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, 106 insertions, 0 deletions

diff --git a/drivers/clk/qcom/clk-regmap.c b/drivers/clk/qcom/clk-regmap.c
new file mode 100644
index 000000000..92ac4e0d7
--- /dev/null
+++ b/drivers/clk/qcom/clk-regmap.c
@@ -0,0 +1,106 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2014, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/device.h>
+#include <linux/clk-provider.h>
+#include <linux/regmap.h>
+#include <linux/export.h>
+
+#include "clk-regmap.h"
+
+/**
+ * clk_is_enabled_regmap - standard is_enabled() for regmap users
+ *
+ * @hw: clk to operate on
+ *
+ * Clocks that use regmap for their register I/O can set the
+ * enable_reg and enable_mask fields in their struct clk_regmap and then use
+ * this as their is_enabled operation, saving some code.
+ */
+int clk_is_enabled_regmap(struct clk_hw *hw)
+{
+	struct clk_regmap *rclk = to_clk_regmap(hw);
+	unsigned int val;
+	int ret;
+
+	ret = regmap_read(rclk->regmap, rclk->enable_reg, &val);
+	if (ret != 0)
+		return ret;
+
+	if (rclk->enable_is_inverted)
+		return (val & rclk->enable_mask) == 0;
+	else
+		return (val & rclk->enable_mask) != 0;
+}
+EXPORT_SYMBOL_GPL(clk_is_enabled_regmap);
+
+/**
+ * clk_enable_regmap - standard enable() for regmap users
+ *
+ * @hw: clk to operate on
+ *
+ * Clocks that use regmap for their register I/O can set the
+ * enable_reg and enable_mask fields in their struct clk_regmap and then use
+ * this as their enable() operation, saving some code.
+ */
+int clk_enable_regmap(struct clk_hw *hw)
+{
+	struct clk_regmap *rclk = to_clk_regmap(hw);
+	unsigned int val;
+
+	if (rclk->enable_is_inverted)
+		val = 0;
+	else
+		val = rclk->enable_mask;
+
+	return regmap_update_bits(rclk->regmap, rclk->enable_reg,
+				  rclk->enable_mask, val);
+}
+EXPORT_SYMBOL_GPL(clk_enable_regmap);
+
+/**
+ * clk_disable_regmap - standard disable() for regmap users
+ *
+ * @hw: clk to operate on
+ *
+ * Clocks that use regmap for their register I/O can set the
+ * enable_reg and enable_mask fields in their struct clk_regmap and then use
+ * this as their disable() operation, saving some code.
+ */
+void clk_disable_regmap(struct clk_hw *hw)
+{
+	struct clk_regmap *rclk = to_clk_regmap(hw);
+	unsigned int val;
+
+	if (rclk->enable_is_inverted)
+		val = rclk->enable_mask;
+	else
+		val = 0;
+
+	regmap_update_bits(rclk->regmap, rclk->enable_reg, rclk->enable_mask,
+			   val);
+}
+EXPORT_SYMBOL_GPL(clk_disable_regmap);
+
+/**
+ * devm_clk_register_regmap - register a clk_regmap clock
+ *
+ * @dev: reference to the caller's device
+ * @rclk: clk to operate on
+ *
+ * Clocks that use regmap for their register I/O should register their
+ * clk_regmap struct via this function so that the regmap is initialized
+ * and so that the clock is registered with the common clock framework.
+ */
+int devm_clk_register_regmap(struct device *dev, struct clk_regmap *rclk)
+{
+	if (dev && dev_get_regmap(dev, NULL))
+		rclk->regmap = dev_get_regmap(dev, NULL);
+	else if (dev && dev->parent)
+		rclk->regmap = dev_get_regmap(dev->parent, NULL);
+
+	return devm_clk_hw_register(dev, &rclk->hw);
+}
+EXPORT_SYMBOL_GPL(devm_clk_register_regmap);