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, 134 insertions, 0 deletions

diff --git a/drivers/mfd/ac100.c b/drivers/mfd/ac100.c
new file mode 100644
index 000000000..8f47c392c
--- /dev/null
+++ b/drivers/mfd/ac100.c
@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MFD core driver for X-Powers' AC100 Audio Codec IC
+ *
+ * The AC100 is a highly integrated audio codec and RTC subsystem designed
+ * for mobile applications. It has 3 I2S/PCM interfaces, a 2 channel DAC,
+ * a 2 channel ADC with 5 inputs and a builtin mixer. The RTC subsystem has
+ * 3 clock outputs.
+ *
+ * The audio codec and RTC parts are completely separate, sharing only the
+ * host interface for access to its registers.
+ *
+ * Copyright (2016) Chen-Yu Tsai
+ *
+ * Author: Chen-Yu Tsai <wens@csie.org>
+ */
+
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/ac100.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+#include <linux/sunxi-rsb.h>
+
+static const struct regmap_range ac100_writeable_ranges[] = {
+	regmap_reg_range(AC100_CHIP_AUDIO_RST, AC100_I2S_SR_CTRL),
+	regmap_reg_range(AC100_I2S1_CLK_CTRL, AC100_I2S1_MXR_GAIN),
+	regmap_reg_range(AC100_I2S2_CLK_CTRL, AC100_I2S2_MXR_GAIN),
+	regmap_reg_range(AC100_I2S3_CLK_CTRL, AC100_I2S3_SIG_PATH_CTRL),
+	regmap_reg_range(AC100_ADC_DIG_CTRL, AC100_ADC_VOL_CTRL),
+	regmap_reg_range(AC100_HMIC_CTRL1, AC100_HMIC_STATUS),
+	regmap_reg_range(AC100_DAC_DIG_CTRL, AC100_DAC_MXR_GAIN),
+	regmap_reg_range(AC100_ADC_APC_CTRL, AC100_LINEOUT_CTRL),
+	regmap_reg_range(AC100_ADC_DAP_L_CTRL, AC100_ADC_DAP_OPT),
+	regmap_reg_range(AC100_DAC_DAP_CTRL, AC100_DAC_DAP_OPT),
+	regmap_reg_range(AC100_ADC_DAP_ENA, AC100_DAC_DAP_ENA),
+	regmap_reg_range(AC100_SRC1_CTRL1, AC100_SRC1_CTRL2),
+	regmap_reg_range(AC100_SRC2_CTRL1, AC100_SRC2_CTRL2),
+	regmap_reg_range(AC100_CLK32K_ANALOG_CTRL, AC100_CLKOUT_CTRL3),
+	regmap_reg_range(AC100_RTC_RST, AC100_RTC_UPD),
+	regmap_reg_range(AC100_ALM_INT_ENA, AC100_ALM_INT_STA),
+	regmap_reg_range(AC100_ALM_SEC, AC100_RTC_GP(15)),
+};
+
+static const struct regmap_range ac100_volatile_ranges[] = {
+	regmap_reg_range(AC100_CHIP_AUDIO_RST, AC100_PLL_CTRL2),
+	regmap_reg_range(AC100_HMIC_STATUS, AC100_HMIC_STATUS),
+	regmap_reg_range(AC100_ADC_DAP_L_STA, AC100_ADC_DAP_L_STA),
+	regmap_reg_range(AC100_SRC1_CTRL1, AC100_SRC1_CTRL1),
+	regmap_reg_range(AC100_SRC1_CTRL3, AC100_SRC2_CTRL1),
+	regmap_reg_range(AC100_SRC2_CTRL3, AC100_SRC2_CTRL4),
+	regmap_reg_range(AC100_RTC_RST, AC100_RTC_RST),
+	regmap_reg_range(AC100_RTC_SEC, AC100_ALM_INT_STA),
+	regmap_reg_range(AC100_ALM_SEC, AC100_ALM_UPD),
+};
+
+static const struct regmap_access_table ac100_writeable_table = {
+	.yes_ranges	= ac100_writeable_ranges,
+	.n_yes_ranges	= ARRAY_SIZE(ac100_writeable_ranges),
+};
+
+static const struct regmap_access_table ac100_volatile_table = {
+	.yes_ranges	= ac100_volatile_ranges,
+	.n_yes_ranges	= ARRAY_SIZE(ac100_volatile_ranges),
+};
+
+static const struct regmap_config ac100_regmap_config = {
+	.reg_bits	= 8,
+	.val_bits	= 16,
+	.wr_table	= &ac100_writeable_table,
+	.volatile_table	= &ac100_volatile_table,
+	.max_register	= AC100_RTC_GP(15),
+	.cache_type	= REGCACHE_MAPLE,
+};
+
+static struct mfd_cell ac100_cells[] = {
+	{
+		.name		= "ac100-codec",
+		.of_compatible	= "x-powers,ac100-codec",
+	}, {
+		.name		= "ac100-rtc",
+		.of_compatible	= "x-powers,ac100-rtc",
+	},
+};
+
+static int ac100_rsb_probe(struct sunxi_rsb_device *rdev)
+{
+	struct ac100_dev *ac100;
+	int ret;
+
+	ac100 = devm_kzalloc(&rdev->dev, sizeof(*ac100), GFP_KERNEL);
+	if (!ac100)
+		return -ENOMEM;
+
+	ac100->dev = &rdev->dev;
+	sunxi_rsb_device_set_drvdata(rdev, ac100);
+
+	ac100->regmap = devm_regmap_init_sunxi_rsb(rdev, &ac100_regmap_config);
+	if (IS_ERR(ac100->regmap)) {
+		ret = PTR_ERR(ac100->regmap);
+		dev_err(ac100->dev, "regmap init failed: %d\n", ret);
+		return ret;
+	}
+
+	ret = devm_mfd_add_devices(ac100->dev, PLATFORM_DEVID_NONE, ac100_cells,
+				   ARRAY_SIZE(ac100_cells), NULL, 0, NULL);
+	if (ret) {
+		dev_err(ac100->dev, "failed to add MFD devices: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id ac100_of_match[] = {
+	{ .compatible = "x-powers,ac100" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, ac100_of_match);
+
+static struct sunxi_rsb_driver ac100_rsb_driver = {
+	.driver = {
+		.name	= "ac100",
+		.of_match_table	= of_match_ptr(ac100_of_match),
+	},
+	.probe	= ac100_rsb_probe,
+};
+module_sunxi_rsb_driver(ac100_rsb_driver);
+
+MODULE_DESCRIPTION("Audio codec MFD core driver for AC100");
+MODULE_AUTHOR("Chen-Yu Tsai <wens@csie.org>");
+MODULE_LICENSE("GPL v2");