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, 296 insertions, 0 deletions

diff --git a/drivers/phy/phy-google-usb.c b/drivers/phy/phy-google-usb.c
new file mode 100644
index 000000000..ab20bc20f
--- /dev/null
+++ b/drivers/phy/phy-google-usb.c
@@ -0,0 +1,296 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * phy-google-usb.c - Google USB PHY driver
+ *
+ * Copyright (C) 2025, Google LLC
+ */
+
+#include <linux/bitfield.h>
+#include <linux/cleanup.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/phy/phy.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/reset.h>
+#include <linux/usb/typec_mux.h>
+
+#define USBCS_USB2PHY_CFG19_OFFSET 0x0
+#define USBCS_USB2PHY_CFG19_PHY_CFG_PLL_FB_DIV GENMASK(19, 8)
+
+#define USBCS_USB2PHY_CFG21_OFFSET 0x8
+#define USBCS_USB2PHY_CFG21_PHY_ENABLE BIT(12)
+#define USBCS_USB2PHY_CFG21_REF_FREQ_SEL GENMASK(15, 13)
+#define USBCS_USB2PHY_CFG21_PHY_TX_DIG_BYPASS_SEL BIT(19)
+
+#define USBCS_PHY_CFG1_OFFSET 0x28
+#define USBCS_PHY_CFG1_SYS_VBUSVALID BIT(17)
+
+enum google_usb_phy_id {
+	GOOGLE_USB2_PHY,
+	GOOGLE_USB_PHY_NUM,
+};
+
+struct google_usb_phy_instance {
+	struct google_usb_phy *parent;
+	unsigned int index;
+	struct phy *phy;
+	unsigned int num_clks;
+	struct clk_bulk_data *clks;
+	unsigned int num_rsts;
+	struct reset_control_bulk_data *rsts;
+};
+
+struct google_usb_phy {
+	struct device *dev;
+	struct regmap *usb_cfg_regmap;
+	unsigned int usb2_cfg_offset;
+	void __iomem *usbdp_top_base;
+	struct google_usb_phy_instance *insts;
+	/*
+	 * Protect phy registers from concurrent access, specifically via
+	 * google_usb_set_orientation callback.
+	 */
+	struct mutex phy_mutex;
+	struct typec_switch_dev *sw;
+	enum typec_orientation orientation;
+};
+
+static void set_vbus_valid(struct google_usb_phy *gphy)
+{
+	u32 reg;
+
+	if (gphy->orientation == TYPEC_ORIENTATION_NONE) {
+		reg = readl(gphy->usbdp_top_base + USBCS_PHY_CFG1_OFFSET);
+		reg &= ~USBCS_PHY_CFG1_SYS_VBUSVALID;
+		writel(reg, gphy->usbdp_top_base + USBCS_PHY_CFG1_OFFSET);
+	} else {
+		reg = readl(gphy->usbdp_top_base + USBCS_PHY_CFG1_OFFSET);
+		reg |= USBCS_PHY_CFG1_SYS_VBUSVALID;
+		writel(reg, gphy->usbdp_top_base + USBCS_PHY_CFG1_OFFSET);
+	}
+}
+
+static int google_usb_set_orientation(struct typec_switch_dev *sw,
+				      enum typec_orientation orientation)
+{
+	struct google_usb_phy *gphy = typec_switch_get_drvdata(sw);
+
+	dev_dbg(gphy->dev, "set orientation %d\n", orientation);
+
+	gphy->orientation = orientation;
+
+	if (pm_runtime_suspended(gphy->dev))
+		return 0;
+
+	guard(mutex)(&gphy->phy_mutex);
+
+	set_vbus_valid(gphy);
+
+	return 0;
+}
+
+static int google_usb2_phy_init(struct phy *_phy)
+{
+	struct google_usb_phy_instance *inst = phy_get_drvdata(_phy);
+	struct google_usb_phy *gphy = inst->parent;
+	u32 reg;
+	int ret;
+
+	dev_dbg(gphy->dev, "initializing usb2 phy\n");
+
+	guard(mutex)(&gphy->phy_mutex);
+
