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/net/netdevsim/health.c | 231 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 231 insertions(+) create mode 100644 drivers/net/netdevsim/health.c (limited to 'drivers/net/netdevsim/health.c') diff --git a/drivers/net/netdevsim/health.c b/drivers/net/netdevsim/health.c new file mode 100644 index 000000000..3bd0e7a48 --- /dev/null +++ b/drivers/net/netdevsim/health.c @@ -0,0 +1,231 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2019 Mellanox Technologies. All rights reserved */ + +#include +#include +#include +#include + +#include "netdevsim.h" + +static int +nsim_dev_empty_reporter_dump(struct devlink_health_reporter *reporter, + struct devlink_fmsg *fmsg, void *priv_ctx, + struct netlink_ext_ack *extack) +{ + return 0; +} + +static int +nsim_dev_empty_reporter_diagnose(struct devlink_health_reporter *reporter, + struct devlink_fmsg *fmsg, + struct netlink_ext_ack *extack) +{ + return 0; +} + +static const +struct devlink_health_reporter_ops nsim_dev_empty_reporter_ops = { + .name = "empty", + .dump = nsim_dev_empty_reporter_dump, + .diagnose = nsim_dev_empty_reporter_diagnose, +}; + +struct nsim_dev_dummy_reporter_ctx { + char *break_msg; +}; + +static int +nsim_dev_dummy_reporter_recover(struct devlink_health_reporter *reporter, + void *priv_ctx, + struct netlink_ext_ack *extack) +{ + struct nsim_dev_health *health = devlink_health_reporter_priv(reporter); + struct nsim_dev_dummy_reporter_ctx *ctx = priv_ctx; + + if (health->fail_recover) { + /* For testing purposes, user set debugfs fail_recover + * value to true. Fail right away. + */ + NL_SET_ERR_MSG_MOD(extack, "User setup the recover to fail for testing purposes"); + return -EINVAL; + } + if (ctx) { + kfree(health->recovered_break_msg); + health->recovered_break_msg = kstrdup(ctx->break_msg, + GFP_KERNEL); + if (!health->recovered_break_msg) + return -ENOMEM; + } + return 0; +} + +static int nsim_dev_dummy_fmsg_put(struct devlink_fmsg *fmsg, u32 binary_len) +{ + char *binary; + int i; + + devlink_fmsg_bool_pair_put(fmsg, "test_bool", true); + devlink_fmsg_u8_pair_put(fmsg, "test_u8", 1); + devlink_fmsg_u32_pair_put(fmsg, "test_u32", 3); + devlink_fmsg_u64_pair_put(fmsg, "test_u64", 4); + devlink_fmsg_string_pair_put(fmsg, "test_string", "somestring"); + + binary = kmalloc(binary_len, GFP_KERNEL | __GFP_NOWARN); + if (!binary) + return -ENOMEM; + get_random_bytes(binary, binary_len); + devlink_fmsg_binary_pair_put(fmsg, "test_binary", binary, binary_len); + kfree(binary); + + devlink_fmsg_pair_nest_start(fmsg, "test_nest"); + devlink_fmsg_obj_nest_start(fmsg); + devlink_fmsg_bool_pair_put(fmsg, "nested_test_bool", false); + devlink_fmsg_u8_pair_put(fmsg, "nested_test_u8", false); + devlink_fmsg_obj_nest_end(fmsg); + devlink_fmsg_pair_nest_end(fmsg); + devlink_fmsg_arr_pair_nest_end(fmsg); + devlink_fmsg_arr_pair_nest_start(fmsg, "test_u32_array"); + + for (i = 0; i < 10; i++) + devlink_fmsg_u32_put(fmsg, i); + devlink_fmsg_arr_pair_nest_end(fmsg); + devlink_fmsg_arr_pair_nest_start(fmsg, "test_array_of_objects"); + + for (i = 0; i < 10; i++) { + devlink_fmsg_obj_nest_start(fmsg); + devlink_fmsg_bool_pair_put(fmsg, "in_array_nested_test_bool", + false); + devlink_fmsg_u8_pair_put(fmsg, "in_array_nested_test_u8", i); + devlink_fmsg_obj_nest_end(fmsg); + } + devlink_fmsg_arr_pair_nest_end(fmsg); + + return 0; +} + +static int +nsim_dev_dummy_reporter_dump(struct devlink_health_reporter *reporter, + struct