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AJvYcCVQTJB23xTT2UA79n+R6/HorQviI5ITWDJ5wF1cPN/nhMJgNltIkmE4xlSK1Fn0mfjMMMGFEeEI0g==@kvack.org X-Gm-Message-State: AOJu0YxmqxpDEqB/dJjOpD1pNeezVkugxpAGSCs32QTeDqUqMVWzhyih kIwDDJncOqUDTtXO911uYFLYeurvVqHSgI9wO9YL/OaTGvKcwW7s/BTpuCx+28f3+V8cGECD4iP ufxPGPkquSLufmTLkmvDfdgCBrA== X-Google-Smtp-Source: AGHT+IHRvzzwMR4y0ztHkD4pksfFtRgb0k5+ziur45rOES6dge9lLW63A0tWR3m6aINjc/jUiO+gZmGPknwu1Q9I7g== X-Received: from pjpx13.prod.google.com ([2002:a17:90a:a38d:b0:33b:51fe:1a93]) (user=ackerleytng job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:1dc4:b0:33b:ade7:51d3 with SMTP id 98e67ed59e1d1-33bcf8f78c4mr6385553a91.20.1760731991624; Fri, 17 Oct 2025 13:13:11 -0700 (PDT) Date: Fri, 17 Oct 2025 13:12:07 -0700 In-Reply-To: Mime-Version: 1.0 References: X-Mailer: git-send-email 2.51.0.858.gf9c4a03a3a-goog Message-ID: Subject: [RFC PATCH v1 26/37] KVM: selftests: guest_memfd: Test that shared/private status is consistent across processes From: Ackerley Tng To: cgroups@vger.kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org Cc: ackerleytng@google.com, akpm@linux-foundation.org, binbin.wu@linux.intel.com, bp@alien8.de, brauner@kernel.org, chao.p.peng@intel.com, chenhuacai@kernel.org, corbet@lwn.net, dave.hansen@intel.com, dave.hansen@linux.intel.com, david@redhat.com, dmatlack@google.com, erdemaktas@google.com, fan.du@intel.com, fvdl@google.com, haibo1.xu@intel.com, hannes@cmpxchg.org, hch@infradead.org, hpa@zytor.com, hughd@google.com, ira.weiny@intel.com, isaku.yamahata@intel.com, jack@suse.cz, james.morse@arm.com, jarkko@kernel.org, jgg@ziepe.ca, jgowans@amazon.com, jhubbard@nvidia.com, jroedel@suse.de, jthoughton@google.com, jun.miao@intel.com, kai.huang@intel.com, keirf@google.com, kent.overstreet@linux.dev, liam.merwick@oracle.com, maciej.wieczor-retman@intel.com, mail@maciej.szmigiero.name, maobibo@loongson.cn, mathieu.desnoyers@efficios.com, maz@kernel.org, mhiramat@kernel.org, mhocko@kernel.org, mic@digikod.net, michael.roth@amd.com, mingo@redhat.com, mlevitsk@redhat.com, mpe@ellerman.id.au, muchun.song@linux.dev, nikunj@amd.com, nsaenz@amazon.es, oliver.upton@linux.dev, palmer@dabbelt.com, pankaj.gupta@amd.com, paul.walmsley@sifive.com, pbonzini@redhat.com, peterx@redhat.com, pgonda@google.com, prsampat@amd.com, pvorel@suse.cz, qperret@google.com, richard.weiyang@gmail.com, rick.p.edgecombe@intel.com, rientjes@google.com, rostedt@goodmis.org, roypat@amazon.co.uk, rppt@kernel.org, seanjc@google.com, shakeel.butt@linux.dev, shuah@kernel.org, steven.price@arm.com, steven.sistare@oracle.com, suzuki.poulose@arm.com, tabba@google.com, tglx@linutronix.de, thomas.lendacky@amd.com, vannapurve@google.com, vbabka@suse.cz, viro@zeniv.linux.org.uk, vkuznets@redhat.com, wei.w.wang@intel.com, will@kernel.org, willy@infradead.org, wyihan@google.com, xiaoyao.li@intel.com, yan.y.zhao@intel.com, yilun.xu@intel.com, yuzenghui@huawei.com, zhiquan1.li@intel.com Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: zfud7pyjjudxuuyku5eiowuxj6zozd94 X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: D2D86A000F X-HE-Tag: 1760731992-745295 X-HE-Meta: U2FsdGVkX184nn4BQgR9Q3rE02jPgmu6bFmFrglR3ZKAQAmUn5ycEqTC1/ZgVM+1eAnuNEMrgfpPaTlIEkq0hDS9pdnbsXLWww7sS6rjA2N3H1GHnzJjf81PfOhTbATWw5aAR2UAXOMm+wKTSURVc+gCEIA7BGTdwD5vsyWRe6kCjPnhb0HVszuN8rrFVnPdE2adfG+OQmFjbq5B3WuEaloJbV+tQnpk0ghMYK8KHmE+8swKwawe3x8I0KoAF84dTTJwCuLaMZd5cViqqjjXPJdoYEa7EhFADihi8Pr8k9iosMT8G2lLCkyltZdxbKfV7W6zXpKcm8wxzQkmSU/0chV4w74laimeTEr9oDHdM+cdsWZtK/rSYqWRpBJ2ENQx3y1p/KcmgsrcheR/TlbwRKzOaNKSb5tbmGEz2S7bHRbPnryMlRmef48N7iNeStoRIFxPD4hMvyKo0HhhKMdP+oATTkAlnWSlBp12N9L6qHEi8CWVGqMDttreVjkTDxZO3EOQr3ax+lO47URvIPQuft7HVrf+ZxRFuWVErY9EtaQUMWAwrgg+dTDaq7H8XhMcAe9pKIsMHKVMw8yfEWirLF4i53/faJ1W2zkF/e7T3gN1x0E39pcVMnycecJWiodaopVyGqmVK5CcrR6NLlaWxSX2FU2cVsL3xOoEDRv6KxqhcfNuIirCnAfXWIkiWTesYZmOzb/1gLJ/O4Xe5CcbmRY+DTQ1Vs+HaG/fibh5xn2C/T2PJfJZ8YpzPcdWZvec3JB0JPLrtWFWjHPfknx39XvO5PEFLXE3YSqn0sSD4S4Pzi+vwyu/YBPieeSUiTyKGZFZnn4XQJXHA7/OfVZzmZlJB2GdqbMqynGrfvX3ArcGkk7f7iBiL6yTvR6L6qR2np6ZZnMos9e07+5+Aj7EDfzoeq7/485OD5rEPzEzUgR/tsMbjj8ea1Zop4fow0O5xdPnvJiWwWQ25yhvuEZ MXdtwBLw 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 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. 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/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 907d415d72315..e6abf2d30c62d 100644 --- a/tools/testing/selftests/kvm/guest_memfd_conversions_test.c +++ b/tools/testing/selftests/kvm/guest_memfd_conversions_test.c @@ -330,6 +330,80 @@ 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)); -- 2.51.0.858.gf9c4a03a3a-goog