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=-8.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=ham 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 F059BC433ED for ; Thu, 1 Apr 2021 05:43:02 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3FA2760FE9 for ; Thu, 1 Apr 2021 05:43:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3FA2760FE9 Authentication-Results: mail.kernel.org; dmarc=pass (p=none dis=none) header.from=ozlabs.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4F9sXh6czwz3c8s for ; Thu, 1 Apr 2021 16:43:00 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; secure) header.d=ozlabs.org header.i=@ozlabs.org header.a=rsa-sha256 header.s=201707 header.b=FOAfm1gx; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=ozlabs.org (client-ip=2401:3900:2:1::2; helo=ozlabs.org; envelope-from=paulus@ozlabs.org; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; secure) header.d=ozlabs.org header.i=@ozlabs.org header.a=rsa-sha256 header.s=201707 header.b=FOAfm1gx; dkim-atps=neutral Received: from ozlabs.org (bilbo.ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4F9sWQ5DWwz30MK for ; Thu, 1 Apr 2021 16:41:54 +1100 (AEDT) Received: by ozlabs.org (Postfix, from userid 1003) id 4F9sWH4tD8z9sWw; Thu, 1 Apr 2021 16:41:47 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ozlabs.org; s=201707; t=1617255707; bh=xpTr47Oj6tjUKhlk4O/qkZsmcdxnvdw69ZAkj/Dtjok=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=FOAfm1gxfn7uTLaiR9b6w36/PEwtILKm5qD5AV+3i35zLdWZtL9gnJlxmMNrH9Nqn rtMkLBiGdqONptXyG+WTu8vUkqcxkNQjHxHKHQdbc1oOZjiZEKfAa3TAyfnNDRV8HH Fe4hfs6yRAPsvoL5xACeeKf2k+mVjVj4YeHp2hb7PTj+93JgylV3qjQhF0guCSo5dL kh0ccP6q77DQbF1Sc960u8MGUq2rou5lF4m8bOLDupcMWR15lZRIAsiWaAdplnFkz5 8pizOEwN1pA1lZfhMqZ+xj7PVIVmQYHewVLgLY5oGRAIK/QsX/44rYflE4X/BFt6jo mnSoIWRcmg9mw== Date: Thu, 1 Apr 2021 16:32:50 +1100 From: Paul Mackerras To: Nicholas Piggin Subject: Re: [PATCH v4 13/46] KVM: PPC: Book3S 64: Move GUEST_MODE_SKIP test into KVM Message-ID: References: <20210323010305.1045293-1-npiggin@gmail.com> <20210323010305.1045293-14-npiggin@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210323010305.1045293-14-npiggin@gmail.com> X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Fabiano Rosas , linuxppc-dev@lists.ozlabs.org, kvm-ppc@vger.kernel.org, Daniel Axtens Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Tue, Mar 23, 2021 at 11:02:32AM +1000, Nicholas Piggin wrote: > Move the GUEST_MODE_SKIP logic into KVM code. This is quite a KVM > internal detail that has no real need to be in common handlers. > > Also add a comment explaining why this thing exists. [snip] > diff --git a/arch/powerpc/kvm/book3s_64_entry.S b/arch/powerpc/kvm/book3s_64_entry.S > index 7a039ea78f15..a5412e24cc05 100644 > --- a/arch/powerpc/kvm/book3s_64_entry.S > +++ b/arch/powerpc/kvm/book3s_64_entry.S > @@ -1,6 +1,7 @@ > /* SPDX-License-Identifier: GPL-2.0-only */ > #include > #include > +#include > #include > #include > #include > @@ -20,9 +21,12 @@ kvmppc_interrupt: > * guest R12 saved in shadow VCPU SCRATCH0 > * guest R13 saved in SPRN_SCRATCH0 > */ > -#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE > std r9,HSTATE_SCRATCH2(r13) > lbz r9,HSTATE_IN_GUEST(r13) > + cmpwi r9,KVM_GUEST_MODE_SKIP > + beq- .Lmaybe_skip > +.Lno_skip: > +#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE > cmpwi r9,KVM_GUEST_MODE_HOST_HV > beq kvmppc_bad_host_intr > #ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE > @@ -34,3 +38,48 @@ kvmppc_interrupt: > #else > b kvmppc_interrupt_pr > #endif It's a bit hard to see without more context, but I think that in the PR-only case (CONFIG_KVM_BOOK3S_HV_POSSIBLE undefined), this will corrupt R9. You need to restore R9 before the unconditional branch to kvmppc_interrupt_pr. (I realize this code gets modified further, but I'd rather not break bisection.) Paul.