPE_SW_DONE, 0,       BIT(3) },
+	[RST_UART3]		= { 0x24, RST_TYPE_SW_DONE, 0,       BIT(4) },
+	[RST_UART4]		= { 0x24, RST_TYPE_SW_DONE, 0,       BIT(5) },
+	[RST_I2C0]		= { 0x24, RST_TYPE_SW_DONE, 0,       BIT(6) },
+	[RST_I2C1]		= { 0x24, RST_TYPE_SW_DONE, 0,       BIT(7) },
+	[RST_I2C2]		= { 0x24, RST_TYPE_SW_DONE, 0,       BIT(8) },
+	[RST_I2C3]		= { 0x24, RST_TYPE_SW_DONE, 0,       BIT(9) },
+	[RST_I2C4]		= { 0x24, RST_TYPE_SW_DONE, 0,       BIT(10) },
+	[RST_JAMLINK0_APB]	= { 0x24, RST_TYPE_SW_DONE, 0,       BIT(11) },
+	[RST_JAMLINK1_APB]	= { 0x24, RST_TYPE_SW_DONE, 0,       BIT(12) },
+	[RST_JAMLINK2_APB]	= { 0x24, RST_TYPE_SW_DONE, 0,       BIT(13) },
+	[RST_JAMLINK3_APB]	= { 0x24, RST_TYPE_SW_DONE, 0,       BIT(14) },
+	[RST_CODEC_APB]		= { 0x24, RST_TYPE_SW_DONE, 0,       BIT(17) },
+	[RST_GPIO_DB]		= { 0x24, RST_TYPE_SW_DONE, 0,       BIT(18) },
+	[RST_GPIO_APB]		= { 0x24, RST_TYPE_SW_DONE, 0,       BIT(19) },
+	[RST_ADC]		= { 0x24, RST_TYPE_SW_DONE, 0,       BIT(20) },
+	[RST_ADC_APB]		= { 0x24, RST_TYPE_SW_DONE, 0,       BIT(21) },
+	[RST_PWM_APB]		= { 0x24, RST_TYPE_SW_DONE, 0,       BIT(22) },
+	[RST_SHRM_APB]		= { 0x64, RST_TYPE_SW_DONE, 0,       BIT(1) },
+	[RST_CSI0]		= { 0x80, RST_TYPE_SW_DONE, 0,       BIT(0) },
+	[RST_CSI1]		= { 0x80, RST_TYPE_SW_DONE, 0,       BIT(1) },
+	[RST_CSI2]		= { 0x80, RST_TYPE_SW_DONE, 0,       BIT(2) },
+	[RST_CSI_DPHY]		= { 0x80, RST_TYPE_SW_DONE, 0,       BIT(3) },
+	[RST_ISP_AHB]		= { 0x80, RST_TYPE_SW_DONE, 0,       BIT(4) },
+	[RST_M0]		= { 0x80, RST_TYPE_SW_DONE, 0,       BIT(7) },
+	[RST_M1]		= { 0x80, RST_TYPE_SW_DONE, 0,       BIT(8) },
+	[RST_M2]		= { 0x80, RST_TYPE_SW_DONE, 0,       BIT(9) },
+	[RST_SPI2AXI]		= { 0xa8, RST_TYPE_SW_DONE, 0,       BIT(0) }
+};
+
+static inline struct k230_rst *to_k230_rst(struct reset_controller_dev *rcdev)
+{
+	return container_of(rcdev, struct k230_rst, rcdev);
+}
+
+static void k230_rst_clear_done(struct k230_rst *rstc, unsigned long id,
+				bool write_en)
+{
+	const struct k230_rst_map *rmap = &k230_resets[id];
+	u32 reg;
+
+	guard(spinlock_irqsave)(&rstc->lock);
+
+	reg = readl(rstc->base + rmap->offset);
+	reg |= rmap->done; /* write 1 to clear */
+	if (write_en)
+		reg |= rmap->done << 16;
+	writel(reg, rstc->base + rmap->offset);
+}
+
+static int k230_rst_wait_and_clear_done(struct k230_rst *rstc, unsigned long id,
+					bool write_en)
+{
+	const struct k230_rst_map *rmap = &k230_resets[id];
+	u32 reg;
+	int ret;
+
+	ret = readl_poll_timeout(rstc->base + rmap->offset, reg,
+				 reg & rmap->done, 10, 1000);
+	if (ret) {
+		dev_err(rstc->rcdev.dev, "Wait for reset done timeout\n");
+		return ret;
+	}
+
+	k230_rst_clear_done(rstc, id, write_en);
+
+	return 0;
+}
+
+static void k230_rst_update(struct k230_rst *rstc, unsigned long id,
+			    bool assert, bool write_en, bool active_low)
+{
+	const struct k230_rst_map *rmap = &k230_resets[id];
+	u32 reg;
+
+	guard(spinlock_irqsave)(&rstc->lock);
+
+	reg = readl(rstc->base + rmap->offset);
+	if (assert ^ active_low)
+		reg |= rmap->reset;
+	else
+		reg &= ~rmap->reset;
+	if (write_en)
+		reg |= rmap->reset << 16;
+	writel(reg, rstc->base + rmap->offset);
+}
+
+static int k230_rst_assert(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	struct k230_rst *rstc = to_k230_rst(rcdev);
+
+	switch (k230_resets[id].type) {
+	case RST_TYPE_CPU1:
+		k230_rst_update(rstc, id, true, true, false);
+		break;
+	case RST_TYPE_SW_DONE:
+		k230_rst_update(rstc, id, true, false,
+				id == RST_SPI2AXI ? false : true);
+		break;
+	case RST_TYPE_CPU0:
+	case RST_TYPE_FLUSH:
+	case RST_TYPE_HW_DONE:
+		return -EOPNOTSUPP;
+	}
+
+	/*
+	 * The time period when reset is applied but the clock is stopped for
+	 * RST_TYPE_CPU1 and RST_TYPE_SW_DONE can be set up to 3.75us. Delay
+	 * 10us to ensure proper reset timing.
