From patchwork Mon Jan 16 21:57:26 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Woodhouse X-Patchwork-Id: 1727301 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: legolas.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; secure) header.d=infradead.org header.i=@infradead.org header.a=rsa-sha256 header.s=casper.20170209 header.b=IziNa/z0; dkim-atps=neutral Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4NwmMB5GH0z23fT for ; Tue, 17 Jan 2023 09:06:30 +1100 (AEDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pHXVC-0006yK-8l; Mon, 16 Jan 2023 16:58:50 -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 1pHXUs-0006kt-Ou for qemu-devel@nongnu.org; Mon, 16 Jan 2023 16:58:30 -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 1pHXUn-0003Zm-3d for qemu-devel@nongnu.org; Mon, 16 Jan 2023 16:58:30 -0500 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=B03isugXQLVjWqCEicNmCW7s0TWRtiAUY3UBFtx9Ry4=; b=IziNa/z0f0Vu/El7hLfk3JSRj6 bogWmutNAcynRfkA999KAvAIkZBMcS0lbX/Y8n7E8vkQVGTy4XIoSakTZ1zocy5QlI4g1wMUp1QVj JBqnz5lHwni5ji3TCo882VUMe2u6grsGr4C6/P1LdTpBQIdsq+uMQ01HEbCyp95b/kQc/ZU3XskNz 7H+KM1cqJ5teLJ90RTq1PSG9JsFTZ4IbSaKy/9sKRki3+fGEvCIIzlHbDjZfzStSjp55VnIbwk3qD /ySbyZKjplmikTZ03OOmUKI9V3Kg4DSjVRlrK5r9QF3RJMudxhaND3xg2mj/wOiVgq1+lL9oreNpS 4v4q39PA==; 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 1pHXUj-0097V9-P6; Mon, 16 Jan 2023 21:58:26 +0000 Received: from dwoodhou by i7.infradead.org with local (Exim 4.96 #2 (Red Hat Linux)) id 1pHXUW-004iOQ-0A; Mon, 16 Jan 2023 21:58:08 +0000 From: David Woodhouse To: qemu-devel@nongnu.org Cc: Paolo Bonzini , Paul Durrant , Joao Martins , Ankur Arora , =?utf-8?q?Philippe_Mathieu-Daud?= =?utf-8?q?=C3=A9?= , Thomas Huth , =?utf-8?q?Alex_Benn=C3=A9e?= , Juan Quintela , "Dr . David Alan Gilbert" , Claudio Fontana , Julien Grall , "Michael S. Tsirkin" , Marcel Apfelbaum , armbru@redhat.com Subject: [PATCH v7 12/51] i386/xen: Implement SCHEDOP_poll and SCHEDOP_yield Date: Mon, 16 Jan 2023 21:57:26 +0000 Message-Id: <20230116215805.1123514-13-dwmw2@infradead.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230116215805.1123514-1-dwmw2@infradead.org> References: <20230116215805.1123514-1-dwmw2@infradead.org> MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Received-SPF: none client-ip=2001:8b0:10b:1236::1; envelope-from=BATV+fb0b8ce1ba8490165fd5+7085+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+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org 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 5f2b55ef10..6584a15bab 100644 --- a/target/i386/kvm/xen-emu.c +++ b/target/i386/kvm/xen-emu.c @@ -227,6 +227,19 @@ static bool kvm_xen_hcall_sched_op(struct kvm_xen_exit *exit, X86CPU *cpu, err = schedop_shutdown(cs, arg); break; + 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 = 0; + break; + default: return false; }