From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 68E15396591; Mon, 18 May 2026 20:25:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779135926; cv=none; b=i4Qgpbe/ZWA67N2XLmNyuMcuWgROp5DNdUYfUvhd6+oj/GMnzB5M3PgxVM6nQCTjSOWGjuwoMMNPTtLZlqIBUpqQdrswSodo7SK4q3d9yNjAr8oCQhQhgHo7MzBJxVTn/CI75bq+bzW/tVqjBwWOwBX8itI+wrcKotS4PKlpSeg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779135926; c=relaxed/simple; bh=mAo+nNH9B73epRdJSYz4wQGFb0T3sYNTm3+FkEL+Dl8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=P1hlfJq0e0qgEHjkbDlXT8JnqH4Hepr3kFyPew66zhCJM6xU/cCYCO8mdz6Gwc0p1+2d7VJVBwAAxPtj0DWZuznm/OYN3gJfMS6tLDRoed05BiUXNWTKckvC7JRv1dujqkYjYtb6esjKHBpsXEN9N6Ps+1EhwlG8HVca/+sAuIU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GLLyCX9H; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="GLLyCX9H" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1163EC2BCC6; Mon, 18 May 2026 20:25:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1779135926; bh=mAo+nNH9B73epRdJSYz4wQGFb0T3sYNTm3+FkEL+Dl8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GLLyCX9H4Kr4vbiBMGoOMN6XW1G7e6nsrqa89blRaChUBFByh/bleDRfMF6FmJy6o EJfFK9s1yNkRWs2Gw8xIKOPTSDtPDrzVxY4g1m48BQ4wVMJrbGwlXkv39Fpe4e0iUT jxmb0eJYBomlPi5jXUxnC0OJ1L8SJTopzTNqDFyvxACUthrxK7UmlQDS6B1E0Bk6BX IBEDw1yLXQZL9+jz6NvAGWH6IYqRub9FwgvrnG3KOryOVQumH3+rhjtjowUBS1at+O tH3Yv1GhMq//khljfbvdGVGcp52YW7OPdVopiQ9xbWor56sPCCAbr8061I9M3FqbWA rjQOLAJRFkhKw== From: Yosry Ahmed To: Sean Christopherson Cc: Paolo Bonzini , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Yosry Ahmed , Yosry Ahmed Subject: [PATCH 6/8] KVM: selftests: Trigger save+restore randomly in the #PF stress test Date: Mon, 18 May 2026 20:25:12 +0000 Message-ID: <20260518202514.2037078-7-yosry@kernel.org> X-Mailer: git-send-email 2.54.0.563.g4f69b47b94-goog In-Reply-To: <20260518202514.2037078-1-yosry@kernel.org> References: <20260518202514.2037078-1-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 From: Yosry Ahmed 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. Signed-off-by: Yosry Ahmed --- .../kvm/x86/stress_save_restore_pf_test.c | 56 ++++++++++++++++--- 1 file changed, 48 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 12da74b4f725c..60a013e0f14fb 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" @@ -99,14 +101,40 @@ 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_accesses); + 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; + pthread_t sigusr_thread; struct kvm_vcpu *vcpu; int r, i, count = 0; struct kvm_vm *vm; @@ -140,18 +168,28 @@ int main(int argc, char *argv[]) /* Map the page tables so that the guest #PF handler can walk them */ virt_map_page_tables(vm); + /* Initialize the thread sending SIGUSR and install the handler */ + pthread_create(&sigusr_thread, NULL, sigusr_thread_fn, + (void *)pthread_self()); + 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 exists 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); @@ -166,6 +204,8 @@ int main(int argc, char *argv[]) sync_global_from_guest(vm, guest_accesses); pr_info("Guest page accesses: %lu\n", guest_accesses); + pthread_cancel(sigusr_thread); + pthread_join(sigusr_thread, NULL); kvm_vm_free(vm); return 0; } -- 2.54.0.563.g4f69b47b94-goog