From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D6CEB4CA272; Thu, 4 Jun 2026 20:36:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780605365; cv=none; b=kHtCoNB4xY0z8Sd7enCJ8wTc/TgQC+HTwTg+v3042Il8XHCpiChZO/fm7L6cpPtGqWLyKZF0FS66qKaidMG8XZybv5hriYj5Kq9eEkyj9bZ3zXTUOSPTNrLW9DLp9Slgs5Vrx9EH/CCh7Vd+VIRoin0YusxePQhKkY1y9aYpbKM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780605365; c=relaxed/simple; bh=8iBKASzbz9mlsV2tDL6ihk64B3BCpKYDiU7NsrNIa1k=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Mg3YtgPC8IpT+dI0ni+Bb2OgQbOR1Uog8IAGk2whpV1dKEBnefV8s/fg1HMSXBWTrY1OnifSQV1z8v+wCyS/fmb1pxINvwbSmIgQDo2iLG3rSk7OgzuSfK/BfAEUtaiA/M3ZXGSXcO9w9hCfdJ14mJXgSYM077CuvoO5hCcqtic= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DsdXjiG9; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DsdXjiG9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 90AEB1F0089B; Thu, 4 Jun 2026 20:36:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780605362; bh=VsVTfc8q8V6S6PMSRT8ydmbG/vrsrRUOqsArdYthojc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=DsdXjiG9GbOPWYH/5Mn5OIaekbHvRlV0WFKW+s3vVwJ32A5vPgBWAUkin1ek+tTLI cY/9K/DwQgwHIXqIQL2I5e0AqXNQollFgKkNgQiCknboibnKUDv4QQMXiuXkvB5Eq7 hKmHkasH8baEZ1YzqpJdbFGr9xgkb3M6vshsFrV8b2CXWAXJ8/Nfsx+s5TiARoW7OX dLio1Bsz6M5ZeXSlgUQ6v4sMeoFeAY9z15J9Vt8KDo4wAl9qS1WvpCHyLLmD11hB6L 7rjmjnJTlLu+Ea0skafFuK+/B+e/BGJEMAFnH1zV9IHx9ayVPqoaYnhFORz313CO6h CDSxDQDq+ryAA== From: Yosry Ahmed To: Sean Christopherson Cc: Paolo Bonzini , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Yosry Ahmed Subject: [PATCH v2 08/10] KVM: selftests: Trigger save+restore randomly in the #PF stress test Date: Thu, 4 Jun 2026 20:35:44 +0000 Message-ID: <20260604203546.365658-9-yosry@kernel.org> X-Mailer: git-send-email 2.54.0.1032.g2f8565e1d1-goog In-Reply-To: <20260604203546.365658-1-yosry@kernel.org> References: <20260604203546.365658-1-yosry@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Instead of an explicit GUEST_SYNC() after each access+#PF, run another thread that keeps sending SIGUSR to the vCPU thread, essentially triggering exits to userspace and save+restore on random points in guest execution. This makes the test a lot more meaningful as it opens the door to exercising race conditions between #PF handling in the guest and save+restore in the host. The signals are ignored using SIG_IGN outside of __vcpu_run() to avoid interrupting other ioctls/sysctls performed by the test. Assisted-by: Gemini:gemini-3.1-pro Signed-off-by: Yosry Ahmed --- .../kvm/x86/stress_save_restore_pf_test.c | 59 ++++++++++++++++--- 1 file changed, 51 insertions(+), 8 deletions(-) diff --git a/tools/testing/selftests/kvm/x86/stress_save_restore_pf_test.c b/tools/testing/selftests/kvm/x86/stress_save_restore_pf_test.c index 622d102179e66..92efb7ac9d95f 100644 --- a/tools/testing/selftests/kvm/x86/stress_save_restore_pf_test.c +++ b/tools/testing/selftests/kvm/x86/stress_save_restore_pf_test.c @@ -5,6 +5,8 @@ #include #include #include +#include +#include #include #include "test_util.h" @@ -94,15 +96,41 @@ static void guest_access_memory(void *arg) /* Clear the present bit again so it faults next time */ *guest_get_pte(vaddr) &= ~pte_present_mask; invlpg(vaddr); + } +} + +static void *sigusr_thread_fn(void *arg) +{ + pthread_t vcpu_thread = (pthread_t)arg; - GUEST_SYNC(guest_faults); + for (;;) { + pthread_testcancel(); + pthread_kill(vcpu_thread, SIGUSR1); + usleep(100); } + return NULL; +} + +static void dummy_signal_handler(int signo) {} +static struct sigaction sa; + +static void vcpu_sigusr_listen(void) +{ + sa.sa_handler = dummy_signal_handler; + sigaction(SIGUSR1, &sa, NULL); +} + +static void vcpu_sigusr_ignore(void) +{ + sa.sa_handler = SIG_IGN; + sigaction(SIGUSR1, &sa, NULL); } int main(int argc, char *argv[]) { struct kvm_x86_state *state; int r, i, level, count = 0; + pthread_t sigusr_thread; gpa_t gpa, pgtable_gpa; struct kvm_vcpu *vcpu; struct kvm_vm *vm; @@ -151,18 +179,30 @@ int main(int argc, char *argv[]) pgtable_gpa = PTE_GET_PA(pte); } + /* Initialize the thread sending SIGUSR and install the handler */ + vcpu_sigusr_ignore(); + r = pthread_create(&sigusr_thread, NULL, sigusr_thread_fn, + (void *)pthread_self()); + TEST_ASSERT(!r, "pthread_create() failed: %d", r); + while (count++ < NR_ITERATIONS) { + /* + * Only handle SIGUSR while the vCPU is running, otherwise + * ignore it to avoid interrupting other ioctls/syscalls. + */ + vcpu_sigusr_listen(); r = __vcpu_run(vcpu); - TEST_ASSERT(!r, "vcpu_run failed"); - TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO); - - get_ucall(vcpu, &uc); - if (uc.cmd == UCALL_ABORT) { + if (r == -1) + TEST_ASSERT_EQ(errno, EINTR); + vcpu_sigusr_ignore(); + + /* The guest only exits due to a signal or failed assertion */ + if (!r) { + TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO); + TEST_ASSERT_EQ(get_ucall(vcpu, &uc), UCALL_ABORT); REPORT_GUEST_ASSERT(uc); break; } - TEST_ASSERT_EQ(uc.cmd, UCALL_SYNC); - TEST_ASSERT_EQ(uc.args[1], count - 1); state = vcpu_save_state(vcpu); @@ -175,8 +215,11 @@ int main(int argc, char *argv[]) } sync_global_from_guest(vm, guest_faults); + TEST_ASSERT(guest_faults > 0, "No guest page faults triggered"); pr_info("Guest page faults: %lu\n", guest_faults); + pthread_cancel(sigusr_thread); + pthread_join(sigusr_thread, NULL); kvm_vm_free(vm); return 0; } -- 2.54.0.1032.g2f8565e1d1-goog