From nobody Tue May 13 11:27:46 2025 Delivered-To: importer2@patchew.org Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer2=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1675263730026895.4469969629689; Wed, 1 Feb 2023 07:02:10 -0800 (PST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pNEBT-0003ZN-Cn; Wed, 01 Feb 2023 09:34:03 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pNE9m-0001Rc-ED for qemu-devel@nongnu.org; Wed, 01 Feb 2023 09:32:14 -0500 Received: from casper.infradead.org ([2001:8b0:10b:1236::1]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pNE9g-00036P-R5 for qemu-devel@nongnu.org; Wed, 01 Feb 2023 09:32:14 -0500 Received: from i7.infradead.org ([2001:8b0:10b:1:21e:67ff:fecb:7a92]) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1pNE9P-00CMap-7g; Wed, 01 Feb 2023 14:31:53 +0000 Received: from dwoodhou by i7.infradead.org with local (Exim 4.96 #2 (Red Hat Linux)) id 1pNE9P-007Jqg-0l; Wed, 01 Feb 2023 14:31:51 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Sender:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description; bh=R5rM5z7s7E4Lvv1hg+t9pUHA5+gYKakPc+YzUVV/gEg=; b=K/sSDefneW7SiAZ2e5vKJOzWu8 rRTCCgXiKu8DiBYQJy3vjM2CCQiEP7kF2ScyNQ1wM7J3aoFGa0B5sTAGmwAiGu8F+ToYNBaCiCtWq 4KrrhRaCCTi2e6PuiJtr3wkEQtO3GB4/snPfXx4d92eH2bwrDN5GYfLh347sYHHOhbLovB6xB2SS0 p1lRF8UD91ncSXvqTiBE2E+7eK5tmHnPbfjGcZ+htky7vao/CUh9hYcx788gp5568a2zE/OQrznLA i68XfdmQskXX4QsRyA8lvgbQlxXCzX1ayNDgjtVkEBymWCHPEpeSggMQOLrmhmBs4k453ZUTA0imv xUqgQLGw==; From: David Woodhouse To: Peter Maydell , qemu-devel@nongnu.org Cc: Paolo Bonzini , Paul Durrant , Joao Martins , Ankur Arora , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Thomas Huth , =?UTF-8?q?Alex=20Benn=C3=A9e?= , Juan Quintela , "Dr . David Alan Gilbert" , Claudio Fontana , Julien Grall , "Michael S. Tsirkin" , Marcel Apfelbaum , armbru@redhat.com Subject: [PATCH v10 12/59] i386/xen: Implement SCHEDOP_poll and SCHEDOP_yield Date: Wed, 1 Feb 2023 14:31:01 +0000 Message-Id: <20230201143148.1744093-13-dwmw2@infradead.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230201143148.1744093-1-dwmw2@infradead.org> References: <20230201143148.1744093-1-dwmw2@infradead.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer2=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: none client-ip=2001:8b0:10b:1236::1; envelope-from=BATV+8c5eeea0684575598b25+7101+infradead.org+dwmw2@casper.srs.infradead.org; helo=casper.infradead.org X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer2=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer2=patchew.org@nongnu.org X-ZohoMail-DKIM: fail (Header signature does not verify) X-ZM-MESSAGEID: 1675263740316100001 Content-Type: text/plain; charset="utf-8" From: David Woodhouse They both do the same thing and just call sched_yield. This is enough to stop the Linux guest panicking when running on a host kernel which doesn't intercept SCHEDOP_poll and lets it reach userspace. Signed-off-by: David Woodhouse Reviewed-by: Paul Durrant --- target/i386/kvm/xen-emu.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/target/i386/kvm/xen-emu.c b/target/i386/kvm/xen-emu.c index 4ed833656f..ebea27caf6 100644 --- a/target/i386/kvm/xen-emu.c +++ b/target/i386/kvm/xen-emu.c @@ -234,6 +234,19 @@ static bool kvm_xen_hcall_sched_op(struct kvm_xen_exit= *exit, X86CPU *cpu, err =3D schedop_shutdown(cs, arg); break; =20 + case SCHEDOP_poll: + /* + * Linux will panic if this doesn't work. Just yield; it's not + * worth overthinking it because with event channel handling + * in KVM, the kernel will intercept this and it will never + * reach QEMU anyway. The semantics of the hypercall explicltly + * permit spurious wakeups. + */ + case SCHEDOP_yield: + sched_yield(); + err =3D 0; + break; + default: return false; } --=20 2.39.0