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, 142 insertions, 0 deletions

diff --git a/drivers/phy/broadcom/phy-bcm-ns-usb2.c b/drivers/phy/broadcom/phy-bcm-ns-usb2.c
new file mode 100644
index 000000000..c5d35031b
--- /dev/null
+++ b/drivers/phy/broadcom/phy-bcm-ns-usb2.c
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Broadcom Northstar USB 2.0 PHY Driver
+ *
+ * Copyright (C) 2016 Rafał Miłecki <zajec5@gmail.com>
+ */
+
+#include <linux/bcma/bcma.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/phy/phy.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+struct bcm_ns_usb2 {
+	struct device *dev;
+	struct clk *ref_clk;
+	struct phy *phy;
+	struct regmap *clkset;
+	void __iomem *base;
+};
+
+static int bcm_ns_usb2_phy_init(struct phy *phy)
+{
+	struct bcm_ns_usb2 *usb2 = phy_get_drvdata(phy);
+	struct device *dev = usb2->dev;
+	u32 ref_clk_rate, usb2ctl, usb_pll_ndiv, usb_pll_pdiv;
+	int err = 0;
+
+	err = clk_prepare_enable(usb2->ref_clk);
+	if (err < 0) {
+		dev_err(dev, "Failed to prepare ref clock: %d\n", err);
+		goto err_out;
+	}
+
+	ref_clk_rate = clk_get_rate(usb2->ref_clk);
+	if (!ref_clk_rate) {
+		dev_err(dev, "Failed to get ref clock rate\n");
+		err = -EINVAL;
+		goto err_clk_off;
+	}
+
+	usb2ctl = readl(usb2->base);
+
+	if (usb2ctl & BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_PDIV_MASK) {
+		usb_pll_pdiv = usb2ctl;
+		usb_pll_pdiv &= BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_PDIV_MASK;
+		usb_pll_pdiv >>= BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_PDIV_SHIFT;
+	} else {
+		usb_pll_pdiv = 1 << 3;
+	}
+
+	/* Calculate ndiv based on a solid 1920 MHz that is for USB2 PHY */
+	usb_pll_ndiv = (1920000000 * usb_pll_pdiv) / ref_clk_rate;
+
+	/* Unlock DMU PLL settings with some magic value */
+	regmap_write(usb2->clkset, 0, 0x0000ea68);
+
+	/* Write USB 2.0 PLL control setting */
+	usb2ctl &= ~BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_NDIV_MASK;
+	usb2ctl |= usb_pll_ndiv << BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_NDIV_SHIFT;
+
+	writel(usb2ctl, usb2->base);
+
+	/* Lock DMU PLL settings */
+	regmap_write(usb2->clkset, 0, 0x00000000);
+
+err_clk_off:
+	clk_disable_unprepare(usb2->ref_clk);
+err_out:
+	return err;
+}
+
+static const struct phy_ops ops = {
+	.init		= bcm_ns_usb2_phy_init,
+	.owner		= THIS_MODULE,
+};
+
+static int bcm_ns_usb2_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct bcm_ns_usb2 *usb2;
+	struct phy_provider *phy_provider;
+
+	usb2 = devm_kzalloc(&pdev->dev, sizeof(*usb2), GFP_KERNEL);
+	if (!usb2)
+		return -ENOMEM;
+	usb2->dev = dev;
+
+	usb2->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(usb2->base)) {
+		dev_err(dev, "Failed to map control reg\n");
+		return PTR_ERR(usb2->base);
+	}
+
+	usb2->clkset = syscon_regmap_lookup_by_phandle(dev->of_node,
+						       "brcm,syscon-clkset");
+	if (IS_ERR(usb2->clkset)) {
+		dev_err(dev, "Failed to lookup clkset regmap\n");
+		return PTR_ERR(usb2->clkset);
+	}
+
+	usb2->ref_clk = devm_clk_get(dev, "phy-ref-clk");
+	if (IS_ERR(usb2->ref_clk)) {
+		dev_err_probe(dev, PTR_ERR(usb2->ref_clk), "failed to get ref clk\n");
+		return PTR_ERR(usb2->ref_clk);
+	}
+
+	usb2->phy = devm_phy_create(dev, NULL, &ops);
+	if (IS_ERR(usb2->phy))
+		return PTR_ERR(usb2->phy);
+
+	phy_set_drvdata(usb2->phy, usb2);
+	platform_set_drvdata(pdev, usb2);
+
+	phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
+	return PTR_ERR_OR_ZERO(phy_provider);
+}
+
+static const struct of_device_id bcm_ns_usb2_id_table[] = {
+	{ .compatible = "brcm,ns-usb2-phy", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, bcm_ns_usb2_id_table);
+
+static struct platform_driver bcm_ns_usb2_driver = {
+	.probe		= bcm_ns_usb2_probe,
+	.driver = {
+		.name = "bcm_ns_usb2",
+		.of_match_table = bcm_ns_usb2_id_table,
+	},
+};
+module_platform_driver(bcm_ns_usb2_driver);
+
+MODULE_DESCRIPTION("Broadcom Northstar USB 2.0 PHY Driver");
+MODULE_LICENSE("GPL v2");