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, 228 insertions, 0 deletions

diff --git a/drivers/nvmem/sunplus-ocotp.c b/drivers/nvmem/sunplus-ocotp.c
new file mode 100644
index 000000000..6884def3b
--- /dev/null
+++ b/drivers/nvmem/sunplus-ocotp.c
@@ -0,0 +1,228 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * The OCOTP driver for Sunplus	SP7021
+ *
+ * Copyright (C) 2019 Sunplus Technology Inc., All rights reserved.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/platform_device.h>
+
+/*
+ * OTP memory
+ * Each bank contains 4 words (32 bits).
+ * Bank 0 starts at offset 0 from the base.
+ */
+
+#define OTP_WORDS_PER_BANK		4
+#define OTP_WORD_SIZE			sizeof(u32)
+#define OTP_BIT_ADDR_OF_BANK		(8 * OTP_WORD_SIZE * OTP_WORDS_PER_BANK)
+#define QAC628_OTP_NUM_BANKS		8
+#define QAC628_OTP_SIZE			(QAC628_OTP_NUM_BANKS * OTP_WORDS_PER_BANK * OTP_WORD_SIZE)
+#define OTP_READ_TIMEOUT_US		200000
+
+/* HB_GPIO */
+#define ADDRESS_8_DATA			0x20
+
+/* OTP_RX */
+#define OTP_CONTROL_2			0x48
+#define OTP_RD_PERIOD			GENMASK(15, 8)
+#define OTP_RD_PERIOD_MASK		~GENMASK(15, 8)
+#define CPU_CLOCK			FIELD_PREP(OTP_RD_PERIOD, 30)
+#define SEL_BAK_KEY2			BIT(5)
+#define SEL_BAK_KEY2_MASK		~BIT(5)
+#define SW_TRIM_EN			BIT(4)
+#define SW_TRIM_EN_MASK			~BIT(4)
+#define SEL_BAK_KEY			BIT(3)
+#define SEL_BAK_KEY_MASK		~BIT(3)
+#define OTP_READ			BIT(2)
+#define OTP_LOAD_SECURE_DATA		BIT(1)
+#define OTP_LOAD_SECURE_DATA_MASK	~BIT(1)
+#define OTP_DO_CRC			BIT(0)
+#define OTP_DO_CRC_MASK			~BIT(0)
+#define OTP_STATUS			0x4c
+#define OTP_READ_DONE			BIT(4)
+#define OTP_READ_DONE_MASK		~BIT(4)
+#define OTP_LOAD_SECURE_DONE_MASK	~BIT(2)
+#define OTP_READ_ADDRESS		0x50
+
+enum base_type {
+	HB_GPIO,
+	OTPRX,
+	BASEMAX,
+};
+
+struct sp_ocotp_priv {
+	struct device *dev;
+	void __iomem *base[BASEMAX];
+	struct clk *clk;
+};
+
+struct sp_ocotp_data {
+	int size;
+};
+
+static const struct sp_ocotp_data sp_otp_v0 = {
+	.size = QAC628_OTP_SIZE,
+};
+
+static int sp_otp_read_real(struct sp_ocotp_priv *otp, int addr, char *value)
+{
+	unsigned int addr_data;
+	unsigned int byte_shift;
+	unsigned int status;
+	int ret;
+
+	addr_data = addr % (OTP_WORD_SIZE * OTP_WORDS_PER_BANK);
+	addr_data = addr_data / OTP_WORD_SIZE;
+
+	byte_shift = addr % (OTP_WORD_SIZE * OTP_WORDS_PER_BANK);
+	byte_shift = byte_shift % OTP_WORD_SIZE;
+
+	addr = addr / (OTP_WORD_SIZE * OTP_WORDS_PER_BANK);
+	addr = addr * OTP_BIT_ADDR_OF_BANK;
+
+	writel(readl(otp->base[OTPRX] + OTP_STATUS) & OTP_READ_DONE_MASK &
+	       OTP_LOAD_SECURE_DONE_MASK, otp->base[OTPRX] + OTP_STATUS);
+	writel(addr, otp->base[OTPRX] + OTP_READ_ADDRESS);
+	writel(readl(otp->base[OTPRX] + OTP_CONTROL_2) | OTP_READ,
+	       otp->base[OTPRX] + OTP_CONTROL_2);
+	writel(readl(otp->base[OTPRX] + OTP_CONTROL_2) & SEL_BAK_KEY2_MASK & SW_TRIM_EN_MASK
+	       & SEL_BAK_KEY_MASK & OTP_LOAD_SECURE_DATA_MASK & OTP_DO_CRC_MASK,
+	       otp->base[OTPRX] + OTP_CONTROL_2);
+	writel((readl(otp->base[OTPRX] + OTP_CONTROL_2) & OTP_RD_PERIOD_MASK) | CPU_CLOCK,
