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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 3EAF0C43381 for ; Fri, 22 Feb 2019 16:04:14 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 067E92075C for ; Fri, 22 Feb 2019 16:04:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="OLdaeCIm" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 067E92075C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=zDd+gfongbFlFT2bxmdCWWgPXmGEM6fzSzDMomhcY0c=; b=OLdaeCImjfMW+qNKXn7ObewgC P2rxoSQeQuzcrgObidgUk8c90dZtWuaFv4Cp4kMPhwULj4fJ6o4d8eBcwX4Ia96NX0dr28Wjczaml yaJrZ+OrcWgex9Bvm0eNslHzbT4NOyH5ZNrkvKy9CvGh3E7i0g0g9Z+aViO2HKmjtm5EzsFG0p8kU PFaCWEUY+9ZV19D/Jn0KRVuQ+AHNl9QDpQBbOrRBM32VHZyjoTkuAyNvv45m4oa/KQkazF9ylp37v b3isXyjLZxYJ/3fofAYcLBSAeFTix3QByXlWSU4SV22MiLD47w5/Db6+4P+NKW/QaeDflxmmPvxxq ydUW2dWrQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gxDJ4-00075L-5x; Fri, 22 Feb 2019 16:04:10 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gxDJ0-00070z-Bo for linux-arm-kernel@lists.infradead.org; Fri, 22 Feb 2019 16:04:07 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 7D8CF80D; Fri, 22 Feb 2019 08:04:05 -0800 (PST) Received: from [10.1.196.50] (e108454-lin.cambridge.arm.com [10.1.196.50]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8ACAF3F575; Fri, 22 Feb 2019 08:04:03 -0800 (PST) Subject: Re: [PATCH v5 11/26] KVM: arm64: Extend reset_unknown() to handle mixed RES0/UNKNOWN registers To: Dave Martin , kvmarm@lists.cs.columbia.edu References: <1550519559-15915-1-git-send-email-Dave.Martin@arm.com> <1550519559-15915-12-git-send-email-Dave.Martin@arm.com> From: Julien Grall Message-ID: Date: Fri, 22 Feb 2019 16:04:01 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <1550519559-15915-12-git-send-email-Dave.Martin@arm.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190222_080406_418598_F2958C70 X-CRM114-Status: GOOD ( 23.53 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Okamoto Takayuki , Christoffer Dall , Ard Biesheuvel , Marc Zyngier , Catalin Marinas , Will Deacon , Zhang Lei , =?UTF-8?Q?Alex_Benn=c3=a9e?= , linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Dave, On 18/02/2019 19:52, Dave Martin wrote: > The reset_unknown() system register helper initialises a guest > register to a distinctive junk value on vcpu reset, to help expose > and debug deficient register initialisation within the guest. > > Some registers such as the SVE control register ZCR_EL1 contain a > mixture of UNKNOWN fields and RES0 bits. For these, > reset_unknown() does not work at present, since it sets all bits to > junk values instead of just the wanted bits. > > There is no need to craft another special helper just for that, > since reset_unknown() almost does the appropriate thing anyway. > This patch takes advantage of the unused val field in struct > sys_reg_desc to specify a mask of bits that should be initialised > to zero instead of junk. > > All existing users of reset_unknown() do not (and should not) > define a value for val, so they will implicitly set it to zero, > resulting in all bits being made UNKNOWN by this function: thus, > this patch makes no functional change for currently defined > registers. > > Future patches will make use of non-zero val. > > Signed-off-by: Dave Martin Reviewed-by: Julien Grall Cheers, > --- > arch/arm64/kvm/sys_regs.h | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/kvm/sys_regs.h b/arch/arm64/kvm/sys_regs.h > index 3b1bc7f..174ffc0 100644 > --- a/arch/arm64/kvm/sys_regs.h > +++ b/arch/arm64/kvm/sys_regs.h > @@ -56,7 +56,12 @@ struct sys_reg_desc { > /* Index into sys_reg[], or 0 if we don't need to save it. */ > int reg; > > - /* Value (usually reset value) */ > + /* > + * Value (usually reset value) > + * For reset_unknown, each bit set to 1 in val is treated as > + * RES0 in the register: the corresponding register bit is > + * reset to 0 instead of "unknown". > + */ > u64 val; > > /* Custom get/set_user functions, fallback to generic if NULL */ > @@ -92,7 +97,9 @@ static inline void reset_unknown(struct kvm_vcpu *vcpu, > { > BUG_ON(!r->reg); > BUG_ON(r->reg >= NR_SYS_REGS); > - __vcpu_sys_reg(vcpu, r->reg) = 0x1de7ec7edbadc0deULL; > + > + /* If non-zero, r->val specifies which register bits are RES0: */ > + __vcpu_sys_reg(vcpu, r->reg) = 0x1de7ec7edbadc0deULL & ~r->val; > } > > static inline void reset_val(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r) > -- Julien Grall _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel