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, 302 insertions, 0 deletions

diff --git a/drivers/nvmem/rockchip-efuse.c b/drivers/nvmem/rockchip-efuse.c
new file mode 100644
index 000000000..013e67136
--- /dev/null
+++ b/drivers/nvmem/rockchip-efuse.c
@@ -0,0 +1,302 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Rockchip eFuse Driver
+ *
+ * Copyright (c) 2015 Rockchip Electronics Co. Ltd.
+ * Author: Caesar Wang <wxt@rock-chips.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+
+#define RK3288_A_SHIFT		6
+#define RK3288_A_MASK		0x3ff
+#define RK3288_PGENB		BIT(3)
+#define RK3288_LOAD		BIT(2)
+#define RK3288_STROBE		BIT(1)
+#define RK3288_CSB		BIT(0)
+
+#define RK3328_SECURE_SIZES	96
+#define RK3328_INT_STATUS	0x0018
+#define RK3328_DOUT		0x0020
+#define RK3328_AUTO_CTRL	0x0024
+#define RK3328_INT_FINISH	BIT(0)
+#define RK3328_AUTO_ENB		BIT(0)
+#define RK3328_AUTO_RD		BIT(1)
+
+#define RK3399_A_SHIFT		16
+#define RK3399_A_MASK		0x3ff
+#define RK3399_NBYTES		4
+#define RK3399_STROBSFTSEL	BIT(9)
+#define RK3399_RSB		BIT(7)
+#define RK3399_PD		BIT(5)
+#define RK3399_PGENB		BIT(3)
+#define RK3399_LOAD		BIT(2)
+#define RK3399_STROBE		BIT(1)
+#define RK3399_CSB		BIT(0)
+
+#define REG_EFUSE_CTRL		0x0000
+#define REG_EFUSE_DOUT		0x0004
+
+struct rockchip_efuse_chip {
+	struct device *dev;
+	void __iomem *base;
+	struct clk *clk;
+};
+
+static int rockchip_rk3288_efuse_read(void *context, unsigned int offset,
+				      void *val, size_t bytes)
+{
+	struct rockchip_efuse_chip *efuse = context;
+	u8 *buf = val;
+	int ret;
+
+	ret = clk_prepare_enable(efuse->clk);
+	if (ret < 0) {
+		dev_err(efuse->dev, "failed to prepare/enable efuse clk\n");
+		return ret;
+	}
+
+	writel(RK3288_LOAD | RK3288_PGENB, efuse->base + REG_EFUSE_CTRL);
+	udelay(1);
+	while (bytes--) {
+		writel(readl(efuse->base + REG_EFUSE_CTRL) &
+			     (~(RK3288_A_MASK << RK3288_A_SHIFT)),
+			     efuse->base + REG_EFUSE_CTRL);
+		writel(readl(efuse->base + REG_EFUSE_CTRL) |
+			     ((offset++ & RK3288_A_MASK) << RK3288_A_SHIFT),
+			     efuse->base + REG_EFUSE_CTRL);
+		udelay(1);
+		writel(readl(efuse->base + REG_EFUSE_CTRL) |
+			     RK3288_STROBE, efuse->base + REG_EFUSE_CTRL);
+		udelay(1);
+		*buf++ = readb(efuse->base + REG_EFUSE_DOUT);
+		writel(readl(efuse->base + REG_EFUSE_CTRL) &
+		       (~RK3288_STROBE), efuse->base + REG_EFUSE_CTRL);
+		udelay(1);
+	}
+
+	/* Switch to standby mode */
+	writel(RK3288_PGENB | RK3288_CSB, efuse->base + REG_EFUSE_CTRL);
+
+	clk_disable_unprepare(efuse->clk);
+
+	return 0;
+}
+
+static int rockchip_rk3328_efuse_read(void *context, unsigned int offset,
+				      void *val, size_t bytes)
+{
+	struct rockchip_efuse_chip *efuse = context;
