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/surface_temp.c | 235 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 235 insertions(+) create mode 100644 drivers/hwmon/surface_temp.c (limited to 'drivers/hwmon/surface_temp.c') diff --git a/drivers/hwmon/surface_temp.c b/drivers/hwmon/surface_temp.c new file mode 100644 index 000000000..cd21f331f --- /dev/null +++ b/drivers/hwmon/surface_temp.c @@ -0,0 +1,235 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Thermal sensor subsystem driver for Surface System Aggregator Module (SSAM). + * + * Copyright (C) 2022-2023 Maximilian Luz + */ + +#include +#include +#include +#include +#include + +#include +#include + +/* -- SAM interface. -------------------------------------------------------- */ + +/* + * Available sensors are indicated by a 16-bit bitfield, where a 1 marks the + * presence of a sensor. So we have at most 16 possible sensors/channels. + */ +#define SSAM_TMP_SENSOR_MAX_COUNT 16 + +/* + * All names observed so far are 6 characters long, but there's only + * zeros after the name, so perhaps they can be longer. This number reflects + * the maximum zero-padded space observed in the returned buffer. + */ +#define SSAM_TMP_SENSOR_NAME_LENGTH 18 + +struct ssam_tmp_get_name_rsp { + __le16 unknown1; + char unknown2; + char name[SSAM_TMP_SENSOR_NAME_LENGTH]; +} __packed; + +static_assert(sizeof(struct ssam_tmp_get_name_rsp) == 21); + +SSAM_DEFINE_SYNC_REQUEST_CL_R(__ssam_tmp_get_available_sensors, __le16, { + .target_category = SSAM_SSH_TC_TMP, + .command_id = 0x04, +}); + +SSAM_DEFINE_SYNC_REQUEST_MD_R(__ssam_tmp_get_temperature, __le16, { + .target_category = SSAM_SSH_TC_TMP, + .command_id = 0x01, +}); + +SSAM_DEFINE_SYNC_REQUEST_MD_R(__ssam_tmp_get_name, struct ssam_tmp_get_name_rsp, { + .target_category = SSAM_SSH_TC_TMP, + .command_id = 0x0e, +}); + +static int ssam_tmp_get_available_sensors(struct ssam_device *sdev, s16 *sensors) +{ + __le16 sensors_le; + int status; + + status = __ssam_tmp_get_available_sensors(sdev, &sensors_le); + if (status) + return status; + + *sensors = le16_to_cpu(sensors_le); + return 0; +} + +static int ssam_tmp_get_temperature(struct ssam_device *sdev, u8 iid, long *temperature) +{ + __le16 temp_le; + int status; + + status = __ssam_tmp_get_temperature(sdev->ctrl, sdev->uid.target, iid, &temp_le); + if (status) + return status; + + /* Convert 1/10 °K to 1/1000 °C */ + *temperature = (le16_to_cpu(temp_le) - 2731) * 100L; + return 0; +} + +static int ssam_tmp_get_name(struct ssam_device *sdev, u8 iid, char *buf, size_t buf_len) +{ + struct ssam_tmp_get_name_rsp name_rsp; + int status; + + status = __ssam_tmp_get_name(sdev->ctrl, sdev->uid.target, iid, &name_rsp); + if (status) + return status; + + /* + * This should not fail unless the name in the returned struct is not + * null-terminated or someone changed something in the struct + * definitions above, since our buffer and struct have the same + * capacity by design. So if this fails, log an error message. Since + * the more likely cause is that the returned string isn't + * null-terminated, we might have received garbage (as opposed to just + * an incomplete string), so also fail the function. + */ + status = strscpy(buf, name_rsp.name, buf_len); + if (status < 0) { + dev_err(&sdev->dev, "received non-null-terminated sensor name string\n"); + return status; + } + + return 0; +} + +/* -- Driver.