+	regmap_read(gphy->usb_cfg_regmap, gphy->usb2_cfg_offset + USBCS_USB2PHY_CFG21_OFFSET, &reg);
+	reg &= ~USBCS_USB2PHY_CFG21_PHY_TX_DIG_BYPASS_SEL;
+	reg &= ~USBCS_USB2PHY_CFG21_REF_FREQ_SEL;
+	reg |= FIELD_PREP(USBCS_USB2PHY_CFG21_REF_FREQ_SEL, 0);
+	regmap_write(gphy->usb_cfg_regmap, gphy->usb2_cfg_offset + USBCS_USB2PHY_CFG21_OFFSET, reg);
+
+	regmap_read(gphy->usb_cfg_regmap, gphy->usb2_cfg_offset + USBCS_USB2PHY_CFG19_OFFSET, &reg);
+	reg &= ~USBCS_USB2PHY_CFG19_PHY_CFG_PLL_FB_DIV;
+	reg |= FIELD_PREP(USBCS_USB2PHY_CFG19_PHY_CFG_PLL_FB_DIV, 368);
+	regmap_write(gphy->usb_cfg_regmap, gphy->usb2_cfg_offset + USBCS_USB2PHY_CFG19_OFFSET, reg);
+
+	set_vbus_valid(gphy);
+
+	ret = clk_bulk_prepare_enable(inst->num_clks, inst->clks);
+	if (ret)
+		return ret;
+
+	ret = reset_control_bulk_deassert(inst->num_rsts, inst->rsts);
+	if (ret) {
+		clk_bulk_disable_unprepare(inst->num_clks, inst->clks);
+		return ret;
+	}
+
+	regmap_read(gphy->usb_cfg_regmap, gphy->usb2_cfg_offset + USBCS_USB2PHY_CFG21_OFFSET, &reg);
+	reg |= USBCS_USB2PHY_CFG21_PHY_ENABLE;
+	regmap_write(gphy->usb_cfg_regmap, gphy->usb2_cfg_offset + USBCS_USB2PHY_CFG21_OFFSET, reg);
+
+	return 0;
+}
+
+static int google_usb2_phy_exit(struct phy *_phy)
+{
+	struct google_usb_phy_instance *inst = phy_get_drvdata(_phy);
+	struct google_usb_phy *gphy = inst->parent;
+	u32 reg;
+
+	dev_dbg(gphy->dev, "exiting usb2 phy\n");
+
+	guard(mutex)(&gphy->phy_mutex);
+
+	regmap_read(gphy->usb_cfg_regmap, gphy->usb2_cfg_offset + USBCS_USB2PHY_CFG21_OFFSET, &reg);
+	reg &= ~USBCS_USB2PHY_CFG21_PHY_ENABLE;
+	regmap_write(gphy->usb_cfg_regmap, gphy->usb2_cfg_offset + USBCS_USB2PHY_CFG21_OFFSET, reg);
+
+	reset_control_bulk_assert(inst->num_rsts, inst->rsts);
+	clk_bulk_disable_unprepare(inst->num_clks, inst->clks);
+
+	return 0;
+}
+
+static const struct phy_ops google_usb2_phy_ops = {
+	.init		= google_usb2_phy_init,
+	.exit		= google_usb2_phy_exit,
+};
+
+static struct phy *google_usb_phy_xlate(struct device *dev,
+					const struct of_phandle_args *args)
+{
+	struct google_usb_phy *gphy = dev_get_drvdata(dev);
+
+	if (args->args[0] >= GOOGLE_USB_PHY_NUM) {
+		dev_err(dev, "invalid PHY index requested from DT\n");
+		return ERR_PTR(-ENODEV);
+	}
+	return gphy->insts[args->args[0]].phy;
+}
+
+static int google_usb_phy_probe(struct platform_device *pdev)
+{
+	struct typec_switch_desc sw_desc = { };
+	struct google_usb_phy_instance *inst;
+	struct phy_provider *phy_provider;
+	struct device *dev = &pdev->dev;
+	struct google_usb_phy *gphy;
+	struct phy *phy;
+	u32 args[1];
+	int ret;
+
+	gphy = devm_kzalloc(dev, sizeof(*gphy), GFP_KERNEL);
+	if (!gphy)
+		return -ENOMEM;
+
+	dev_set_drvdata(dev, gphy);
+	gphy->dev = dev;
+
+	ret = devm_mutex_init(dev, &gphy->phy_mutex);
+	if (ret)
+		return ret;
+
+	gphy->usb_cfg_regmap =
+		syscon_regmap_lookup_by_phandle_args(dev->of_node,
+						     "google,usb-cfg-csr",
