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Peter Anvin" , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Jonathan Corbet , Shuah Khan , Shuah Khan , Vishal Annapurve , Andrew Morton , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Youngjun Park , Qi Zheng , Shakeel Butt , Kiryl Shutsemau , Baoquan He , Jason Gunthorpe , John Hubbard , Peter Xu , tarunsahu@google.com, Randy Dunlap , Lorenzo Stoakes , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jason Gunthorpe , Fuad Tabba , Vlastimil Babka , Baoquan He Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-coco@lists.linux.dev, Ackerley Tng X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1788135916; l=5042; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=eSll1fxb3h9LF8Yf3q9CpNkCTF4Ydzl3TlGQL7Ph+7s=; b=a39svXm+jG0d08eS29xYIfcHadhb0Rsn115zbUmWat1bqwzQXYbDtRwIpu+8p+IQlZLDehNZp 958MlnX5Tw/A6TcC3FJLKB5t6/4/NYhZHNn1Bzru3gDtGYVNFpwCtfs X-Developer-Key: i=ackerleytng@google.com; a=ed25519; pk=sAZDYXdm6Iz8FHitpHeFlCMXwabodTm7p8/3/8xUxuU= X-Endpoint-Received: by B4 Relay for ackerleytng@google.com/20260225 with auth_id=649 X-Original-From: Ackerley Tng Reply-To: ackerleytng@google.com X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 1EABBA0009 X-Stat-Signature: rycg3bd1ggnd19we9wh7ithy7mapyyej X-HE-Tag: 1788135940-229300 X-HE-Meta: U2FsdGVkX1+0+7HjodLutPqjI+AbSfrWv198M4zN0S18DcfsoEe6awEzf4pb0UwM1KZkIc7Z4stddWU5lqb5MWLenUlIrG83+AoGxu+OVJx4H5bYrbaJdTXhGMjFDfrJSrKgMGg/nd5DUYMWT+DOf0sxJZQgx7TQhCa0v6a8rij4dts7yR1xojGHyw5F3k0r5lg6jv8WC+vNhhT4khdK9DG5fRYm0pzhO1fdoyHreEBONHzuHiF5qbFOLw2t651uM+VClor2yNzRyMWdrAij1gXfVgz7er2RCJpBanDk35vLu0cru14XQoVamn0sEm4QiqU3SGYfvo2T9iBaGEPdTq/jTJvm6d+MEy8TMbxlBT0ujTlxrdQaLVuPtYv5uQyZ5mhwDZ23kJpynPAktam4ap9ncj46uUv294AMNP+m3hcbF7ynnKhJFjh40abiVy+qHQ6egHZ6NLU7O1sXT2Ys6xIOHMaBOgsNkI5i15+xRRE4YlY1ECAAmgt9W5NCt5HKi9UsP42D4yX5qICkgiViAtprw1jTp6yUkBu++HBcB4TJ3UYT6c2RkY25wZDsTdlczbOxQrvFM/9vOxUW3nTm7ZNF5zJMTdWgCkQ0eupNMkdSHZlA8wrkBbo6DkbW8m/B5sJqNDrzI61nEWza8mKjteyBLev6jH9IGHF890RkNtDM2eam4FjSEji0VuUXriQBLE3L8kkdmg+2ICuZMC1wqWdR6S/+ng7H3dxfDFEy8k5uAwkOFR95Bhji53HX8wgKEQOqFgwrHHqXgZGhbJQBYOMMYCLsAEfPjmT8kx6Em6GZfe+6lrWm/JBIOFUZXZN5TpeEs2SMS7KZrFcKbe+J6oY7Y7DcM8qqr6chgmANs6PNIRm8bSe+nXGe7dlogWfE8jRTCnQnPMbzRyJ8Ul8bS6u9b1bzXjPVliGG8MvgTLfKhXNvHQsa9OLJ7905TBgg/+5P9TQ/WdeUdZEhvqM BWx3sWBO gYeZ6FoaY0BC3jC+kBD1dfsl1Wf9RB8GUFa4lalCdJ63dC4nZm1EfVBTPgLRVs8KLWb+UalzIq4wa+85XjCd8m4YCuq3UnTNGhVtIqFZP2d6xlbkdOlTSAkjCBEDvFMubEm4ZsD1D5G9aV94NJ9rdRU69wcfYHU2/TDfowWz1q7fA2yWVcGftMxnirdJET/9ACk4tOuxoaZWusyD8RqyV8+KxSo2CRV6pfbUP91mp+AsiRaJ3rfl1+4ePj3x2FtuTE/xccYZx7nnO4lIHl9MWuEyjz/ty+zkExItnbrKB1ap8dxKgAq0DjUa6W/HID+8MCqLFwgkHqOheLO/+c1Y/q+DQSR7s272armA/fe9auk9fvrF9v5CvsicNE2ZmZOFWNbkHrf6scEuCAx/LSsyKgd5NiiYtJ92alJwIOk3zDtp2cYQiz9A+8vB/LpmazpsH26pSZasEgZM+FGjhVeoDXI3IjdSFKhHEjF8x Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Sean Christopherson Add a test to verify that a guest_memfd's shared/private status is consistent across processes, and that any shared pages previously mapped in any process are unmapped from all processes. The test forks a child process after creating the shared guest_memfd region so that the second process exists alongside the main process for the entire test. The processes then take turns to access memory to check that the shared/private status is consistent across processes. Signed-off-by: Sean Christopherson Reviewed-by: Fuad Tabba Tested-by: Shivank Garg Co-developed-by: Ackerley Tng Signed-off-by: Ackerley Tng --- .../kvm/x86/guest_memfd_conversions_test.c | 118 +++++++++++++++++++++ 1 file changed, 118 insertions(+) diff --git a/tools/testing/selftests/kvm/x86/guest_memfd_conversions_test.c