From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E8DF4C4332F for ; Thu, 17 Nov 2022 00:24:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234402AbiKQAYF (ORCPT ); Wed, 16 Nov 2022 19:24:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57236 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234346AbiKQAYB (ORCPT ); Wed, 16 Nov 2022 19:24:01 -0500 Received: from mail-pj1-x104a.google.com (mail-pj1-x104a.google.com [IPv6:2607:f8b0:4864:20::104a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4DA28627C1 for ; Wed, 16 Nov 2022 16:24:00 -0800 (PST) Received: by mail-pj1-x104a.google.com with SMTP id v10-20020a17090a7c0a00b00215deac75b4so226248pjf.3 for ; Wed, 16 Nov 2022 16:24:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=OQIty0gkGvimYsfAtcoPy8df73fwY+kl22+jSnaHr3Q=; b=XawF3gkr8CSKZ24fVYfQH/likVJmqrI6J+VgfY0e5oCqzv9OjobeFrDLWibgksGjp1 bpT/73ID8XYCUWtDkHG2HllTtEz582TclewSThnNE0l3c5yF0jvFHZ1/ZL/wudSFnfNc 22czahecA+4YL4y5BIk2STkzJ4Sl4F0uiU6ADlDXxHmn4GtTD2LizNnfounT0TGHV1ul /PifA+5TNyMgrcAklqK6NQw2i1wpsS5JW7doMrokg2FmWTpQJbyYBuHmTEcGBLiW9ITd 7j6WcKeXgdmwApf4zSyXL5jmPW52XoIa3JdjF+0UF72NtCpSP+95c3KKIAP0X74sDOd8 MIUQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=OQIty0gkGvimYsfAtcoPy8df73fwY+kl22+jSnaHr3Q=; b=6csuKWjYzXG6UOEy7wQWRLlXe+IpgqQ5h4Na+xm0hb1IDaE7j46y4dXeAh1O2imtng XvjxkkVmb5MD1G6Y2Skj4MUDY3nX0Di4rusUIwRviwxu5VSvicPuQTt+3mViYsg8PQ86 RdbQL/7N57X7gKRXKvNP742HhMfSYkLASttoOqRi41P/qEp4LG8yMePy/RDnNxpSgRqP 9/ezDVn/l2C0iwqa++ImyEqWs/kp7sewfqEmgJVQM5P1uN2v1cjO3cEJNbLY4mhcH28S Rx1bg1jx40+f8lT/spGr1vg645h1D7TfIy3cCwOUE7ViGkQ080xQnphLggo+YSa6+dbq 5cBA== X-Gm-Message-State: ANoB5pmEDwNkfTfWrYrfetMdZQwFCjGYeMCES/ubzyjkH/CiwDkZC+Ed M/Ej0t5VDcVVnNxb1Mnf22FC2sP16fY= X-Google-Smtp-Source: AA0mqf6UG7Saff0XvDUGklOofeYsmwntM1MGQ71SgLhPhHqsgDLhnxcroheVO1wVLxnzQCCJ1Ru+MrMvNxE= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:aa7:9628:0:b0:56d:c3af:2d7f with SMTP id r8-20020aa79628000000b0056dc3af2d7fmr464212pfg.64.1668644639816; Wed, 16 Nov 2022 16:23:59 -0800 (PST) Reply-To: Sean Christopherson Date: Thu, 17 Nov 2022 00:23:50 +0000 In-Reply-To: <20221117002350.2178351-1-seanjc@google.com> Mime-Version: 1.0 References: <20221117002350.2178351-1-seanjc@google.com> X-Mailer: git-send-email 2.38.1.431.g37b22c650d-goog Message-ID: <20221117002350.2178351-3-seanjc@google.com> Subject: [PATCH 2/2] KVM: arm64: selftests: Disable single-step without relying on ucall() From: Sean Christopherson To: Marc Zyngier Cc: James Morse , Alexandru Elisei , Suzuki K Poulose , Oliver Upton , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, Reiji Watanabe , Sean Christopherson Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Automatically disable single-step when the guest reaches the end of the verified section instead of using an explicit ucall() to ask userspace to disable single-step. An upcoming change to implement a pool-based