+	unsigned int addr_start, addr_end, addr_offset, addr_len;
+	u32 out_value, status;
+	u8 *buf;
+	int ret, i = 0;
+
+	ret = clk_prepare_enable(efuse->clk);
+	if (ret < 0) {
+		dev_err(efuse->dev, "failed to prepare/enable efuse clk\n");
+		return ret;
+	}
+
+	/* 128 Byte efuse, 96 Byte for secure, 32 Byte for non-secure */
+	offset += RK3328_SECURE_SIZES;
+	addr_start = rounddown(offset, RK3399_NBYTES) / RK3399_NBYTES;
+	addr_end = roundup(offset + bytes, RK3399_NBYTES) / RK3399_NBYTES;
+	addr_offset = offset % RK3399_NBYTES;
+	addr_len = addr_end - addr_start;
+
+	buf = kzalloc(array3_size(addr_len, RK3399_NBYTES, sizeof(*buf)),
+		      GFP_KERNEL);
+	if (!buf) {
+		ret = -ENOMEM;
+		goto nomem;
+	}
+
+	while (addr_len--) {
+		writel(RK3328_AUTO_RD | RK3328_AUTO_ENB |
+		       ((addr_start++ & RK3399_A_MASK) << RK3399_A_SHIFT),
+		       efuse->base + RK3328_AUTO_CTRL);
+		udelay(4);
+		status = readl(efuse->base + RK3328_INT_STATUS);
+		if (!(status & RK3328_INT_FINISH)) {
+			ret = -EIO;
+			goto err;
+		}
+		out_value = readl(efuse->base + RK3328_DOUT);
+		writel(RK3328_INT_FINISH, efuse->base + RK3328_INT_STATUS);
+
+		memcpy(&buf[i], &out_value, RK3399_NBYTES);
+		i += RK3399_NBYTES;
+	}
+
+	memcpy(val, buf + addr_offset, bytes);
+err:
+	kfree(buf);
+nomem:
+	clk_disable_unprepare(efuse->clk);
+
+	return ret;
+}
+
+static int rockchip_rk3399_efuse_read(void *context, unsigned int offset,
+				      void *val, size_t bytes)
+{
+	struct rockchip_efuse_chip *efuse = context;
+	unsigned int addr_start, addr_end, addr_offset, addr_len;
+	u32 out_value;
+	u8 *buf;
+	int ret, i = 0;
+
+	ret = clk_prepare_enable(efuse->clk);
+	if (ret < 0) {
+		dev_err(efuse->dev, "failed to prepare/enable efuse clk\n");
+		return ret;
+	}
+
+	addr_start = rounddown(offset, RK3399_NBYTES) / RK3399_NBYTES;
+	addr_end = roundup(offset + bytes, RK3399_NBYTES) / RK3399_NBYTES;
+	addr_offset = offset % RK3399_NBYTES;
+	addr_len = addr_end - addr_start;
+
+	buf = kzalloc(array3_size(addr_len, RK3399_NBYTES, sizeof(*buf)),
+		      GFP_KERNEL);
+	if (!buf) {
+		clk_disable_unprepare(efuse->clk);
+		return -ENOMEM;
+	}
+
+	writel(RK3399_LOAD | RK3399_PGENB | RK3399_STROBSFTSEL | RK3399_RSB,
+	       efuse->base + REG_EFUSE_CTRL);
+	udelay(1);
+	while (addr_len--) {
+		writel(readl(efuse->base + REG_EFUSE_CTRL) | RK3399_STROBE |
+		       ((addr_start++ & RK3399_A_MASK) << RK3399_A_SHIFT),
+		       efuse->base + REG_EFUSE_CTRL);
+		udelay(1);
+		out_value = readl(efuse->base + REG_EFUSE_DOUT);
+		writel(readl(efuse->base + REG_EFUSE_CTRL) & (~RK3399_STROBE),
+		       efuse->base + REG_EFUSE_CTRL);
+		udelay(1);
+
+		memcpy(&buf[i], &out_value, RK3399_NBYTES);
+		i += RK3399_NBYTES;
