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, 167 insertions, 0 deletions

diff --git a/drivers/clk/qcom/hfpll.c b/drivers/clk/qcom/hfpll.c
new file mode 100644
index 000000000..385964196
--- /dev/null
+++ b/drivers/clk/qcom/hfpll.c
@@ -0,0 +1,167 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018, The Linux Foundation. All rights reserved.
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/regmap.h>
+
+#include "clk-regmap.h"
+#include "clk-hfpll.h"
+
+static const struct hfpll_data qcs404 = {
+	.mode_reg = 0x00,
+	.l_reg = 0x04,
+	.m_reg = 0x08,
+	.n_reg = 0x0c,
+	.user_reg = 0x10,
+	.config_reg = 0x14,
+	.config_val = 0x430405d,
+	.status_reg = 0x1c,
+	.lock_bit = 16,
+
+	.user_val = 0x8,
+	.user_vco_mask = 0x100000,
+	.low_vco_max_rate = 1248000000,
+	.min_rate = 537600000UL,
+	.max_rate = 2900000000UL,
+};
+
+static const struct hfpll_data msm8976_a53 = {
+	.mode_reg = 0x00,
+	.l_reg = 0x04,
+	.m_reg = 0x08,
+	.n_reg = 0x0c,
+	.user_reg = 0x10,
+	.config_reg = 0x14,
+	.config_val = 0x341600,
+	.status_reg = 0x1c,
+	.lock_bit = 16,
+
+	.l_val = 0x35,
+	.user_val = 0x109,
+	.min_rate = 902400000UL,
+	.max_rate = 1478400000UL,
+};
+
+static const struct hfpll_data msm8976_a72 = {
+	.mode_reg = 0x00,
+	.l_reg = 0x04,
+	.m_reg = 0x08,
+	.n_reg = 0x0c,
+	.user_reg = 0x10,
+	.config_reg = 0x14,
+	.config_val = 0x4e0405d,
+	.status_reg = 0x1c,
+	.lock_bit = 16,
+
+	.l_val = 0x3e,
+	.user_val = 0x100109,
+	.min_rate = 940800000UL,
+	.max_rate = 2016000000UL,
+};
+
+static const struct hfpll_data msm8976_cci = {
+	.mode_reg = 0x00,
+	.l_reg = 0x04,
+	.m_reg = 0x08,
+	.n_reg = 0x0c,
+	.user_reg = 0x10,
+	.config_reg = 0x14,
+	.config_val = 0x141400,
+	.status_reg = 0x1c,
+	.lock_bit = 16,
+
+	.l_val = 0x20,
+	.user_val = 0x100109,
+	.min_rate = 556800000UL,
+	.max_rate = 902400000UL,
+};
+
+static const struct of_device_id qcom_hfpll_match_table[] = {
+	{ .compatible = "qcom,msm8976-hfpll-a53", .data = &msm8976_a53 },
+	{ .compatible = "qcom,msm8976-hfpll-a72", .data = &msm8976_a72 },
+	{ .compatible = "qcom,msm8976-hfpll-cci", .data = &msm8976_cci },
+	{ .compatible = "qcom,qcs404-hfpll", .data = &qcs404 },
+	/* Deprecated in bindings */
+	{ .compatible = "qcom,hfpll", .data = &qcs404 },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, qcom_hfpll_match_table);
+
+static const struct regmap_config hfpll_regmap_config = {
+	.reg_bits	= 32,
+	.reg_stride	= 4,
+	.val_bits	= 32,
+	.max_register	= 0x30,
+};
+
+static int qcom_hfpll_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	void __iomem *base;
+	struct regmap *regmap;
+	struct clk_hfpll *h;
+	struct clk_init_data init = {
+		.num_parents = 1,
+		.ops = &clk_ops_hfpll,
+		/*
+		 * rather than marking the clock critical and forcing the clock
+		 * to be always enabled, we make sure that the clock is not
+		 * disabled: the firmware remains responsible of enabling this
+		 * clock (for more info check the commit log)
+		 */
+		.flags = CLK_IGNORE_UNUSED,
+	};
+	int ret;
+	struct clk_parent_data pdata = { .index = 0 };
+
+	h = devm_kzalloc(dev, sizeof(*h), GFP_KERNEL);
+	if (!h)
+		return -ENOMEM;
+
+	base = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	regmap = devm_regmap_init_mmio(&pdev->dev, base, &hfpll_regmap_config);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	if (of_property_read_string_index(dev->of_node, "clock-output-names",
+					  0, &init.name))
+		return -ENODEV;
+
+	init.parent_data = &pdata;
+
+	h->d = of_device_get_match_data(&pdev->dev);
+	h->clkr.hw.init = &init;
+	spin_lock_init(&h->lock);
+
+	ret = devm_clk_register_regmap(dev, &h->clkr);
+	if (ret) {
+		dev_err(dev, "failed to register regmap clock: %d\n", ret);
+		return ret;
+	}
+
+	return devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get,
+					   &h->clkr.hw);
+}
+
+static struct platform_driver qcom_hfpll_driver = {
+	.probe		= qcom_hfpll_probe,
+	.driver		= {
+		.name	= "qcom-hfpll",
+		.of_match_table = qcom_hfpll_match_table,
+	},
+};
+module_platform_driver(qcom_hfpll_driver);
+
+MODULE_DESCRIPTION("QCOM HFPLL Clock Driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:qcom-hfpll");