scheme for ucall() will add an atomic operation (bit test and set) in the guest ucall code, and if the compiler generate "old school" atomics, e.g. 40e57c: c85f7c20 ldxr x0, [x1] 40e580: aa100011 orr x17, x0, x16 40e584: c80ffc31 stlxr w15, x17, [x1] 40e588: 35ffffaf cbnz w15, 40e57c <__aarch64_ldset8_sync+0x1c> the guest will hang as the local exclusive monitor is reset by eret, i.e. the stlxr will always fail due to the VM-Exit for the debug exception. Link: https://lore.kernel.org/all/20221006003409.649993-8-seanjc@google.com Cc: Oliver Upton Cc: Marc Zyngier Signed-off-by: Sean Christopherson --- .../selftests/kvm/aarch64/debug-exceptions.c | 28 ++++++++++--------- 1 file changed, 15 insertions(+), 13 deletions(-) diff --git a/tools/testing/selftests/kvm/aarch64/debug-exceptions.c b/tools/testing/selftests/kvm/aarch64/debug-exceptions.c index 91f55b45dfc7..65cd7e4f07fa 100644 --- a/tools/testing/selftests/kvm/aarch64/debug-exceptions.c +++ b/tools/testing/selftests/kvm/aarch64/debug-exceptions.c @@ -241,7 +241,6 @@ static void guest_svc_handler(struct ex_regs *regs) enum single_step_op { SINGLE_STEP_ENABLE = 0, - SINGLE_STEP_DISABLE = 1, }; static void guest_code_ss(int test_cnt) @@ -258,7 +257,7 @@ static void guest_code_ss(int test_cnt) GUEST_SYNC(SINGLE_STEP_ENABLE); /* - * The userspace will veriry that the pc is as expected during + * The userspace will verify that the pc is as expected during * single step execution between iter_ss_begin and iter_ss_end. */ asm volatile("iter_ss_begin:nop\n"); @@ -268,11 +267,9 @@ static void guest_code_ss(int test_cnt) bvr = read_sysreg(dbgbvr0_el1); wvr = read_sysreg(dbgwvr0_el1); + /* Userspace disables Single Step when the end is nigh. */ asm volatile("iter_ss_end:\n"); - /* Disable Single Step execution */ - GUEST_SYNC(SINGLE_STEP_DISABLE); - GUEST_ASSERT(bvr == w_bvr); GUEST_ASSERT(wvr == w_wvr); } @@ -364,15 +361,12 @@ void test_single_step_from_userspace(int test_cnt) TEST_ASSERT(cmd == UCALL_SYNC, "Unexpected ucall cmd 0x%lx", cmd); - if (uc.args[1] == SINGLE_STEP_ENABLE) { - debug.control = KVM_GUESTDBG_ENABLE | - KVM_GUESTDBG_SINGLESTEP; - ss_enable = true; - } else { - debug.control = KVM_GUESTDBG_ENABLE; - ss_enable = false; - } + TEST_ASSERT(uc.args[1] == SINGLE_STEP_ENABLE, + "Unexpected ucall action 0x%lx", uc.args[1]); + debug.control = KVM_GUESTDBG_ENABLE | + KVM_GUESTDBG_SINGLESTEP; + ss_enable = true; vcpu_guest_debug_set(vcpu, &debug); continue; } @@ -385,6 +379,14 @@ void test_single_step_from_userspace(int test_cnt) "Unexpected pc 0x%lx (expected 0x%lx)", pc, test_pc); + if ((pc + 4) == (uint64_t)&iter_ss_end) { + test_pc = 0; + debug.control = KVM_GUESTDBG_ENABLE; + ss_enable = false; + vcpu_guest_debug_set(vcpu, &debug); + continue; + } + /* * If the current pc is between iter_ss_bgin and * iter_ss_end, the pc for the next KVM_EXIT_DEBUG should -- 2.38.1.431.g37b22c650d-goog