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charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260507-gmem-inplace-conversion-v6-34-91ab5a8b19a4@google.com> References: <20260507-gmem-inplace-conversion-v6-0-91ab5a8b19a4@google.com> In-Reply-To: <20260507-gmem-inplace-conversion-v6-0-91ab5a8b19a4@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, ira.weiny@intel.com, 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, tabba@google.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 , Baoquan He , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Youngjun Park , Qi Zheng , Shakeel Butt , Kiryl Shutsemau , Jason Gunthorpe , 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 X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1778185365; l=3473; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=MrxYeYSTma0Mb5XDzsYrqnIjX6xeEwn3G6JnrRNoe3g=; b=0VEP4skWhIQasWMjxcAcMDpcs459UKxYi8KdDS9s3bb1dg3rVTnuVx6nr1Q387wZ6AyFWuVYZ xPqbT2t+67dAu32GIEYRnXHMoOH2qaV3dFEzK28LeXpEH9K3ovaObhs 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: rspam11 X-Rspamd-Queue-Id: 0A0F1100003 X-Stat-Signature: sm9bxqfiqmommx8c94rhn4rgnk7f5oby X-Rspam-User: X-HE-Tag: 1778185386-345632 X-HE-Meta: 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 03EB9WXh 72TPoU+L2VyIHjqLjh01pJceLSN6PScEW7mxUtoQz8K/k10w4YsnM+tc+1QAAYDIfKFNysb9bD3fkaTzQPfRR2oX3ssB+U9rGGmc1XPKrr8oafEVWnyvE+6dPCvG5W2Am4Nj3nNL9Ptkg2kMyc/8HGbG8R16mi/KR5uKfxB60G/dSxn/YYWn07e+0vWEOMwydS5iIIFzKaRrTh4SEDesJIlMDsf1Yo9JIDmrNI1sknT5FjObtf2IzBno/D2iUgsVM1nCgVSrOi0WlKiMgTd3OCCFgyNRcfUZP7MBFP7rbMwZqr2q5PAX5u8bFmaXcbqMyDOVD4hlgJ4XSI58WtLPttZUkCHtCk53ierscOjSN2D1M/nao0s8tose1K4xnGKQR/0FJLGBJDL0q6rJR2QHPfmD6mcuk5bW1aCFO4a4biKv2TF5hhJY+wMXAexX8LrlFBgJJPsr28Wt5ZBc= 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 Co-developed-by: Ackerley Tng Signed-off-by: Ackerley Tng --- .../kvm/x86/guest_memfd_conversions_test.c | 74 ++++++++++++++++++++++ 1 file changed, 74 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 960b2da8dd16d..4c33e21f04972 100644 --- a/tools/testing/selftests/kvm/x86/guest_memfd_conversions_test.c +++ b/tools/testing/selftests/kvm/x86/guest_memfd_conversions_test.c @@ -323,6 +323,80 @@ 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) +{ + /* + * No races are intended in this test, shared memory is only used to + * coordinate between processes. + */ + static enum { + STATE_INIT, + STATE_CHECK_SHARED, + STATE_DONE_CHECKING_SHARED, + STATE_CHECK_PRIVATE, + STATE_DONE_CHECKING_PRIVATE, + } *test_state; + pid_t child_pid; + + test_state = kvm_mmap(sizeof(*test_state), PROT_READ | PROT_WRITE, + MAP_SHARED | MAP_ANONYMOUS, -1); + +#define TEST_STATE_AWAIT(__state) \ + while (READ_ONCE(*test_state) != __state) { \ + if (child_pid != 0) { \ + int status; \ + pid_t pid; \ + do { \ + pid = waitpid(child_pid, &status, WNOHANG); \ + } while (pid == -1 && errno == EINTR); \ + if (pid == -1) \ + TEST_FAIL("Couldn't check child status."); \ + else if (pid != 0) \ + TEST_FAIL("Child exited prematurely."); \ + } \ + } + +#define TEST_STATE_SET(__state) WRITE_ONCE(*test_state, __state) + + 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); + + kvm_munmap(test_state, sizeof(*test_state)); +} + int main(int argc, char *argv[]) { TEST_REQUIRE(kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(KVM_X86_SW_PROTECTED_VM)); -- 2.54.0.563.g4f69b47b94-goog