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 --- lib/kunit/debugfs.c | 242 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 242 insertions(+) create mode 100644 lib/kunit/debugfs.c (limited to 'lib/kunit/debugfs.c') diff --git a/lib/kunit/debugfs.c b/lib/kunit/debugfs.c new file mode 100644 index 000000000..442b2ceb9 --- /dev/null +++ b/lib/kunit/debugfs.c @@ -0,0 +1,242 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2020, Oracle and/or its affiliates. + * Author: Alan Maguire + */ + +#include +#include + +#include +#include + +#include "string-stream.h" +#include "debugfs.h" + +#define KUNIT_DEBUGFS_ROOT "kunit" +#define KUNIT_DEBUGFS_RESULTS "results" +#define KUNIT_DEBUGFS_RUN "run" + +/* + * Create a debugfs representation of test suites: + * + * Path Semantics + * /sys/kernel/debug/kunit//results Show results of last run for + * testsuite + * /sys/kernel/debug/kunit//run Write to this file to trigger + * testsuite to run + * + */ + +static struct dentry *debugfs_rootdir; + +void kunit_debugfs_cleanup(void) +{ + debugfs_remove_recursive(debugfs_rootdir); +} + +void kunit_debugfs_init(void) +{ + if (!debugfs_rootdir) + debugfs_rootdir = debugfs_create_dir(KUNIT_DEBUGFS_ROOT, NULL); +} + +static void debugfs_print_result(struct seq_file *seq, struct string_stream *log) +{ + struct string_stream_fragment *frag_container; + + if (!log) + return; + + /* + * Walk the fragments so we don't need to allocate a temporary + * buffer to hold the entire string. + */ + spin_lock(&log->lock); + list_for_each_entry(frag_container, &log->fragments, node) + seq_printf(seq, "%s", frag_container->fragment); + spin_unlock(&log->lock); +} + +/* + * /sys/kernel/debug/kunit//results shows all results for testsuite. + */ +static int debugfs_print_results(struct seq_file *seq, void *v) +{ + struct kunit_suite *suite = (struct kunit_suite *)seq->private; + enum kunit_status success; + struct kunit_case *test_case; + + if (!suite) + return 0; + + success = kunit_suite_has_succeeded(suite); + + /* Print KTAP header so the debugfs log can be parsed as valid KTAP. */ + seq_puts(seq, "KTAP version 1\n"); + seq_puts(seq, "1..1\n"); + + if (suite->status != KUNIT_SKIPPED) { + /* Print suite header because it is not stored in the test logs. */ + seq_puts(seq, + KUNIT_SUBTEST_INDENT "KTAP version 1\n"); + seq_printf(seq, + KUNIT_SUBTEST_INDENT "# Subtest: %s\n", + suite->name); + seq_printf(seq, + KUNIT_SUBTEST_INDENT "1..%zd\n", + kunit_suite_num_test_cases(suite)); + + kunit_suite_for_each_test_case(suite, test_case) + debugfs_print_result(seq, test_case->log); + } + + debugfs_print_result(seq, suite->log); + + if (suite->status != KUNIT_SKIPPED) + seq_printf(seq, "%s %d %s\n", + kunit_status_to_ok_not_ok(success), 1, suite->name); + else + seq_printf(seq, "%s %d %s # SKIP %s\n", + kunit_status_to_ok_not_ok(success), 1, suite->name, + suite->status_comment); + return 0; +} + +static int debugfs_release(struct inode *inode, struct file *file) +{ + return single_release(inode, file); +} + +static int debugfs_results_open(struct inode *inode, struct file *file) +{ + struct kunit_suite *suite; + + suite = (struct kunit_suite *)inode->i_private; + + return single_open(file, debugfs_print_results, suite); +} + +/* + * Print a usage message to the debugfs "run" file + * (/sys/kernel/debug/kunit//run) if opened. + */ +static int debugfs_print_run(struct seq_file *seq, void *v) +{ + struct kunit_suite *suite = (struct kunit_suite *)seq->private; + + seq_puts(seq, "Write to this file to trigger the test suite to run.\n"); + seq_printf(seq, "usage: echo \"any string\" > /sys/kernel/debugfs/kunit/%s/run\n", + suite->name); + return 0; +} + +/* + * The debugfs "run" file (/sys/kernel/debug/kunit//run) + * contains no information. Write to the file to trigger the test suite + * to run. + */ +static int debugfs_run_open(struct inode *inode, struct file *file) +{ + struct kunit_suite *suite; + + suite = (struct kunit_suite *)inode->i_private; + + return single_open(file, debugfs_print_run, suite); +} + +/* + * Trigger a test suite to run by writing to the suite's "run" debugfs + * file found at: /sys/kernel/debug/kunit//run + * + * Note: what is written to this file will not be saved. + */ +static ssize_t debugfs_run(struct file *file, + const char __user *buf, size_t count, loff_t *ppos) +{ + struct inode *f_inode = file->f_inode; + struct kunit_suite *suite = (struct kunit_suite *) f_inode->i_private; + + __kunit_test_suites_init(&suite, 1, true); + + return count; +} + +static const struct file_operations debugfs_results_fops = { + .open = debugfs_results_open, + .read = seq_read, + .llseek = seq_lseek, + .release = debugfs_release, +}; + +static const struct file_operations debugfs_run_fops = { + .open = debugfs_run_open, + .read = seq_read, + .write = debugfs_run, + .llseek = seq_lseek, + .release = debugfs_release, +}; + +void kunit_debugfs_create_suite(struct kunit_suite *suite) +{ + struct kunit_case *test_case; + struct string_stream *stream; + + /* If suite log already allocated, do not create new debugfs files. */ + if (suite->log) + return; + + /* + * Allocate logs before creating debugfs representation. + * The suite->log and test_case->log pointer are expected to be NULL + * if there isn't a log, so only set it if the log stream was created + * successfully. + */ + stream = alloc_string_stream(GFP_KERNEL); + if (IS_ERR(stream)) + return; + + string_stream_set_append_newlines(stream, true); + suite->log = stream; + + kunit_suite_for_each_test_case(suite, test_case) { + stream = alloc_string_stream(GFP_KERNEL); + if (IS_ERR(stream)) + goto err; + + string_stream_set_append_newlines(stream, true); + test_case->log = stream; + } + + suite->debugfs = debugfs_create_dir(suite->name, debugfs_rootdir); + + debugfs_create_file(KUNIT_DEBUGFS_RESULTS, S_IFREG | 0444, + suite->debugfs, + suite, &debugfs_results_fops); + + /* Do not create file to re-run test if test runs on init */ + if (!suite->is_init) { + debugfs_create_file(KUNIT_DEBUGFS_RUN, S_IFREG | 0644, + suite->debugfs, + suite, &debugfs_run_fops); + } + return; + +err: + string_stream_destroy(suite->log); + suite->log = NULL; + kunit_suite_for_each_test_case(suite, test_case) { + string_stream_destroy(test_case->log); + test_case->log = NULL; + } +} + +void kunit_debugfs_destroy_suite(struct kunit_suite *suite) +{ + struct kunit_case *test_case; + + debugfs_remove_recursive(suite->debugfs); + string_stream_destroy(suite->log); + kunit_suite_for_each_test_case(suite, test_case) + string_stream_destroy(test_case->log); +} -- cgit v1.3.1