devlink_fmsg *fmsg, void *priv_ctx, + struct netlink_ext_ack *extack) +{ + struct nsim_dev_health *health = devlink_health_reporter_priv(reporter); + struct nsim_dev_dummy_reporter_ctx *ctx = priv_ctx; + + if (ctx) + devlink_fmsg_string_pair_put(fmsg, "break_message", ctx->break_msg); + + return nsim_dev_dummy_fmsg_put(fmsg, health->binary_len); +} + +static int +nsim_dev_dummy_reporter_diagnose(struct devlink_health_reporter *reporter, + struct devlink_fmsg *fmsg, + struct netlink_ext_ack *extack) +{ + struct nsim_dev_health *health = devlink_health_reporter_priv(reporter); + + if (health->recovered_break_msg) + devlink_fmsg_string_pair_put(fmsg, "recovered_break_message", + health->recovered_break_msg); + + return nsim_dev_dummy_fmsg_put(fmsg, health->binary_len); +} + +static const +struct devlink_health_reporter_ops nsim_dev_dummy_reporter_ops = { + .name = "dummy", + .recover = nsim_dev_dummy_reporter_recover, + .dump = nsim_dev_dummy_reporter_dump, + .diagnose = nsim_dev_dummy_reporter_diagnose, +}; + +static ssize_t nsim_dev_health_break_write(struct file *file, + const char __user *data, + size_t count, loff_t *ppos) +{ + struct nsim_dev_health *health = file->private_data; + struct nsim_dev_dummy_reporter_ctx ctx; + char *break_msg; + int err; + + if (count == 0 || count > PAGE_SIZE) + return -EINVAL; + break_msg = memdup_user_nul(data, count); + if (IS_ERR(break_msg)) + return PTR_ERR(break_msg); + + if (break_msg[count - 1] == '\n') + break_msg[count - 1] = '\0'; + + ctx.break_msg = break_msg; + err = devlink_health_report(health->dummy_reporter, break_msg, &ctx); + if (err) + goto out; + +out: + kfree(break_msg); + return err ?: count; +} + +static const struct file_operations nsim_dev_health_break_fops = { + .open = simple_open, + .write = nsim_dev_health_break_write, + .llseek = generic_file_llseek, + .owner = THIS_MODULE, +}; + +int nsim_dev_health_init(struct nsim_dev *nsim_dev, struct devlink *devlink) +{ + struct nsim_dev_health *health = &nsim_dev->health; + int err; + + health->empty_reporter = + devl_health_reporter_create(devlink, + &nsim_dev_empty_reporter_ops, + health); + if (IS_ERR(health->empty_reporter)) + return PTR_ERR(health->empty_reporter); + + health->dummy_reporter = + devl_health_reporter_create(devlink, + &nsim_dev_dummy_reporter_ops, + health); + if (IS_ERR(health->dummy_reporter)) { + err = PTR_ERR(health->dummy_reporter); + goto err_empty_reporter_destroy; + } + + health->ddir = debugfs_create_dir("health", nsim_dev->ddir); + if (IS_ERR(health->ddir)) { + err = PTR_ERR(health->ddir); + goto err_dummy_reporter_destroy; + } + + health->recovered_break_msg = NULL; + debugfs_create_file("break_health", 0200, health->ddir, health, + &nsim_dev_health_break_fops); + health->binary_len = 16; + debugfs_create_u32("binary_len", 0600, health->ddir, + &health->binary_len); + health->fail_recover = false; + debugfs_create_bool("fail_recover", 0600, health->ddir, + &health->fail_recover); + return 0; + +err_dummy_reporter_destroy: + devl_health_reporter_destroy(health->dummy_reporter); +err_empty_reporter_destroy: + devl_health_reporter_destroy(health->empty_reporter); + return err; +} + +void nsim_dev_health_exit(struct nsim_dev *nsim_dev) +{ + struct nsim_dev_health *health = &nsim_dev->health; + + debugfs_remove_recursive(health->ddir); + kfree(health->recovered_break_msg); + devl_health_reporter_destroy(health->dummy_reporter); + devl_health_reporter_destroy(health->empty_reporter); +} -- cgit v1.3.1