From patchwork Fri Dec 9 01:53:06 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oliver Upton X-Patchwork-Id: 13069146 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D97B8C001B2 for ; Fri, 9 Dec 2022 01:56:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=M/BdFes/touqFev8lvS97gcVq9L1n5M0Pgu4zK8lS9M=; b=IpmuTdn5SPAruW 7ls/ANxXVHt+dcLv4Q5OTsr3OqCmYgB+LjBF2IY3UjIT0b32Ijz3AFgMOspyuOscEixbk4L5kgkKz 05wniqCrvDfiMXYKCVfd11iyAP8LBTIBg/TVMiFQ9bg7HPzdzMppi1LtV90pAJsVUCJ4B1UENCUfZ f8K/6rUb3TtjTq0c6PWrzNFyWtXZusRwledo2xodCBQgDLq4B1ejP5sUD7KfIuJHx9xVjjwRQXBKb 2nHk/fZ6lPX1002SNqEUBfLtazXN5pWGTYqJJB8CT4Yo8chi9oSGjYdI6+rk+r1fkyd38UDRozkxN 2auTTDQ6vvcGYplREeTg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1p3Sbh-000W9Y-Vs; Fri, 09 Dec 2022 01:55:22 +0000 Received: from out-7.mta0.migadu.com ([91.218.175.7]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1p3SaE-000UfC-8H for linux-arm-kernel@lists.infradead.org; Fri, 09 Dec 2022 01:53:51 +0000 X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Oliver Upton To: Marc Zyngier , James Morse , Alexandru Elisei , Paolo Bonzini , Shuah Khan , Andrew Jones , Peter Gonda , Sean Christopherson Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, kvmarm@lists.linux.dev, Ricardo Koller , Oliver Upton , linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 7/7] KVM: selftests: Avoid infinite loop if ucall_alloc() fails Date: Fri, 9 Dec 2022 01:53:06 +0000 Message-Id: <20221209015307.1781352-8-oliver.upton@linux.dev> In-Reply-To: <20221209015307.1781352-1-oliver.upton@linux.dev> References: <20221209015307.1781352-1-oliver.upton@linux.dev> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221208_175350_468812_FD0C97F8 X-CRM114-Status: GOOD ( 12.71 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Guest assertions depend on successfully allocating a ucall structure. As such, the use of guest assertions when ucall_alloc() fails simply leads to an infinite loop in guest code. Use GUEST_UCALL_NONE() to indicate failure instead. Though not technically necessary, use a goto to have a single callsite and an associated comment about why assertions don't work here. It isn't perfect, at least the poor developer gets some signal out of the guest... Fixes: 426729b2cf2e ("KVM: selftests: Add ucall pool based implementation") Signed-off-by: Oliver Upton Reported-by: Oliver Upton Signed-off-by: Sean Christopherson --- tools/testing/selftests/kvm/lib/ucall_common.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/kvm/lib/ucall_common.c b/tools/testing/selftests/kvm/lib/ucall_common.c index 0cc0971ce60e..e8370da3de24 100644 --- a/tools/testing/selftests/kvm/lib/ucall_common.c +++ b/tools/testing/selftests/kvm/lib/ucall_common.c @@ -41,7 +41,8 @@ static struct ucall *ucall_alloc(void) struct ucall *uc; int i; - GUEST_ASSERT(ucall_pool); + if (!ucall_pool) + goto out; for (i = 0; i < KVM_MAX_VCPUS; ++i) { if (!test_and_set_bit(i, ucall_pool->in_use)) { @@ -51,7 +52,14 @@ static struct ucall *ucall_alloc(void) } } - GUEST_ASSERT(0); +out: + /* + * If the guest cannot grab a ucall structure from the pool then the + * only option to get out to userspace is a bare ucall. This is probably + * a good time to mention that guest assertions depend on ucalls with + * arguments too. + */ + GUEST_UCALL_NONE(); return NULL; }