+						     ARRAY_SIZE(args), args);
+	if (IS_ERR(gphy->usb_cfg_regmap)) {
+		return dev_err_probe(dev, PTR_ERR(gphy->usb_cfg_regmap),
+				     "invalid usb cfg csr\n");
+	}
+
+	gphy->usb2_cfg_offset = args[0];
+
+	gphy->usbdp_top_base = devm_platform_ioremap_resource_byname(pdev,
+								     "usbdp_top");
+	if (IS_ERR(gphy->usbdp_top_base))
+		return dev_err_probe(dev, PTR_ERR(gphy->usbdp_top_base),
+				    "invalid usbdp top\n");
+
+	gphy->insts = devm_kcalloc(dev, GOOGLE_USB_PHY_NUM, sizeof(*gphy->insts), GFP_KERNEL);
+	if (!gphy->insts)
+		return -ENOMEM;
+
+	inst = &gphy->insts[GOOGLE_USB2_PHY];
+	inst->parent = gphy;
+	inst->index = GOOGLE_USB2_PHY;
+	phy = devm_phy_create(dev, NULL, &google_usb2_phy_ops);
+	if (IS_ERR(phy))
+		return dev_err_probe(dev, PTR_ERR(phy),
+				     "failed to create usb2 phy instance\n");
+	inst->phy = phy;
+	phy_set_drvdata(phy, inst);
+
+	inst->num_clks = 2;
+	inst->clks = devm_kcalloc(dev, inst->num_clks, sizeof(*inst->clks), GFP_KERNEL);
+	if (!inst->clks)
+		return -ENOMEM;
+	inst->clks[0].id = "usb2";
+	inst->clks[1].id = "usb2_apb";
+	ret = devm_clk_bulk_get(dev, inst->num_clks, inst->clks);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to get u2 phy clks\n");
+
+	inst->num_rsts = 2;
+	inst->rsts = devm_kcalloc(dev, inst->num_rsts, sizeof(*inst->rsts), GFP_KERNEL);
+	if (!inst->rsts)
+		return -ENOMEM;
+	inst->rsts[0].id = "usb2";
+	inst->rsts[1].id = "usb2_apb";
+	ret = devm_reset_control_bulk_get_exclusive(dev, inst->num_rsts, inst->rsts);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to get u2 phy resets\n");
+
+	phy_provider = devm_of_phy_provider_register(dev, google_usb_phy_xlate);
+	if (IS_ERR(phy_provider))
+		return dev_err_probe(dev, PTR_ERR(phy_provider),
+				     "failed to register phy provider\n");
+
+	pm_runtime_enable(dev);
+
+	sw_desc.fwnode = dev_fwnode(dev);
+	sw_desc.drvdata = gphy;
+	sw_desc.name = fwnode_get_name(dev_fwnode(dev));
+	sw_desc.set = google_usb_set_orientation;
+
+	gphy->sw = typec_switch_register(dev, &sw_desc);
+	if (IS_ERR(gphy->sw))
+		return dev_err_probe(dev, PTR_ERR(gphy->sw),
+				     "failed to register typec switch\n");
+
+	return 0;
+}
+
+static void google_usb_phy_remove(struct platform_device *pdev)
+{
+	struct google_usb_phy *gphy = dev_get_drvdata(&pdev->dev);
+
+	typec_switch_unregister(gphy->sw);
+	pm_runtime_disable(&pdev->dev);
+}
+
+static const struct of_device_id google_usb_phy_of_match[] = {
+	{
+		.compatible = "google,lga-usb-phy",
+	},
+	{ }
+};
+MODULE_DEVICE_TABLE(of, google_usb_phy_of_match);
+
+static struct platform_driver google_usb_phy = {
+	.probe	= google_usb_phy_probe,
+	.remove = google_usb_phy_remove,
+	.driver = {
+		.name		= "google-usb-phy",
+		.of_match_table	= google_usb_phy_of_match,
+	}
+};
+
+module_platform_driver(google_usb_phy);
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Google USB phy driver");