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 --- tools/testing/selftests/filelock/.gitignore | 1 + tools/testing/selftests/filelock/Makefile | 5 ++ tools/testing/selftests/filelock/ofdlocks.c | 120 ++++++++++++++++++++++++++++ 3 files changed, 126 insertions(+) create mode 100644 tools/testing/selftests/filelock/.gitignore create mode 100644 tools/testing/selftests/filelock/Makefile create mode 100644 tools/testing/selftests/filelock/ofdlocks.c (limited to 'tools/testing/selftests/filelock') diff --git a/tools/testing/selftests/filelock/.gitignore b/tools/testing/selftests/filelock/.gitignore new file mode 100644 index 000000000..825e899a1 --- /dev/null +++ b/tools/testing/selftests/filelock/.gitignore @@ -0,0 +1 @@ +ofdlocks diff --git a/tools/testing/selftests/filelock/Makefile b/tools/testing/selftests/filelock/Makefile new file mode 100644 index 000000000..478e82f8b --- /dev/null +++ b/tools/testing/selftests/filelock/Makefile @@ -0,0 +1,5 @@ +# SPDX-License-Identifier: GPL-2.0 + +TEST_GEN_PROGS := ofdlocks + +include ../lib.mk diff --git a/tools/testing/selftests/filelock/ofdlocks.c b/tools/testing/selftests/filelock/ofdlocks.c new file mode 100644 index 000000000..68bac28b2 --- /dev/null +++ b/tools/testing/selftests/filelock/ofdlocks.c @@ -0,0 +1,120 @@ +// SPDX-License-Identifier: GPL-2.0 + +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include "kselftest.h" + +static int lock_set(int fd, struct flock *fl) +{ + int ret; + + fl->l_pid = 0; // needed for OFD locks + fl->l_whence = SEEK_SET; + ret = fcntl(fd, F_OFD_SETLK, fl); + if (ret) + ksft_perror("fcntl()"); + return ret; +} + +static int lock_get(int fd, struct flock *fl) +{ + int ret; + + fl->l_pid = 0; // needed for OFD locks + fl->l_whence = SEEK_SET; + ret = fcntl(fd, F_OFD_GETLK, fl); + if (ret) + ksft_perror("fcntl()"); + return ret; +} + +int main(void) +{ + int rc; + struct flock fl, fl2; + int fd = open("/tmp/aa", O_RDWR | O_CREAT | O_EXCL, 0600); + int fd2 = open("/tmp/aa", O_RDONLY); + + ksft_print_header(); + ksft_set_plan(4); + + unlink("/tmp/aa"); + assert(fd != -1); + assert(fd2 != -1); + ksft_print_msg("opened fds %i %i\n", fd, fd2); + + /* Set some read lock */ + fl.l_type = F_RDLCK; + fl.l_start = 5; + fl.l_len = 3; + rc = lock_set(fd, &fl); + ksft_test_result(rc == 0, "set OFD read lock on first fd\n"); + if (rc != 0) + ksft_finished(); + + /* Make sure read locks do not conflict on different fds. */ + fl.l_type = F_RDLCK; + fl.l_start = 5; + fl.l_len = 1; + rc = lock_get(fd2, &fl); + if (rc != 0) + ksft_finished(); + if (fl.l_type != F_UNLCK) + ksft_exit_fail_msg("read locks conflicted\n"); + + /* Make sure read/write locks do conflict on different fds. */ + fl.l_type = F_WRLCK; + fl.l_start = 5; + fl.l_len = 1; + rc = lock_get(fd2, &fl); + if (rc != 0) + ksft_finished(); + ksft_test_result(fl.l_type != F_UNLCK, + "read and write locks conflicted\n"); + if (fl.l_type == F_UNLCK) + ksft_finished(); + + /* Get info about the lock on first fd. */ + fl.l_type = F_UNLCK; + fl.l_start = 5; + fl.l_len = 1; + rc = lock_get(fd, &fl); + if (rc != 0) + ksft_exit_fail_msg("F_OFD_GETLK with F_UNLCK not supported\n"); + ksft_test_result(fl.l_type != F_UNLCK, + "F_OFD_GETLK with F_UNLCK returned lock info\n"); + if (fl.l_type == F_UNLCK) + ksft_exit_fail(); + ksft_print_msg("F_UNLCK test returns: locked, type %i pid %i len %zi\n", + fl.l_type, fl.l_pid, fl.l_len); + + /* Try the same but by locking everything by len==0. */ + fl2.l_type = F_UNLCK; + fl2.l_start = 0; + fl2.l_len = 0; + rc = lock_get(fd, &fl2); + if (rc != 0) + ksft_exit_fail_msg + ("F_OFD_GETLK with F_UNLCK not supported\n"); + ksft_test_result(memcmp(&fl, &fl2, sizeof(fl)) == 0, + "F_UNLCK with len==0 returned the same\n"); + if (memcmp(&fl, &fl2, sizeof(fl))) { + ksft_exit_fail_msg + ("F_UNLCK test returns: locked, type %i pid %i len %zi\n", + fl.l_type, fl.l_pid, fl.l_len); + } + + /* Get info about the lock on second fd - no locks on it. */ + fl.l_type = F_UNLCK; + fl.l_start = 0; + fl.l_len = 0; + lock_get(fd2, &fl); + ksft_test_result(fl.l_type == F_UNLCK, + "F_OFD_GETLK with F_UNLCK return lock info from another fd\n"); + + ksft_finished(); +} -- cgit v1.3.1