+	       otp->base[OTPRX] + OTP_CONTROL_2);
+
+	ret = readl_poll_timeout(otp->base[OTPRX] + OTP_STATUS, status,
+				 status & OTP_READ_DONE, 10, OTP_READ_TIMEOUT_US);
+
+	if (ret < 0)
+		return ret;
+
+	*value = (readl(otp->base[HB_GPIO] + ADDRESS_8_DATA + addr_data * OTP_WORD_SIZE)
+		  >> (8 * byte_shift)) & 0xff;
+
+	return ret;
+}
+
+static int sp_ocotp_read(void *priv, unsigned int offset, void *value, size_t bytes)
+{
+	struct sp_ocotp_priv *otp = priv;
+	unsigned int addr;
+	char *buf = value;
+	char val[4];
+	int ret;
+
+	ret = clk_enable(otp->clk);
+	if (ret)
+		return ret;
+
+	*buf = 0;
+	for (addr = offset; addr < (offset + bytes); addr++) {
+		ret = sp_otp_read_real(otp, addr, val);
+		if (ret < 0) {
+			dev_err(otp->dev, "OTP read fail:%d at %d", ret, addr);
+			goto disable_clk;
+		}
+
+		*buf++ = *val;
+	}
+
+disable_clk:
+	clk_disable(otp->clk);
+
+	return ret;
+}
+
+static struct nvmem_config sp_ocotp_nvmem_config = {
+	.name = "sp-ocotp",
+	.add_legacy_fixed_of_cells = true,
+	.read_only = true,
+	.word_size = 1,
+	.size = QAC628_OTP_SIZE,
+	.stride = 1,
+	.reg_read = sp_ocotp_read,
+	.owner = THIS_MODULE,
+};
+
+static int sp_ocotp_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct nvmem_device *nvmem;
+	struct sp_ocotp_priv *otp;
+	int ret;
+
+	otp = devm_kzalloc(dev, sizeof(*otp), GFP_KERNEL);
+	if (!otp)
+		return -ENOMEM;
+
+	otp->dev = dev;
+
+	otp->base[HB_GPIO] = devm_platform_ioremap_resource_byname(pdev, "hb_gpio");
+	if (IS_ERR(otp->base[HB_GPIO]))
+		return PTR_ERR(otp->base[HB_GPIO]);
+
+	otp->base[OTPRX] = devm_platform_ioremap_resource_byname(pdev, "otprx");
+	if (IS_ERR(otp->base[OTPRX]))
+		return PTR_ERR(otp->base[OTPRX]);
+
+	otp->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(otp->clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(otp->clk),
+						"devm_clk_get fail\n");
+
+	ret = clk_prepare(otp->clk);
+	if (ret < 0) {
+		dev_err(dev, "failed to prepare clk: %d\n", ret);
+		return ret;
+	}
+
+	sp_ocotp_nvmem_config.priv = otp;
+	sp_ocotp_nvmem_config.dev = dev;
+
+	nvmem = devm_nvmem_register(dev, &sp_ocotp_nvmem_config);
+	if (IS_ERR(nvmem)) {
+		ret = dev_err_probe(&pdev->dev, PTR_ERR(nvmem),
+						"register nvmem device fail\n");
+		goto err;
+	}
+
+	platform_set_drvdata(pdev, nvmem);
+
+	dev_dbg(dev, "banks:%d x wpb:%d x wsize:%d = %d",
+		(int)QAC628_OTP_NUM_BANKS, (int)OTP_WORDS_PER_BANK,
+		(int)OTP_WORD_SIZE, (int)QAC628_OTP_SIZE);
+
+	return 0;
+err:
+	clk_unprepare(otp->clk);
+	return ret;
+}
+
+static const struct of_device_id sp_ocotp_dt_ids[] = {
+	{ .compatible = "sunplus,sp7021-ocotp", .data = &sp_otp_v0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, sp_ocotp_dt_ids);
+
+static struct platform_driver sp_otp_driver = {
+	.probe     = sp_ocotp_probe,
+	.driver    = {
+		.name           = "sunplus,sp7021-ocotp",
+		.of_match_table = sp_ocotp_dt_ids,
+	}
+};
+module_platform_driver(sp_otp_driver);
+
+MODULE_AUTHOR("Vincent Shih <vincent.sunplus@gmail.com>");
+MODULE_DESCRIPTION("Sunplus On-Chip OTP driver");
+MODULE_LICENSE("GPL");
+