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, 161 insertions, 0 deletions

diff --git a/drivers/reset/reset-qcom-pdc.c b/drivers/reset/reset-qcom-pdc.c
new file mode 100644
index 000000000..ae2b5aba7
--- /dev/null
+++ b/drivers/reset/reset-qcom-pdc.c
@@ -0,0 +1,161 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018 The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/reset-controller.h>
+
+#include <dt-bindings/reset/qcom,sdm845-pdc.h>
+
+#define RPMH_SDM845_PDC_SYNC_RESET	0x100
+#define RPMH_SC7280_PDC_SYNC_RESET	0x1000
+
+struct qcom_pdc_reset_map {
+	u8 bit;
+};
+
+struct qcom_pdc_reset_desc {
+	const struct qcom_pdc_reset_map *resets;
+	size_t num_resets;
+	unsigned int offset;
+};
+
+struct qcom_pdc_reset_data {
+	struct reset_controller_dev rcdev;
+	struct regmap *regmap;
+	const struct qcom_pdc_reset_desc *desc;
+};
+
+static const struct regmap_config pdc_regmap_config = {
+	.name		= "pdc-reset",
+	.reg_bits	= 32,
+	.reg_stride	= 4,
+	.val_bits	= 32,
+	.max_register	= 0x20000,
+};
+
+static const struct qcom_pdc_reset_map sdm845_pdc_resets[] = {
+	[PDC_APPS_SYNC_RESET] = {0},
+	[PDC_SP_SYNC_RESET] = {1},
+	[PDC_AUDIO_SYNC_RESET] = {2},
+	[PDC_SENSORS_SYNC_RESET] = {3},
+	[PDC_AOP_SYNC_RESET] = {4},
+	[PDC_DEBUG_SYNC_RESET] = {5},
+	[PDC_GPU_SYNC_RESET] = {6},
+	[PDC_DISPLAY_SYNC_RESET] = {7},
+	[PDC_COMPUTE_SYNC_RESET] = {8},
+	[PDC_MODEM_SYNC_RESET] = {9},
+};
+
+static const struct qcom_pdc_reset_desc sdm845_pdc_reset_desc = {
+	.resets = sdm845_pdc_resets,
+	.num_resets = ARRAY_SIZE(sdm845_pdc_resets),
+	.offset = RPMH_SDM845_PDC_SYNC_RESET,
+};
+
+static const struct qcom_pdc_reset_map sc7280_pdc_resets[] = {
+	[PDC_APPS_SYNC_RESET] = {0},
+	[PDC_SP_SYNC_RESET] = {1},
+	[PDC_AUDIO_SYNC_RESET] = {2},
+	[PDC_SENSORS_SYNC_RESET] = {3},
+	[PDC_AOP_SYNC_RESET] = {4},
+	[PDC_DEBUG_SYNC_RESET] = {5},
+	[PDC_GPU_SYNC_RESET] = {6},
+	[PDC_DISPLAY_SYNC_RESET] = {7},
+	[PDC_COMPUTE_SYNC_RESET] = {8},
+	[PDC_MODEM_SYNC_RESET] = {9},
+	[PDC_WLAN_RF_SYNC_RESET] = {10},
+	[PDC_WPSS_SYNC_RESET] = {11},
+};
+
+static const struct qcom_pdc_reset_desc sc7280_pdc_reset_desc = {
+	.resets = sc7280_pdc_resets,
+	.num_resets = ARRAY_SIZE(sc7280_pdc_resets),
+	.offset = RPMH_SC7280_PDC_SYNC_RESET,
+};
+
+static inline struct qcom_pdc_reset_data *to_qcom_pdc_reset_data(
+				struct reset_controller_dev *rcdev)
+{
+	return container_of(rcdev, struct qcom_pdc_reset_data, rcdev);
+}
+
+static int qcom_pdc_control_assert(struct reset_controller_dev *rcdev,
+					unsigned long idx)
+{
+	struct qcom_pdc_reset_data *data = to_qcom_pdc_reset_data(rcdev);
+	u32 mask = BIT(data->desc->resets[idx].bit);
+
+	return regmap_update_bits(data->regmap, data->desc->offset, mask, mask);
+}
+
+static int qcom_pdc_control_deassert(struct reset_controller_dev *rcdev,
+					unsigned long idx)
+{
+	struct qcom_pdc_reset_data *data = to_qcom_pdc_reset_data(rcdev);
+	u32 mask = BIT(data->desc->resets[idx].bit);
+
+	return regmap_update_bits(data->regmap, data->desc->offset, mask, 0);
+}
+
+static const struct reset_control_ops qcom_pdc_reset_ops = {
+	.assert = qcom_pdc_control_assert,
+	.deassert = qcom_pdc_control_deassert,
+};
+
+static int qcom_pdc_reset_probe(struct platform_device *pdev)
+{
+	const struct qcom_pdc_reset_desc *desc;
+	struct qcom_pdc_reset_data *data;
+	struct device *dev = &pdev->dev;
+	void __iomem *base;
+
+	desc = device_get_match_data(&pdev->dev);
+	if (!desc)
+		return -EINVAL;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->desc = desc;
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	data->regmap = devm_regmap_init_mmio(dev, base, &pdc_regmap_config);
+	if (IS_ERR(data->regmap)) {
+		dev_err(dev, "Unable to initialize regmap\n");
+		return PTR_ERR(data->regmap);
+	}
+
+	data->rcdev.owner = THIS_MODULE;
+	data->rcdev.ops = &qcom_pdc_reset_ops;
+	data->rcdev.nr_resets = desc->num_resets;
+	data->rcdev.of_node = dev->of_node;
+
+	return devm_reset_controller_register(dev, &data->rcdev);
+}
+
+static const struct of_device_id qcom_pdc_reset_of_match[] = {
+	{ .compatible = "qcom,sc7280-pdc-global", .data = &sc7280_pdc_reset_desc },
+	{ .compatible = "qcom,sdm845-pdc-global", .data = &sdm845_pdc_reset_desc },
+	{}
+};
+MODULE_DEVICE_TABLE(of, qcom_pdc_reset_of_match);
+
+static struct platform_driver qcom_pdc_reset_driver = {
+	.probe = qcom_pdc_reset_probe,
+	.driver = {
+		.name = "qcom_pdc_reset",
+		.of_match_table = qcom_pdc_reset_of_match,
+	},
+};
+module_platform_driver(qcom_pdc_reset_driver);
+
+MODULE_DESCRIPTION("Qualcomm PDC Reset Driver");
+MODULE_LICENSE("GPL v2");