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, 272 insertions, 0 deletions

diff --git a/drivers/clk/ti/composite.c b/drivers/clk/ti/composite.c
new file mode 100644
index 000000000..83c3592cd
--- /dev/null
+++ b/drivers/clk/ti/composite.c
@@ -0,0 +1,272 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * TI composite clock support
+ *
+ * Copyright (C) 2013 Texas Instruments, Inc.
+ *
+ * Tero Kristo <t-kristo@ti.com>
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/clk/ti.h>
+#include <linux/list.h>
+
+#include "clock.h"
+
+#undef pr_fmt
+#define pr_fmt(fmt) "%s: " fmt, __func__
+
+static unsigned long ti_composite_recalc_rate(struct clk_hw *hw,
+					      unsigned long parent_rate)
+{
+	return ti_clk_divider_ops.recalc_rate(hw, parent_rate);
+}
+
+static int ti_composite_determine_rate(struct clk_hw *hw,
+				       struct clk_rate_request *req)
+{
+	return -EINVAL;
+}
+
+static int ti_composite_set_rate(struct clk_hw *hw, unsigned long rate,
+				 unsigned long parent_rate)
+{
+	return -EINVAL;
+}
+
+static const struct clk_ops ti_composite_divider_ops = {
+	.recalc_rate	= &ti_composite_recalc_rate,
+	.determine_rate	= &ti_composite_determine_rate,
+	.set_rate	= &ti_composite_set_rate,
+};
+
+static const struct clk_ops ti_composite_gate_ops = {
+	.enable		= &omap2_dflt_clk_enable,
+	.disable	= &omap2_dflt_clk_disable,
+	.is_enabled	= &omap2_dflt_clk_is_enabled,
+};
+
+struct component_clk {
+	int num_parents;
+	struct clk_parent_data *parent_data;
+	struct device_node *node;
+	int type;
+	struct clk_hw *hw;
+	struct list_head link;
+};
+
+static const char * const component_clk_types[] __initconst = {
+	"gate", "divider", "mux"
+};
+
+static LIST_HEAD(component_clks);
+
+static struct device_node *_get_component_node(struct device_node *node, int i)
+{
+	int rc;
+	struct of_phandle_args clkspec;
+
+	rc = of_parse_phandle_with_args(node, "clocks", "#clock-cells", i,
+					&clkspec);
+	if (rc)
+		return NULL;
+
+	return clkspec.np;
+}
+
+static struct component_clk *_lookup_component(struct device_node *node)
+{
+	struct component_clk *comp;
+
+	list_for_each_entry(comp, &component_clks, link) {
+		if (comp->node == node)
+			return comp;
+	}
+	return NULL;
+}
+
+struct clk_hw_omap_comp {
+	struct clk_hw hw;
+	struct device_node *comp_nodes[CLK_COMPONENT_TYPE_MAX];
+	struct component_clk *comp_clks[CLK_COMPONENT_TYPE_MAX];
+};
+
+static inline struct clk_hw *_get_hw(struct clk_hw_omap_comp *clk, int idx)
+{
+	if (!clk)
+		return NULL;
+
+	if (!clk->comp_clks[idx])
+		return NULL;
+
+	return clk->comp_clks[idx]->hw;
+}
+
+#define to_clk_hw_comp(_hw) container_of(_hw, struct clk_hw_omap_comp, hw)
+
+static void __init _register_composite(void *user,
+				       struct device_node *node)
+{
+	struct clk_hw *hw = user;
+	struct clk *clk;
+	struct clk_hw_omap_comp *cclk = to_clk_hw_comp(hw);
+	struct component_clk *comp;
+	int num_parents = 0;
+	struct clk_parent_data *parent_data = NULL;
+	const char *name;
+	int i;
+	int ret;
+
+	/* Check for presence of each component clock */
+	for (i = 0; i < CLK_COMPONENT_TYPE_MAX; i++) {
+		if (!cclk->comp_nodes[i])
+			continue;
+
+		comp = _lookup_component(cclk->comp_nodes[i]);
+		if (!comp) {
+			pr_debug("component %s not ready for %pOFn, retry\n",
+				 cclk->comp_nodes[i]->name, node);
+			if (!ti_clk_retry_init(node, hw,
+					       _register_composite))
+				return;
+
