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, 113 insertions, 0 deletions

diff --git a/drivers/clk/sprd/common.c b/drivers/clk/sprd/common.c
new file mode 100644
index 000000000..0f2181617
--- /dev/null
+++ b/drivers/clk/sprd/common.c
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Spreadtrum clock infrastructure
+//
+// Copyright (C) 2017 Spreadtrum, Inc.
+// Author: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
+
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#include "common.h"
+
+static const struct regmap_config sprdclk_regmap_config = {
+	.reg_bits	= 32,
+	.reg_stride	= 4,
+	.val_bits	= 32,
+	.fast_io	= true,
+};
+
+static void sprd_clk_set_regmap(const struct sprd_clk_desc *desc,
+			 struct regmap *regmap)
+{
+	int i;
+	struct sprd_clk_common *cclk;
+
+	for (i = 0; i < desc->num_clk_clks; i++) {
+		cclk = desc->clk_clks[i];
+		if (!cclk)
+			continue;
+
+		cclk->regmap = regmap;
+	}
+}
+
+int sprd_clk_regmap_init(struct platform_device *pdev,
+			 const struct sprd_clk_desc *desc)
+{
+	void __iomem *base;
+	struct device *dev = &pdev->dev;
+	struct device_node *node = dev->of_node, *np;
+	struct regmap *regmap;
+	struct resource *res;
+	struct regmap_config reg_config = sprdclk_regmap_config;
+
+	if (of_property_present(node, "sprd,syscon")) {
+		regmap = syscon_regmap_lookup_by_phandle(node, "sprd,syscon");
+		if (IS_ERR(regmap)) {
+			pr_err("%s: failed to get syscon regmap\n", __func__);
+			return PTR_ERR(regmap);
+		}
+	} else if (of_device_is_compatible(np =	of_get_parent(node), "syscon") ||
+		   (of_node_put(np), 0)) {
+		regmap = device_node_to_regmap(np);
+		of_node_put(np);
+		if (IS_ERR(regmap)) {
+			dev_err(dev, "failed to get regmap from its parent.\n");
+			return PTR_ERR(regmap);
+		}
+	} else {
+		base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+		if (IS_ERR(base))
+			return PTR_ERR(base);
+
+		reg_config.max_register = resource_size(res) - reg_config.reg_stride;
+
+		regmap = devm_regmap_init_mmio(&pdev->dev, base,
+					       &reg_config);
+		if (IS_ERR(regmap)) {
+			pr_err("failed to init regmap\n");
+			return PTR_ERR(regmap);
+		}
+	}
+
+	sprd_clk_set_regmap(desc, regmap);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(sprd_clk_regmap_init);
+
+int sprd_clk_probe(struct device *dev, struct clk_hw_onecell_data *clkhw)
+{
+	int i, ret;
+	struct clk_hw *hw;
+
+	for (i = 0; i < clkhw->num; i++) {
+		const char *name;
+
+		hw = clkhw->hws[i];
+		if (!hw)
+			continue;
+
+		name = hw->init->name;
+		ret = devm_clk_hw_register(dev, hw);
+		if (ret) {
+			dev_err(dev, "Couldn't register clock %d - %s\n",
+				i, name);
+			return ret;
+		}
+	}
+
+	ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get, clkhw);
+	if (ret)
+		dev_err(dev, "Failed to add clock provider\n");
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(sprd_clk_probe);
+
+MODULE_DESCRIPTION("Spreadtrum clock infrastructure");
+MODULE_LICENSE("GPL v2");