From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 276B337E31F for ; Fri, 13 Mar 2026 06:13:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773382419; cv=none; b=YfOhcHaRw7YXB2TFPxZ34C1z+3WuinqwL5nyxrIOJms8wpVuSwaRZ0T97DsV7VxfZSNrCvK9+Uvy+b+ujjW5FQYc6izuI+NQ+8iM8j4TMyAxb1doQQCBEOaBcyrG+8X/saYFsIXR9KGLnH8JZCc0TW50/42FviVcodEoeK9omck= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773382419; c=relaxed/simple; bh=AsQimpP6VPCpX/GeA3PXLmrBwdE8bqvci7sU/Y3ufXs=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=oMbkvG87/XyEtyqKcgP6ENQWDTihxsp/D0vPsM8FbwUbSGF/INQjLA/xVXGqNVzfxN7m6Vm7NZj+0J36hyj/o8Hw2C8z6ssZBPO7XXy0bz3JgWxg3pqEys/6kD70j0o2WrfEHixzL3dTwzYtrEtf9N/1Rrz5VMbE0yaG1si/yTE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--ackerleytng.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=XRiWkCSV; arc=none smtp.client-ip=209.85.216.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--ackerleytng.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="XRiWkCSV" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-35845fcf0f5so2150323a91.0 for ; Thu, 12 Mar 2026 23:13:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1773382413; x=1773987213; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=CYNGOoNNh7RW693z87teeFuj/YH+4YrK5JAx0qc/QTU=; b=XRiWkCSVLhdFTGBcZYNn1hBrtn1DzZoJTtIiFrcoI634tKr2aV3v8A4OVoQDD3emxa DVO6tQAcQLKCFK+utKfawyvYsc6tN4LeritZAudo5dkjmj9EmPQakvpOQPpYdKyMY0as WafnpAarM72O03lRdBRLkT1XlbQkqZUnb4nAsuYfc9PtmCXhAjpTHgj0b5omOtwPWCyq +osjql4VBcXQZQ0s1d+x/6hcGXqwubE1ZJAGSJXTSV34OFY0btK5gZmWs7aZzI87/WOQ RMMLkHkcbISiqxBPeeGDz1AhSfjD18+VOHKHLZJiUHC7n+dl7+9g8m4I+MhpZeMVbGMZ p1lg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1773382413; x=1773987213; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=CYNGOoNNh7RW693z87teeFuj/YH+4YrK5JAx0qc/QTU=; b=hHfv7ipCv9cEbogbGrOIvuiTrFUUw05N1CRfvOypgNvxZMgoMyT3tY3a4x6rryosmI d6ffegIkydWbmus1VZo5AGIEglnstovmYR5ep4sqN+NjM1Fb6TyDNdGP4cbH3IoG9+Jy pSmqPK6WAF1Y6N7++pZ2tPv9LUesiDfTmqbqp9E8OZpfUpQLY1O6Dy9i40z+vPnUZC6T 00E7yxKUP9Qb8S2WUUujCUTmhXa7L0AinQASwT8PUjfz7SVcy//HttGdDct/mDFU3tk0 wuicT43ui9GbbcJsl5poTv4IQTm0PYs5CU3BP4l4KMEp6/rsVEIGGwKevg5FGrxyYE5O XTyw== X-Forwarded-Encrypted: i=1; AJvYcCU7gPb1Elk3KHfU9kKJHw36JG/SFoDdfRHmg4mnZFjQ6kaAgB5JBlV7sy9YQYBdJWGFs9e5tdaeUOr7JTUZ7Gk=@vger.kernel.org X-Gm-Message-State: AOJu0YyjF2C9KeeVzGoZsVyFQzShOipsVyNMm9PlXStlW03tW0uZoPNN FdOP+CMJT8M1w7qd+NHDw1dU8Y9bohwKqupF3AcI1XMdU/J7ZD4alixzf8DCrbhgyjsxbyT2ICi qno7nk3z03dwZU1dIDouuM8s77g== X-Received: from pjvf3.prod.google.com ([2002:a17:90a:da83:b0:359:86b9:176d]) (user=ackerleytng job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:1fcc:b0:359:8dfc:d39a with SMTP id 98e67ed59e1d1-35a11940b38mr5012681a91.4.1773382412954; Thu, 12 Mar 2026 23:13:32 -0700 (PDT) Date: Fri, 13 Mar 2026 06:13:06 +0000 In-Reply-To: <20260313-gmem-inplace-conversion-v3-0-5fc12a70ec89@google.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260313-gmem-inplace-conversion-v3-0-5fc12a70ec89@google.com> X-Developer-Key: i=ackerleytng@google.com; a=ed25519; pk=sAZDYXdm6Iz8FHitpHeFlCMXwabodTm7p8/3/8xUxuU= X-Developer-Signature: v=1; a=ed25519-sha256; t=1773382364; l=3457; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=VmcKXTBk9OIQ151891CwT/J/1loQnzBkF6yygKgeTPk=; b=z3KgLYQjwUaYikW8XAOodIwQ93xrZsUpHVKoezptz6hG2AKa7cWLyyzelsKs++CcZexA/5KQ8 RM4G7PiCRZXBpyLNHyr7/eGs7fAM0F2Z7u3swsCGBSOSQZvOCOykYJ5 X-Mailer: b4 0.14.3 Message-ID: <20260313-gmem-inplace-conversion-v3-27-5fc12a70ec89@google.com> Subject: [PATCH RFC v3 27/43] 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, ira.weiny@intel.com, jmattson@google.com, jroedel@suse.de, 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 , 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, Ackerley Tng Content-Type: text/plain; charset="utf-8" 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 --- .../selftests/kvm/guest_memfd_conversions_test.c | 74 ++++++++++++++++++++++ 1 file changed, 74 insertions(+) diff --git a/tools/testing/selftests/kvm/guest_memfd_conversions_test.c b/tools/testing/selftests/kvm/guest_memfd_conversions_test.c index 89881a71902e6..c1a9cc7c9fae6 100644 --- a/tools/testing/selftests/kvm/guest_memfd_conversions_test.c +++ b/tools/testing/selftests/kvm/guest_memfd_conversions_test.c @@ -322,6 +322,80 @@ 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)); -- 2.53.0.851.ga537e3e6e9-goog