+			goto cleanup;
+		}
+		if (cclk->comp_clks[comp->type] != NULL) {
+			pr_err("duplicate component types for %pOFn (%s)!\n",
+			       node, component_clk_types[comp->type]);
+			goto cleanup;
+		}
+
+		cclk->comp_clks[comp->type] = comp;
+
+		/* Mark this node as found */
+		cclk->comp_nodes[i] = NULL;
+	}
+
+	/* All components exists, proceed with registration */
+	for (i = CLK_COMPONENT_TYPE_MAX - 1; i >= 0; i--) {
+		comp = cclk->comp_clks[i];
+		if (!comp)
+			continue;
+		if (comp->num_parents) {
+			num_parents = comp->num_parents;
+			parent_data = comp->parent_data;
+			break;
+		}
+	}
+
+	if (!num_parents) {
+		pr_err("%s: no parents found for %pOFn!\n", __func__, node);
+		goto cleanup;
+	}
+
+	name = ti_dt_clk_name(node);
+	clk = clk_register_composite_pdata(NULL, name,
+				     parent_data, num_parents,
+				     _get_hw(cclk, CLK_COMPONENT_TYPE_MUX),
+				     &ti_clk_mux_ops,
+				     _get_hw(cclk, CLK_COMPONENT_TYPE_DIVIDER),
+				     &ti_composite_divider_ops,
+				     _get_hw(cclk, CLK_COMPONENT_TYPE_GATE),
+				     &ti_composite_gate_ops, 0);
+
+	if (!IS_ERR(clk)) {
+		ret = ti_clk_add_alias(clk, name);
+		if (ret) {
+			clk_unregister(clk);
+			goto cleanup;
+		}
+		of_clk_add_provider(node, of_clk_src_simple_get, clk);
+	}
+
+cleanup:
+	/* Free component clock list entries */
+	for (i = 0; i < CLK_COMPONENT_TYPE_MAX; i++) {
+		if (!cclk->comp_clks[i])
+			continue;
+		list_del(&cclk->comp_clks[i]->link);
+		kfree(cclk->comp_clks[i]->parent_data);
+		kfree(cclk->comp_clks[i]);
+	}
+
+	kfree(cclk);
+}
+
+static void __init of_ti_composite_clk_setup(struct device_node *node)
+{
+	unsigned int num_clks;
+	int i;
+	struct clk_hw_omap_comp *cclk;
+
+	/* Number of component clocks to be put inside this clock */
+	num_clks = of_clk_get_parent_count(node);
+
+	if (!num_clks) {
+		pr_err("composite clk %pOFn must have component(s)\n", node);
+		return;
+	}
+
+	cclk = kzalloc_obj(*cclk);
+	if (!cclk)
+		return;
+
+	/* Get device node pointers for each component clock */
+	for (i = 0; i < num_clks; i++)
+		cclk->comp_nodes[i] = _get_component_node(node, i);
+
+	_register_composite(&cclk->hw, node);
+}
+CLK_OF_DECLARE(ti_composite_clock, "ti,composite-clock",
+	       of_ti_composite_clk_setup);
+
+/**
+ * ti_clk_add_component - add a component clock to the pool
+ * @node: device node of the component clock
+ * @hw: hardware clock definition for the component clock
+ * @type: type of the component clock
+ *
+ * Adds a component clock to the list of available components, so that
+ * it can be registered by a composite clock.
+ */
+int __init ti_clk_add_component(struct device_node *node, struct clk_hw *hw,
+				int type)
+{
+	unsigned int num_parents;
+	struct clk_parent_data *parent_data;
+	struct component_clk *clk;
+	unsigned int i;
+
+	num_parents = of_clk_get_parent_count(node);
+
+	if (!num_parents) {
+		pr_err("component-clock %pOFn must have parent(s)\n", node);
+		return -EINVAL;
+	}
+
+	parent_data = kzalloc_objs(*parent_data, num_parents);
+	if (!parent_data)
+		return -ENOMEM;
+
+	for (i = 0; i < num_parents; i++)
+		parent_data[i].index = i;
+
+	clk = kzalloc_obj(*clk);
+	if (!clk) {
+		kfree(parent_data);
+		return -ENOMEM;
+	}
+
+	clk->num_parents = num_parents;
+	clk->parent_data = parent_data;
+	clk->hw = hw;
+	clk->node = node;
+	clk->type = type;
+	list_add(&clk->link, &component_clks);
+
+	return 0;
+}