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 X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 64DF6C55186 for ; Wed, 22 Apr 2020 10:35:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 43F7520780 for ; Wed, 22 Apr 2020 10:35:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587551703; bh=sByr9sNSa2X3ngNDdrYK6UPMYpAcHLw7TEu1niD7Wpc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=gwaDKr3KEg2Nm83vHs4PdgD3iRiDswkdynTmJWjDsvA5weouZ/8wXX3ULeJwF8u/r rBeuW9si56bDi5b547JpjT3no0XN1lfZREHPwlEAahhXUYEmjgW7SiULo1a3w3cQhN nDVZPO+g2a71XDFUIxVE8vBE4bqF9YiUny2rZOhc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731319AbgDVKfB (ORCPT ); Wed, 22 Apr 2020 06:35:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:60514 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730387AbgDVKX5 (ORCPT ); Wed, 22 Apr 2020 06:23:57 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A5F6820784; Wed, 22 Apr 2020 10:23:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587551037; bh=sByr9sNSa2X3ngNDdrYK6UPMYpAcHLw7TEu1niD7Wpc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DSL8vQuSLwNgjcaLUpUC1nBDqcqVTZD7Ky5hSo+2gSGqbj+mg7X8FYlgfAV+U85xj dvDQGOv5eF8i0wefh7hZk9VPJRaImSkcFaeJwiyyvy30qB0GRiWmr/4Bgz+J4NoLea jbO1gJXVFcnuvLCm8NupxcGs+LR56oHidGrj/p5o= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, linuxppc-dev@ozlabs.org, David Gibson , Paul Mackerras , Michael Roth , Sasha Levin Subject: [PATCH 5.6 076/166] KVM: PPC: Book3S HV: Fix H_CEDE return code for nested guests Date: Wed, 22 Apr 2020 11:56:43 +0200 Message-Id: <20200422095057.006842072@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200422095047.669225321@linuxfoundation.org> References: <20200422095047.669225321@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Michael Roth [ Upstream commit 1f50cc1705350a4697923203fedd7d8fb1087fe2 ] The h_cede_tm kvm-unit-test currently fails when run inside an L1 guest via the guest/nested hypervisor. ./run-tests.sh -v ... TESTNAME=h_cede_tm TIMEOUT=90s ACCEL= ./powerpc/run powerpc/tm.elf -smp 2,threads=2 -machine cap-htm=on -append "h_cede_tm" FAIL h_cede_tm (2 tests, 1 unexpected failures) While the test relates to transactional memory instructions, the actual failure is due to the return code of the H_CEDE hypercall, which is reported as 224 instead of 0. This happens even when no TM instructions are issued. 224 is the value placed in r3 to execute a hypercall for H_CEDE, and r3 is where the caller expects the return code to be placed upon return. In the case of guest running under a nested hypervisor, issuing H_CEDE causes a return from H_ENTER_NESTED. In this case H_CEDE is specially-handled immediately rather than later in kvmppc_pseries_do_hcall() as with most other hcalls, but we forget to set the return code for the caller, hence why kvm-unit-test sees the 224 return code and reports an error. Guest kernels generally don't check the return value of H_CEDE, so that likely explains why this hasn't caused issues outside of kvm-unit-tests so far. Fix this by setting r3 to 0 after we finish processing the H_CEDE. RHBZ: 1778556 Fixes: 4bad77799fed ("KVM: PPC: Book3S HV: Handle hypercalls correctly when nested") Cc: linuxppc-dev@ozlabs.org Cc: David Gibson Cc: Paul Mackerras Signed-off-by: Michael Roth Reviewed-by: David Gibson Signed-off-by: Paul Mackerras Signed-off-by: Sasha Levin --- arch/powerpc/kvm/book3s_hv.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 2cefd071b8483..c0c43a7338304 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -3616,6 +3616,7 @@ int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, if (trap == BOOK3S_INTERRUPT_SYSCALL && !vcpu->arch.nested && kvmppc_get_gpr(vcpu, 3) == H_CEDE) { kvmppc_nested_cede(vcpu); + kvmppc_set_gpr(vcpu, 3, 0); trap = 0; } } else { -- 2.20.1