b/tools/testing/selftests/kvm/x86/guest_memfd_conversions_test.c index b7a54d2a90928..a972a09c5c6e5 100644 --- a/tools/testing/selftests/kvm/x86/guest_memfd_conversions_test.c +++ b/tools/testing/selftests/kvm/x86/guest_memfd_conversions_test.c @@ -2,7 +2,9 @@ /* * Copyright (c) 2024, Google LLC. */ +#include #include +#include #include #include @@ -326,6 +328,122 @@ GMEM_CONVERSION_TEST_INIT_SHARED(truncate) test_private(t, 0, 0, 'A'); } +/* Test that shared/private memory protections work and are seen from any process. */ +GMEM_CONVERSION_TEST_INIT_SHARED(forked_accesses) +{ + enum test_state { + STATE_INIT, + STATE_CHECK_SHARED, + STATE_DONE_CHECKING_SHARED, + STATE_CHECK_PRIVATE, + STATE_DONE_CHECKING_PRIVATE, + }; + + struct sync_state { + pthread_mutex_t mutex; + pthread_cond_t cond; + enum test_state step; + } *sync; + + pthread_mutexattr_t mattr; + pthread_condattr_t cattr; + pid_t child_pid, parent_pid; + int status; + + sync = kvm_mmap(sizeof(*sync), PROT_READ | PROT_WRITE, + MAP_SHARED | MAP_ANONYMOUS, -1); + + pthread_mutexattr_init(&mattr); + pthread_mutexattr_setpshared(&mattr, PTHREAD_PROCESS_SHARED); + pthread_mutex_init(&sync->mutex, &mattr); + pthread_mutexattr_destroy(&mattr); + + pthread_condattr_init(&cattr); + pthread_condattr_setpshared(&cattr, PTHREAD_PROCESS_SHARED); + pthread_cond_init(&sync->cond, &cattr); + pthread_condattr_destroy(&cattr); + + sync->step = STATE_INIT; + +#define TEST_STATE_AWAIT(__state) \ + do { \ + pthread_mutex_lock(&sync->mutex); \ + while (sync->step != (__state)) { \ + struct timespec ts, stop; \ + int ret; \ + \ + clock_gettime(CLOCK_REALTIME, &ts); \ + stop = timespec_add_ns(ts, 100 * 1000000UL); \ + \ + ret = pthread_cond_timedwait(&sync->cond, &sync->mutex, &stop); \ + if (ret == ETIMEDOUT) { \ + bool alive = (child_pid == 0) ? \ + (getppid() == parent_pid) : \ + (waitpid(child_pid, NULL, WNOHANG) == 0); \ + TEST_ASSERT(alive, "Other process exited prematurely"); \ + } else { \ + TEST_ASSERT(!ret, "pthread_cond_timedwait failed"); \ + } \ + } \ + pthread_mutex_unlock(&sync->mutex); \ + } while (0) + +#define TEST_STATE_SET(__state) \ + do { \ + pthread_mutex_lock(&sync->mutex); \ + sync->step = (__state); \ + pthread_cond_broadcast(&sync->cond); \ + pthread_mutex_unlock(&sync->mutex); \ + } while (0) + + parent_pid = getpid(); + child_pid = fork(); + TEST_ASSERT(child_pid != -1, "fork failed"); + + if (child_pid == 0) { + const char inconsequential = 0xdd; + + TEST_STATE_AWAIT(STATE_CHECK_SHARED); + + /* + * This maps the pages into the child process as well, and tests + * that the conversion process will unmap the guest_memfd memory + * from all processes. + */ + host_do_rmw(t->mem, 0, 0xB, 0xC); + + TEST_STATE_SET(STATE_DONE_CHECKING_SHARED); + TEST_STATE_AWAIT(STATE_CHECK_PRIVATE); + + TEST_EXPECT_SIGBUS(READ_ONCE(t->mem[0])); + TEST_EXPECT_SIGBUS(WRITE_ONCE(t->mem[0], inconsequential)); + + TEST_STATE_SET(STATE_DONE_CHECKING_PRIVATE); + exit(0); + } + + test_shared(t, 0, 0, 0xA, 0xB); + + TEST_STATE_SET(STATE_CHECK_SHARED); + TEST_STATE_AWAIT(STATE_DONE_CHECKING_SHARED); + + test_convert_to_private(t, 0, 0xC, 0xD); + + TEST_STATE_SET(STATE_CHECK_PRIVATE); + TEST_STATE_AWAIT(STATE_DONE_CHECKING_PRIVATE); + + TEST_ASSERT_EQ(waitpid(child_pid, &status, 0), child_pid); + TEST_ASSERT(WIFEXITED(status) && WEXITSTATUS(status) == 0, + "Child exited with unexpected status"); + + pthread_mutex_destroy(&sync->mutex); + pthread_cond_destroy(&sync->cond); + kvm_munmap(sync, sizeof(*sync)); + +#undef TEST_STATE_SET +#undef TEST_STATE_AWAIT +} + int main(int argc, char *argv[]) { TEST_REQUIRE(kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(KVM_X86_SW_PROTECTED_VM)); -- 2.55.0.897.gb25b4bd76c-goog