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[35.230.65.123]) by smtp.gmail.com with ESMTPSA id iw13-20020a170903044d00b0015f4b7a012bsm565537plb.251.2022.06.17.17.09.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 17 Jun 2022 17:09:15 -0700 (PDT) Date: Sat, 18 Jun 2022 00:09:11 +0000 From: Sean Christopherson To: Colton Lewis Subject: Re: [PATCH 2/4] KVM: selftests: Increase UCALL_MAX_ARGS to 7 Message-ID: References: <20220615193116.806312-1-coltonlewis@google.com> <20220615193116.806312-3-coltonlewis@google.com> <20220616121006.ch6x7du6ycevjo5m@gator> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Cc: thuth@redhat.com, kvm@vger.kernel.org, maz@kernel.org, pbonzini@redhat.com, vkuznets@redhat.com, kvmarm@lists.cs.columbia.edu 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 On Fri, Jun 17, 2022, Colton Lewis wrote: > On Thu, Jun 16, 2022 at 02:10:06PM +0200, Andrew Jones wrote: > > We probably want to ensure all architectures are good with this. afaict, > > riscv only expects 6 args and uses UCALL_MAX_ARGS to cap the ucall inputs, > > for example. > > All architectures use UCALL_MAX_ARGS for that. Are you saying there > might be limitations beyond the value of the macro? If so, who should > verify whether this is ok? I thought there were architectural limitations too, but I believe I was thinking of vcpu_args_set(), where the number of params is limited by the function call ABI, e.g. the number of registers. Unless there's something really, really subtle going on, all architectures pass the actual ucall struct purely through memory. Actually, that code is ripe for deduplication, and amazingly it doesn't conflict with Colton's series. Patches incoming... _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm 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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7016CC43334 for ; Sat, 18 Jun 2022 00:09:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234931AbiFRAJR (ORCPT ); Fri, 17 Jun 2022 20:09:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60006 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230437AbiFRAJQ (ORCPT ); Fri, 17 Jun 2022 20:09:16 -0400 Received: from mail-pf1-x429.google.com (mail-pf1-x429.google.com [IPv6:2607:f8b0:4864:20::429]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 12CE753A5E for ; Fri, 17 Jun 2022 17:09:16 -0700 (PDT) Received: by mail-pf1-x429.google.com with SMTP id u37so5417348pfg.3 for ; Fri, 17 Jun 2022 17:09:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=rmREuzW95waiA3DDpOBKbzOCl6/bO3/zBUhkj2WSq9I=; b=YCP800zP22Elf3Ylaojub23i9i+c4DqKeQkNx5RkzWlB2guxY5lWBKf48hfbmaVQ/N eYGU19hBcx/GbITum/oZ8SXf9PmopWlcqw6oN1dmbAxSd/hhTpZFCC15vFDIIj3BGP/0 qvM1b6rK1d4jcutPEYVdVKRsphQhA0gcmF88AOdPZTKbsVXqN/63OoO/vXbqjvmxClro ddQiy7dpqMjtCcF0gkWPyZPF/Y64THzretyJqrXrL6lsiQzDYFKUdgoah4WnyM8iFglV VQAodr3sNg5DnUEiK0RF52Xp9/hR8JzLLs9y9rC6Rq2DBo+iYF+YA0KEL/65OkfsoXHs zwlQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=rmREuzW95waiA3DDpOBKbzOCl6/bO3/zBUhkj2WSq9I=; b=AgJ4VJnF3hWYoDzXkzHBlTvC/VhQfYnvXcJ6PKNsoG8HzSVSTcDc9iQpkiHjLU7pAF PwLk9WHcM0mG2Emokr2czf+5MjUb0t6OHW59CiEydzrVOalV7sZ8moe9hetaeGBSvYsL aZ3638A47N5WZdvus+1m8a+29d5KO2U547ty1Q0ZlxWJ1wol1fEINwYS7JiWg38YT27S 686/gh5xmAGz2sBSiNzD0R/oXFt9IfJImRd0F3eubIznz0EU8L9dufrxUoiQHfW2V4tX 6C3O5NE+apnYfx0m/2rNkLSMZAcFzqccBzagwAsjKZL/YOV+JsvG91I0ieQIat99vRMv 8Jkw== X-Gm-Message-State: AJIora+m+wptn+K61U0338ITvmJdpn3/bfKJy1ZjQuM/P7tmJudGwelV 5MCjL4xGPYXjZ3NcimYKUdINk2pdKdgkpQ== X-Google-Smtp-Source: AGRyM1ssehBTb8JKASbU9EaanhSrDN7Ob2S/Adon1xUDXwjcTBHM88tI85Trf31af1LqByg1k8MpIg== X-Received: by 2002:a05:6a00:450d:b0:524:d95b:d51d with SMTP id cw13-20020a056a00450d00b00524d95bd51dmr6985967pfb.29.1655510955383; Fri, 17 Jun 2022 17:09:15 -0700 (PDT) Received: from google.com (123.65.230.35.bc.googleusercontent.com. [35.230.65.123]) by smtp.gmail.com with ESMTPSA id iw13-20020a170903044d00b0015f4b7a012bsm565537plb.251.2022.06.17.17.09.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 17 Jun 2022 17:09:15 -0700 (PDT) Date: Sat, 18 Jun 2022 00:09:11 +0000 From: Sean Christopherson To: Colton Lewis Cc: Andrew Jones , kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, pbonzini@redhat.com, vkuznets@redhat.com, thuth@redhat.com, maz@kernel.org Subject: Re: [PATCH 2/4] KVM: selftests: Increase UCALL_MAX_ARGS to 7 Message-ID: References: <20220615193116.806312-1-coltonlewis@google.com> <20220615193116.806312-3-coltonlewis@google.com> <20220616121006.ch6x7du6ycevjo5m@gator> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Jun 17, 2022, Colton Lewis wrote: > On Thu, Jun 16, 2022 at 02:10:06PM +0200, Andrew Jones wrote: > > We probably want to ensure all architectures are good with this. afaict, > > riscv only expects 6 args and uses UCALL_MAX_ARGS to cap the ucall inputs, > > for example. > > All architectures use UCALL_MAX_ARGS for that. Are you saying there > might be limitations beyond the value of the macro? If so, who should > verify whether this is ok? I thought there were architectural limitations too, but I believe I was thinking of vcpu_args_set(), where the number of params is limited by the function call ABI, e.g. the number of registers. Unless there's something really, really subtle going on, all architectures pass the actual ucall struct purely through memory. Actually, that code is ripe for deduplication, and amazingly it doesn't conflict with Colton's series. Patches incoming...