From patchwork Wed Dec 21 01:05:49 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Woodhouse X-Patchwork-Id: 1718079 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=desiato.20200630 header.b=O25SFV64; 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 4NcFjX0NCWz23dC for ; Wed, 21 Dec 2022 12:10:08 +1100 (AEDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1p7na3-00049t-AO; Tue, 20 Dec 2022 20:07:35 -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 1p7nZO-0002vv-HU for qemu-devel@nongnu.org; Tue, 20 Dec 2022 20:06:54 -0500 Received: from desiato.infradead.org ([2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1p7nZM-0004HR-0x for qemu-devel@nongnu.org; Tue, 20 Dec 2022 20:06:53 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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=dgEpppW4ephV2U2qgEC8oXmP9Tpt2RSFcsN+dNSD0eQ=; b=O25SFV64zVWC/s6jTcDKqQWYI5 CSk/YtByLmKIEaIoqRbHsyohlvmMlxZ0PdBeDV9t1ZqvsMx3hxXzFMN7UVdmOHFVqO3+hN18hKfKJ dPjdKQwXK7jKgZh+kVM87iMIjQxoxIQr8E43sHNQ4avz40wVHz7YtIX6q9G5Gib6X6XvSoA+ol4Cm ryQXqyAfCxV2WeatQvEV74t39a/Z6GlwMgmHD939bIkVdgP9uUr/aCQ3d5Tk3AE8t8EPVYlQAxemO OoJObg055QmuBN6crXIPm1mpzW79OxGqb1HfyRohvvZE3z92naYtfn7gLIl9fqYVD9iS0e3Z7Vujb Zw9bmelw==; Received: from i7.infradead.org ([2001:8b0:10b:1:21e:67ff:fecb:7a92]) by desiato.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1p7nYx-00DDGP-1c; Wed, 21 Dec 2022 01:06:34 +0000 Received: from dwoodhou by i7.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1p7nYw-004CM1-Ha; Wed, 21 Dec 2022 01:06:26 +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 Subject: [RFC PATCH v4 13/47] i386/xen: Implement SCHEDOP_poll and SCHEDOP_yield Date: Wed, 21 Dec 2022 01:05:49 +0000 Message-Id: <20221221010623.1000191-14-dwmw2@infradead.org> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20221221010623.1000191-1-dwmw2@infradead.org> References: <20221221010623.1000191-1-dwmw2@infradead.org> MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by desiato.infradead.org. See http://www.infradead.org/rpr.html Received-SPF: none client-ip=2001:8b0:10b:1:d65d:64ff:fe57:4e05; envelope-from=BATV+7cc631609c1bd8ad3247+7059+infradead.org+dwmw2@desiato.srs.infradead.org; helo=desiato.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 --- target/i386/kvm/xen-emu.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/target/i386/kvm/xen-emu.c b/target/i386/kvm/xen-emu.c index 5f2b55ef10..80005ea527 100644 --- a/target/i386/kvm/xen-emu.c +++ b/target/i386/kvm/xen-emu.c @@ -227,6 +227,18 @@ 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 wWith event channel handling + * in KVM, the kernel will intercept this and it will never + * reach QEMU anyway. + */ + case SCHEDOP_yield: + sched_yield(); + err = 0; + break; + default: return false; }