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a=ed25519; pk=sAZDYXdm6Iz8FHitpHeFlCMXwabodTm7p8/3/8xUxuU= X-Developer-Signature: v=1; a=ed25519-sha256; t=1787735885; l=5042; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=mgO9cNUJjKY+AKFX9MzbbDfHmswDZG4pLv666WpGGk8=; b=4sXWR8XsmwnCwhSpArHLWN49pbbGfoT0AtcPlI36HRG/9GlMeMoVWb/i6RtUbq1xqd13MsZps yhnSFfxp2j3CfnwMrDrkdGOUO/3A2kREKcloGz8OlQCALrg5kqnLxLv X-Mailer: b4 0.16.0 Message-ID: <20260826-gmem-inplace-conversion-v11-36-0a15d8a799aa@google.com> Subject: [PATCH v11 36/46] KVM: selftests: Test that shared/private status is consistent across processes From: Ackerley Tng To: aik@amd.com, andrew.jones@linux.dev, binbin.wu@linux.intel.com, brauner@kernel.org, chao.p.peng@linux.intel.com, david@kernel.org, jmattson@google.com, jthoughton@google.com, michael.roth@amd.com, oupton@kernel.org, pankaj.gupta@amd.com, qperret@google.com, rick.p.edgecombe@intel.com, rientjes@google.com, shivankg@amd.com, steven.price@arm.com, willy@infradead.org, wyihan@google.com, yan.y.zhao@intel.com, forkloop@google.com, pratyush@kernel.org, suzuki.poulose@arm.com, aneesh.kumar@kernel.org, liam@infradead.org, Paolo Bonzini , Sean Christopherson , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. 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, Fuad Tabba , Vlastimil Babka 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 Content-Type: text/plain; charset="utf-8" X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: C652DC0004 X-Stat-Signature: t7fn1jxypu8rjereowtbt6cct73ze5rj X-HE-Tag: 1787735950-671692 X-HE-Meta: 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 /rhw/6YC 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 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)); -- 2.55.0.887.g758fc8c411-goog