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charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260428-gmem-inplace-conversion-v5-40-d8608ccfca22@google.com> References: <20260428-gmem-inplace-conversion-v5-0-d8608ccfca22@google.com> In-Reply-To: <20260428-gmem-inplace-conversion-v5-0-d8608ccfca22@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, 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=1777418714; l=3473; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=za9mbinhXQlrBGNX8T7yWO9RNCSzSfL649W98OVJnA0=; b=lkg9YFQlIbB1hlTVjPrGIukY3fzR7s6d2zyamzlqVzgGFcxL3JfBdyNqZw0C9MA3wGvekD5Qw vGC5eHP/UQ6DLO56Vn4ZHsd+yy/F3u/Qr3S2vgUpUxAbrEbmXmlAi+g 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-Stat-Signature: 5ybkrc6phciubpyxdmk8zm38m13j1ibt X-Rspamd-Queue-Id: B7B2240004 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1777418738-264392 X-HE-Meta: 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 gZihziEZ tAC0WpEKqhqfgU9GhtqBpRcN7u9oNmLYnb7AIFyTlT31wM4uKcrjPUr/jzRJZXA3PCC91zF4Q7QpyoUoMbJAAUfiq6eWckGoRmLHJtZH7CFj+sUdvlQDEZN9FIifcF7wrp5cEbWGmkCtyFHpEdQ6yjLXhbb0sHOfPzYAyj91DWpeafnZ/cZj89bdLEwMSdTmzO9gy/e0Pribm/55frMXslNsC6toStyx6vgB1ELABRGG96JsbWptvE1Cd8nTrTeh4PCpR8S9aKk8uhHH0LQFYgWbD+mZN+6WjUVHIpdL0DJqJGNtLg8tjnrZoqEye2ZP/N3aVXCev2yLIRkxwzvfYZbI6J3AMBDPA2B6YGdPG88fSjrcK79XnNJhXqnS/5O2AllpNE/DY8lmFDnpe+Mb5mX/GpLxtjDW7vtBm8VK2B3/l+BrEc6zKqoM4EQ/4DT6ekgFUYaa58gCJuOo= 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 8dfbf3630cec2..21918b83d3792 100644 --- a/tools/testing/selftests/kvm/x86/guest_memfd_conversions_test.c +++ b/tools/testing/selftests/kvm/x86/guest_memfd_conversions_test.c @@ -334,6 +334,80 @@ 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)); -- 2.54.0.545.g6539524ca2-goog