---------------------------------------------------------------- */ + +struct ssam_temp { + struct ssam_device *sdev; + s16 sensors; + char names[SSAM_TMP_SENSOR_MAX_COUNT][SSAM_TMP_SENSOR_NAME_LENGTH]; +}; + +static umode_t ssam_temp_hwmon_is_visible(const void *data, + enum hwmon_sensor_types type, + u32 attr, int channel) +{ + const struct ssam_temp *ssam_temp = data; + + if (!(ssam_temp->sensors & BIT(channel))) + return 0; + + return 0444; +} + +static int ssam_temp_hwmon_read(struct device *dev, + enum hwmon_sensor_types type, + u32 attr, int channel, long *value) +{ + const struct ssam_temp *ssam_temp = dev_get_drvdata(dev); + + return ssam_tmp_get_temperature(ssam_temp->sdev, channel + 1, value); +} + +static int ssam_temp_hwmon_read_string(struct device *dev, + enum hwmon_sensor_types type, + u32 attr, int channel, const char **str) +{ + const struct ssam_temp *ssam_temp = dev_get_drvdata(dev); + + *str = ssam_temp->names[channel]; + return 0; +} + +static const struct hwmon_channel_info * const ssam_temp_hwmon_info[] = { + HWMON_CHANNEL_INFO(chip, + HWMON_C_REGISTER_TZ), + HWMON_CHANNEL_INFO(temp, + HWMON_T_INPUT | HWMON_T_LABEL, + HWMON_T_INPUT | HWMON_T_LABEL, + HWMON_T_INPUT | HWMON_T_LABEL, + HWMON_T_INPUT | HWMON_T_LABEL, + HWMON_T_INPUT | HWMON_T_LABEL, + HWMON_T_INPUT | HWMON_T_LABEL, + HWMON_T_INPUT | HWMON_T_LABEL, + HWMON_T_INPUT | HWMON_T_LABEL, + HWMON_T_INPUT | HWMON_T_LABEL, + HWMON_T_INPUT | HWMON_T_LABEL, + HWMON_T_INPUT | HWMON_T_LABEL, + HWMON_T_INPUT | HWMON_T_LABEL, + HWMON_T_INPUT | HWMON_T_LABEL, + HWMON_T_INPUT | HWMON_T_LABEL, + HWMON_T_INPUT | HWMON_T_LABEL, + HWMON_T_INPUT | HWMON_T_LABEL), + NULL +}; + +static const struct hwmon_ops ssam_temp_hwmon_ops = { + .is_visible = ssam_temp_hwmon_is_visible, + .read = ssam_temp_hwmon_read, + .read_string = ssam_temp_hwmon_read_string, +}; + +static const struct hwmon_chip_info ssam_temp_hwmon_chip_info = { + .ops = &ssam_temp_hwmon_ops, + .info = ssam_temp_hwmon_info, +}; + +static int ssam_temp_probe(struct ssam_device *sdev) +{ + struct ssam_temp *ssam_temp; + struct device *hwmon_dev; + s16 sensors; + int channel; + int status; + + status = ssam_tmp_get_available_sensors(sdev, &sensors); + if (status) + return status; + + ssam_temp = devm_kzalloc(&sdev->dev, sizeof(*ssam_temp), GFP_KERNEL); + if (!ssam_temp) + return -ENOMEM; + + ssam_temp->sdev = sdev; + ssam_temp->sensors = sensors; + + /* Retrieve the name for each available sensor. */ + for (channel = 0; channel < SSAM_TMP_SENSOR_MAX_COUNT; channel++) { + if (!(sensors & BIT(channel))) + continue; + + status = ssam_tmp_get_name(sdev, channel + 1, ssam_temp->names[channel], + SSAM_TMP_SENSOR_NAME_LENGTH); + if (status) + return status; + } + + hwmon_dev = devm_hwmon_device_register_with_info(&sdev->dev, "surface_thermal", ssam_temp, + &ssam_temp_hwmon_chip_info, NULL); + return PTR_ERR_OR_ZERO(hwmon_dev); +} + +static const struct ssam_device_id ssam_temp_match[] = { + { SSAM_SDEV(TMP, SAM, 0x00, 0x02) }, + { }, +}; +MODULE_DEVICE_TABLE(ssam, ssam_temp_match); + +static struct ssam_device_driver ssam_temp = { + .probe = ssam_temp_probe, + .match_table = ssam_temp_match, + .driver = { + .name = "surface_temp", + .probe_type = PROBE_PREFER_ASYNCHRONOUS, + }, +}; +module_ssam_device_driver(ssam_temp); + +MODULE_AUTHOR("Maximilian Luz "); +MODULE_DESCRIPTION("Thermal sensor subsystem driver for Surface System Aggregator Module"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1