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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 E9D88C282DE for ; Wed, 5 Jun 2019 08:59:08 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 78A3B2075C for ; Wed, 5 Jun 2019 08:59:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 78A3B2075C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id D90EE4A4BD; Wed, 5 Jun 2019 04:59:07 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id u4xNQDWF2p0F; Wed, 5 Jun 2019 04:59:06 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 991454A47E; Wed, 5 Jun 2019 04:59:06 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id EBE3E4A3B4 for ; Wed, 5 Jun 2019 04:59:05 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id rS0-nONXXL25 for ; Wed, 5 Jun 2019 04:59:04 -0400 (EDT) Received: from foss.arm.com (foss.arm.com [217.140.101.70]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 9B3224A389 for ; Wed, 5 Jun 2019 04:59:04 -0400 (EDT) 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 63AAFA78; Wed, 5 Jun 2019 01:59:03 -0700 (PDT) Received: from [10.1.197.45] (e112298-lin.cambridge.arm.com [10.1.197.45]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2E3ED3F690; Wed, 5 Jun 2019 01:59:02 -0700 (PDT) Subject: Re: [PATCH v1 1/6] KVM: arm64: Abstract the size of the HYP vectors pre-amble To: James Morse , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu References: <20190604144551.188107-1-james.morse@arm.com> <20190604144551.188107-2-james.morse@arm.com> From: Julien Thierry Message-ID: <34170392-528f-b57c-e50c-16eac02a5043@arm.com> Date: Wed, 5 Jun 2019 09:58:59 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20190604144551.188107-2-james.morse@arm.com> Content-Language: en-US Cc: Marc Zyngier , Catalin Marinas , Will Deacon X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu Hi James, On 04/06/2019 15:45, James Morse wrote: > The EL2 vector hardening feature causes KVM to generate vectors for > each type of CPU present in the system. The generated sequences already > do some of the early guest-exit work (i.e. saving registers). To avoid > duplication the generated vectors branch to the original vector just > after the preamble. This size is hard coded. > > Adding new instructions to the HYP vector causes strange side effects, > which are difficult to debug as the affected code is patched in at > runtime. > > Add KVM_VECTOR_PREAMBLE to tell kvm_patch_vector_branch() how big > the preamble is. The valid_vect macro can then validate this at > build time. > > Signed-off-by: James Morse > --- > arch/arm64/include/asm/kvm_asm.h | 6 ++++++ > arch/arm64/kvm/hyp/hyp-entry.S | 10 +++++++++- > arch/arm64/kvm/va_layout.c | 7 +++---- > 3 files changed, 18 insertions(+), 5 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h > index ff73f5462aca..9170c43b332f 100644 > --- a/arch/arm64/include/asm/kvm_asm.h > +++ b/arch/arm64/include/asm/kvm_asm.h > @@ -41,6 +41,12 @@ > {ARM_EXCEPTION_TRAP, "TRAP" }, \ > {ARM_EXCEPTION_HYP_GONE, "HYP_GONE" } > > +/* > + * Size of the HYP vectors preamble. kvm_patch_vector_branch() generates code > + * that jumps over this. > + */ > +#define KVM_VECTOR_PREAMBLE 4 Nit: I would use AARCH64_INSN_SIZE instead of 4 for the value if possible. Makes it clear what the value of the vectore preamble represent (and if we ad instruction we just multiply). Otherwise the patch seems a good improvement. Reviewed-by: Julien Thierry Thanks, -- Julien Thierry _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm