From 93de2a6a4b91b72607136dd656edf03fb399d27f Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 23 Sep 2026 09:37:21 -0700 Subject: KVM: SEV: Do cache maintenance on the source VM during intra-host migration 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 Signed-off-by: Sean Christopherson Message-ID: <20260923163721.1584779-3-seanjc@google.com> Signed-off-by: Paolo Bonzini --- drivers/hwmon/max127.c | 333 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 333 insertions(+) create mode 100644 drivers/hwmon/max127.c (limited to 'drivers/hwmon/max127.c') diff --git a/drivers/hwmon/max127.c b/drivers/hwmon/max127.c new file mode 100644 index 000000000..b294e86d5 --- /dev/null +++ b/drivers/hwmon/max127.c @@ -0,0 +1,333 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Hardware monitoring driver for MAX127. + * + * Copyright (c) 2020 Facebook Inc. + */ + +#include +#include +#include +#include +#include + +/* + * MAX127 Control Byte. Refer to MAX127 datasheet, Table 1 "Control-Byte + * Format" for details. + */ +#define MAX127_CTRL_START BIT(7) +#define MAX127_CTRL_SEL_SHIFT 4 +#define MAX127_CTRL_RNG BIT(3) +#define MAX127_CTRL_BIP BIT(2) +#define MAX127_CTRL_PD1 BIT(1) +#define MAX127_CTRL_PD0 BIT(0) + +#define MAX127_NUM_CHANNELS 8 +#define MAX127_SET_CHANNEL(ch) (((ch) & 7) << MAX127_CTRL_SEL_SHIFT) + +/* + * MAX127 channel input ranges. Refer to MAX127 datasheet, Table 3 "Range + * and Polarity Selection" for details. + */ +#define MAX127_FULL_RANGE 10000 /* 10V */ +#define MAX127_HALF_RANGE 5000 /* 5V */ + +/* + * MAX127 returns 2 bytes at read: + * - the first byte contains data[11:4]. + * - the second byte contains data[3:0] (MSB) and 4 dummy 0s (LSB). + * Refer to MAX127 datasheet, "Read a Conversion (Read Cycle)" section + * for details. + */ +#define MAX127_DATA_LEN 2 +#define MAX127_DATA_SHIFT 4 + +#define MAX127_SIGN_BIT BIT(11) + +struct max127_data { + struct i2c_client *client; + u8 ctrl_byte[MAX127_NUM_CHANNELS]; +}; + +static int max127_select_channel(struct i2c_client *client, u8 ctrl_byte) +{ + int status; + struct i2c_msg msg = { + .addr = client->addr, + .flags = 0, + .len = sizeof(ctrl_byte), + .buf = &ctrl_byte, + }; + + status = i2c_transfer(client->adapter, &msg, 1); + if (status < 0) + return status; + if (status != 1) + return -EIO; + + return 0; +} + +static int max127_read_channel(struct i2c_client *client, long *val) +{ + int status; + u8 i2c_data[MAX127_DATA_LEN]; + struct i2c_msg msg = { + .addr = client->addr, + .flags = I2C_M_RD, + .len = sizeof(i2c_data), + .buf = i2c_data, + }; + + status = i2c_transfer(client->adapter, &msg, 1); + if (status < 0) + return status; + if (status != 1) + return -EIO; + + *val = (i2c_data[1] >> MAX127_DATA_SHIFT) | + ((u16)i2c_data[0] << MAX127_DATA_SHIFT); + return 0; +} + +static long max127_process_raw(u8 ctrl_byte, long raw) +{ + long scale, weight; + + /* + * MAX127's data coding is binary in unipolar mode with 1 LSB = + * (Full-Scale/4096) and two’s complement binary in bipolar mode + * with 1 LSB = [(2 x |FS|)/4096]. + * Refer to MAX127 datasheet, "Transfer Function" section for + * details. + */ + scale = (ctrl_byte & MAX127_CTRL_RNG) ? MAX127_FULL_RANGE : + MAX127_HALF_RANGE; + if (ctrl_byte & MAX127_CTRL_BIP) { + weight = (raw & MAX127_SIGN_BIT); + raw &= ~MAX127_SIGN_BIT; + raw -= weight; + raw *= 2; + } + + return raw * scale / 4096; +} + +static int max127_read_input(struct max127_data *data, int channel, long *val) +{ + long raw; + int status; + struct i2c_client *client = data->client; + u8 ctrl_byte = data->ctrl_byte[channel]; + + status = max127_select_channel(client, ctrl_byte); + if (status) + return status; + + status = max127_read_channel(client, &raw); + if (status) + return status; + + *val = max127_process_raw(ctrl_byte, raw); + return 0; +} + +static int max127_read_min(struct max127_data *data, int channel, long *val) +{ + u8 rng_bip = (data->ctrl_byte[channel] >> 2) & 3; + static const int min_input_map[4] = { + 0, /* RNG=0, BIP=0 */ + -MAX127_HALF_RANGE, /* RNG=0, BIP=1 */ + 0, /* RNG=1, BIP=0 */ + -MAX127_FULL_RANGE, /* RNG=1, BIP=1 */ + }; + + *val = min_input_map[rng_bip]; + return 0; +} + +static int max127_read_max(struct max127_data *data, int channel, long *val) +{ + u8 rng_bip = (data->ctrl_byte[channel] >> 2) & 3; + static const int max_input_map[4] = { + MAX127_HALF_RANGE, /* RNG=0, BIP=0 */ + MAX127_HALF_RANGE, /* RNG=0, BIP=1 */ + MAX127_FULL_RANGE, /* RNG=1, BIP=0 */ + MAX127_FULL_RANGE, /* RNG=1, BIP=1 */ + }; + + *val = max_input_map[rng_bip]; + return 0; +} + +static int max127_write_min(struct max127_data *data, int channel, long val) +{ + u8 ctrl; + + ctrl = data->ctrl_byte[channel]; + if (val <= -MAX127_FULL_RANGE) { + ctrl |= (MAX127_CTRL_RNG | MAX127_CTRL_BIP); + } else if (val < 0) { + ctrl |= MAX127_CTRL_BIP; + ctrl &= ~MAX127_CTRL_RNG; + } else { + ctrl &= ~MAX127_CTRL_BIP; + } + data->ctrl_byte[channel] = ctrl; + return 0; +} + +static int max127_write_max(struct max127_data *data, int channel, long val) +{ + if (val >= MAX127_FULL_RANGE) + data->ctrl_byte[channel] |= MAX127_CTRL_RNG; + else + data->ctrl_byte[channel] &= ~MAX127_CTRL_RNG; + return 0; +} + +static umode_t max127_is_visible(const void *_data, + enum hwmon_sensor_types type, + u32 attr, int channel) +{ + if (type == hwmon_in) { + switch (attr) { + case hwmon_in_input: + return 0444; + + case hwmon_in_min: + case hwmon_in_max: + return 0644; + + default: + break; + } + } + + return 0; +} + +static int max127_read(struct device *dev, enum hwmon_sensor_types type, + u32 attr, int channel, long *val) +{ + int status; + struct max127_data *data = dev_get_drvdata(dev); + + if (type != hwmon_in) + return -EOPNOTSUPP; + + switch (attr) { + case hwmon_in_input: + status = max127_read_input(data, channel, val); + break; + + case hwmon_in_min: + status = max127_read_min(data, channel, val); + break; + + case hwmon_in_max: + status = max127_read_max(data, channel, val); + break; + + default: + status = -EOPNOTSUPP; + break; + } + + return status; +} + +static int max127_write(struct device *dev, enum hwmon_sensor_types type, + u32 attr, int channel, long val) +{ + int status; + struct max127_data *data = dev_get_drvdata(dev); + + if (type != hwmon_in) + return -EOPNOTSUPP; + + switch (attr) { + case hwmon_in_min: + status = max127_write_min(data, channel, val); + break; + + case hwmon_in_max: + status = max127_write_max(data, channel, val); + break; + + default: + status = -EOPNOTSUPP; + break; + } + + return status; +} + +static const struct hwmon_ops max127_hwmon_ops = { + .is_visible = max127_is_visible, + .read = max127_read, + .write = max127_write, +}; + +static const struct hwmon_channel_info * const max127_info[] = { + HWMON_CHANNEL_INFO(in, + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX, + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX, + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX, + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX, + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX, + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX, + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX, + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX), + NULL, +}; + +static const struct hwmon_chip_info max127_chip_info = { + .ops = &max127_hwmon_ops, + .info = max127_info, +}; + +static int max127_probe(struct i2c_client *client) +{ + int i; + struct device *hwmon_dev; + struct max127_data *data; + struct device *dev = &client->dev; + + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + data->client = client; + for (i = 0; i < ARRAY_SIZE(data->ctrl_byte); i++) + data->ctrl_byte[i] = (MAX127_CTRL_START | + MAX127_SET_CHANNEL(i)); + + hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, + data, + &max127_chip_info, + NULL); + + return PTR_ERR_OR_ZERO(hwmon_dev); +} + +static const struct i2c_device_id max127_id[] = { + { .name = "max127" }, + { } +}; +MODULE_DEVICE_TABLE(i2c, max127_id); + +static struct i2c_driver max127_driver = { + .driver = { + .name = "max127", + }, + .probe = max127_probe, + .id_table = max127_id, +}; + +module_i2c_driver(max127_driver); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Mike Choi "); +MODULE_AUTHOR("Tao Ren "); +MODULE_DESCRIPTION("MAX127 Hardware Monitoring driver"); -- cgit v1.3.1