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charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260910-gmem-inplace-conversion-v13-35-dd6fbf94f4e1@google.com> References: <20260910-gmem-inplace-conversion-v13-0-dd6fbf94f4e1@google.com> In-Reply-To: <20260910-gmem-inplace-conversion-v13-0-dd6fbf94f4e1@google.com> 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, 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=1789084533; l=5043; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=NatKLPwBc3zN+sgwD1yptGfPaJSyXn3xro4ZzLKzXNA=; b=+HCfmDQYtRRHU+KdI1880J9NXIgKQIU35pCgLEzsuOdShxo3wup3kgWBYmuKzRe2bbUSJDlt7 VE7BNNX2WzmBuFaBraSzGYiBEe4PzR5wWsQPNnPzsRwucpJGngF8CUq 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-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 5D01E40003 X-Stat-Signature: 8ymdhhm3bpotgjahiiqtixktrnyiuzq1 X-Rspam-User: X-HE-Tag: 1789084552-664008 X-HE-Meta: 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 ZqTnLGN6 MD1V8cmyfMrYQUHpx39H1lx0Xq/SbTyTmm851c4S7iZeafWpW4fOHPnE5ULXokCEkbYDU/SajJ/9caoEvL0ukyqSo354ekHNCHgl94n0lzKwuJPPLvMGvlvYAURB9bHfQvQg3L1hlihrcvubNKXewILTDl5lN+Uaa+rdD2ZpebsHMFWSVOvYuKO6YuWEHAz1goejxMRBkHqNDoZgrh6uCYiLOYXHj1HLWhQ5ChoQz4zaLgbIAfid1qRWZ3QlFQMHpeBSTa3ShRKEmw+G93n2zkZq4rf6RCG59W26Qm801qATNsLNt+PoxGy0l0zWyIwi8fSGcX9mo3Bt5kPgQUdMuQBEj3qKzt+Maqt5IcpFUHp2Wj3M1oCHBvMhmHHTaf8I9Z1PVzCDN/syWOm1KC02rPdYcxiFE+Er6Wfmq1DDdDmQFtCxoQvEgEgsI8vR0mLZB2LSgBVNyyTpibLIDT6ZvYz9XAAW01oV+3RwT 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. Co-developed-by: Ackerley Tng Signed-off-by: Ackerley Tng Signed-off-by: Sean Christopherson Tested-by: Shivank Garg Reviewed-by: Fuad Tabba --- .../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)); -- 2.55.0.1007.g17ff1f9808-goog