+	}
+
+	/* Switch to standby mode */
+	writel(RK3399_PD | RK3399_CSB, efuse->base + REG_EFUSE_CTRL);
+
+	memcpy(val, buf + addr_offset, bytes);
+
+	kfree(buf);
+
+	clk_disable_unprepare(efuse->clk);
+
+	return 0;
+}
+
+static struct nvmem_config econfig = {
+	.name = "rockchip-efuse",
+	.add_legacy_fixed_of_cells = true,
+	.type = NVMEM_TYPE_OTP,
+	.stride = 1,
+	.word_size = 1,
+	.read_only = true,
+};
+
+static const struct of_device_id rockchip_efuse_match[] = {
+	/* deprecated but kept around for dts binding compatibility */
+	{
+		.compatible = "rockchip,rockchip-efuse",
+		.data = (void *)&rockchip_rk3288_efuse_read,
+	},
+	{
+		.compatible = "rockchip,rk3066a-efuse",
+		.data = (void *)&rockchip_rk3288_efuse_read,
+	},
+	{
+		.compatible = "rockchip,rk3188-efuse",
+		.data = (void *)&rockchip_rk3288_efuse_read,
+	},
+	{
+		.compatible = "rockchip,rk3228-efuse",
+		.data = (void *)&rockchip_rk3288_efuse_read,
+	},
+	{
+		.compatible = "rockchip,rk3288-efuse",
+		.data = (void *)&rockchip_rk3288_efuse_read,
+	},
+	{
+		.compatible = "rockchip,rk3368-efuse",
+		.data = (void *)&rockchip_rk3288_efuse_read,
+	},
+	{
+		.compatible = "rockchip,rk3328-efuse",
+		.data = (void *)&rockchip_rk3328_efuse_read,
+	},
+	{
+		.compatible = "rockchip,rk3399-efuse",
+		.data = (void *)&rockchip_rk3399_efuse_read,
+	},
+	{ /* sentinel */},
+};
+MODULE_DEVICE_TABLE(of, rockchip_efuse_match);
+
+static int rockchip_efuse_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	struct nvmem_device *nvmem;
+	struct rockchip_efuse_chip *efuse;
+	const void *data;
+	struct device *dev = &pdev->dev;
+
+	data = of_device_get_match_data(dev);
+	if (!data) {
+		dev_err(dev, "failed to get match data\n");
+		return -EINVAL;
+	}
+
+	efuse = devm_kzalloc(dev, sizeof(struct rockchip_efuse_chip),
+			     GFP_KERNEL);
+	if (!efuse)
+		return -ENOMEM;
+
+	efuse->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+	if (IS_ERR(efuse->base))
+		return PTR_ERR(efuse->base);
+
+	efuse->clk = devm_clk_get(dev, "pclk_efuse");
+	if (IS_ERR(efuse->clk))
+		return PTR_ERR(efuse->clk);
+
+	efuse->dev = dev;
+	if (of_property_read_u32(dev->of_node, "rockchip,efuse-size",
+				 &econfig.size))
+		econfig.size = resource_size(res);
+	econfig.reg_read = data;
+	econfig.priv = efuse;
+	econfig.dev = efuse->dev;
+	nvmem = devm_nvmem_register(dev, &econfig);
+
+	return PTR_ERR_OR_ZERO(nvmem);
+}
+
+static struct platform_driver rockchip_efuse_driver = {
+	.probe = rockchip_efuse_probe,
+	.driver = {
+		.name = "rockchip-efuse",
+		.of_match_table = rockchip_efuse_match,
+	},
+};
+
+module_platform_driver(rockchip_efuse_driver);
+MODULE_DESCRIPTION("rockchip_efuse driver");
+MODULE_LICENSE("GPL v2");