+	 */
+	udelay(10);
+
+	return 0;
+}
+
+static int k230_rst_deassert(struct reset_controller_dev *rcdev,
+			     unsigned long id)
+{
+	struct k230_rst *rstc = to_k230_rst(rcdev);
+	int ret = 0;
+
+	switch (k230_resets[id].type) {
+	case RST_TYPE_CPU1:
+		k230_rst_update(rstc, id, false, true, false);
+		ret = k230_rst_wait_and_clear_done(rstc, id, true);
+		break;
+	case RST_TYPE_SW_DONE:
+		k230_rst_update(rstc, id, false, false,
+				id == RST_SPI2AXI ? false : true);
+		break;
+	case RST_TYPE_CPU0:
+	case RST_TYPE_FLUSH:
+	case RST_TYPE_HW_DONE:
+		return -EOPNOTSUPP;
+	}
+
+	/*
+	 * The time period when reset is removed but the clock is stopped for
+	 * RST_TYPE_CPU1 and RST_TYPE_SW_DONE can be set up to 3.75us. Delay
+	 * 10us to ensure proper reset timing.
+	 */
+	udelay(10);
+
+	return ret;
+}
+
+static int k230_rst_reset(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	struct k230_rst *rstc = to_k230_rst(rcdev);
+	const struct k230_rst_map *rmap = &k230_resets[id];
+	u32 reg;
+	int ret = 0;
+
+	switch (rmap->type) {
+	case RST_TYPE_CPU0:
+		k230_rst_clear_done(rstc, id, true);
+		k230_rst_update(rstc, id, true, true, false);
+		ret = k230_rst_wait_and_clear_done(rstc, id, true);
+
+		/*
+		 * The time period when reset is applied and removed but the
+		 * clock is stopped for RST_TYPE_CPU0 can be set up to 7.5us.
+		 * Delay 10us to ensure proper reset timing.
+		 */
+		udelay(10);
+
+		break;
+	case RST_TYPE_FLUSH:
+		k230_rst_update(rstc, id, true, true, false);
+
+		/* Wait flush request bit auto cleared by hardware */
+		ret = readl_poll_timeout(rstc->base + rmap->offset, reg,
+					!(reg & rmap->reset), 10, 1000);
+		if (ret)
+			dev_err(rcdev->dev, "Wait for flush done timeout\n");
+
+		break;
+	case RST_TYPE_HW_DONE:
+		k230_rst_clear_done(rstc, id, false);
+		k230_rst_update(rstc, id, true, false, false);
+		ret = k230_rst_wait_and_clear_done(rstc, id, false);
+
+		/*
+		 * The time period when reset is applied and removed but the
+		 * clock is stopped for RST_TYPE_HW_DONE can be set up to
+		 * 127.5us. Delay 200us to ensure proper reset timing.
+		 */
+		fsleep(200);
+
+		break;
+	case RST_TYPE_CPU1:
+	case RST_TYPE_SW_DONE:
+		k230_rst_assert(rcdev, id);
+		ret = k230_rst_deassert(rcdev, id);
+		break;
+	}
+
+	return ret;
+}
+
+static const struct reset_control_ops k230_rst_ops = {
+	.reset		= k230_rst_reset,
+	.assert		= k230_rst_assert,
+	.deassert	= k230_rst_deassert,
+};
+
+static int k230_rst_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct k230_rst *rstc;
+
+	rstc = devm_kzalloc(dev, sizeof(*rstc), GFP_KERNEL);
+	if (!rstc)
+		return -ENOMEM;
+
+	rstc->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(rstc->base))
+		return PTR_ERR(rstc->base);
+
+	spin_lock_init(&rstc->lock);
+
+	rstc->rcdev.dev		= dev;
+	rstc->rcdev.owner	= THIS_MODULE;
+	rstc->rcdev.ops		= &k230_rst_ops;
+	rstc->rcdev.nr_resets	= ARRAY_SIZE(k230_resets);
+	rstc->rcdev.of_node	= dev->of_node;
+
+	return devm_reset_controller_register(dev, &rstc->rcdev);
+}
+
+static const struct of_device_id k230_rst_match[] = {
+	{ .compatible = "canaan,k230-rst", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, k230_rst_match);
+
+static struct platform_driver k230_rst_driver = {
+	.probe = k230_rst_probe,
+	.driver = {
+		.name = "k230-rst",
+		.of_match_table = k230_rst_match,
+	}
+};
+module_platform_driver(k230_rst_driver);
+
+MODULE_AUTHOR("Junhui Liu <junhui.liu@pigmoral.tech>");
+MODULE_DESCRIPTION("Canaan K230 reset driver");
+MODULE_LICENSE("GPL");