From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received-SPF: Pass (sender SPF authorized) identity=mailfrom; client-ip=2607:f8b0:4864:20::141; helo=mail-it1-x141.google.com; envelope-from=ard.biesheuvel@linaro.org; receiver=edk2-devel@lists.01.org Received: from mail-it1-x141.google.com (mail-it1-x141.google.com [IPv6:2607:f8b0:4864:20::141]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 4F77221188495 for ; Fri, 23 Nov 2018 05:45:50 -0800 (PST) Received: by mail-it1-x141.google.com with SMTP id h193so17993383ita.5 for ; Fri, 23 Nov 2018 05:45:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=AzqTicHCu/IOtvpM8S91SXzF0OX7mKax3lUcqCX7HtQ=; b=auLnH1jOvTT8Vh7FLNyUVJmrzLW434H+t8ElU2dJuoD5Sjf3f5ftIJUugrKovsNKo7 jIbUj6cfdX7iq8NWYF/4IgZQNBecqmdFSabHGiHG8LPplVuESEFhbj6M3bSpbCSNfxWb ilo00ORXYbPrW79LYJTe5Ja28IqSScqp3QSaQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=AzqTicHCu/IOtvpM8S91SXzF0OX7mKax3lUcqCX7HtQ=; b=SpAQRL14KdOgBEcfuldABXBptns4S4AkFmUmDwu2q1+K4ZU8G1RDirUJcamdHqgpnJ bT6IRYIziByJJoGCMUPwnvaniWQj+wMtyNqYOP1YI2D1yxrrugyEAhWAPKBWtGG7d+Mt WlRLkMXOnUoEN0tVfJq4Sicd2SBes6isv47BH6AmarsLtfnCj5MV2gbrAdEUWwhmVVKe WgJDJ3fE6aFBKw8MwHezarOV/z2i7UNSarMOzdanl4Md0rgEeqB4EsdmZTmyjAfoZ5Fz 6Xuw11y11kf4b5EK2d1I5A+t1jIx73Nymc8G7atMPmIKZclAtmYxjyF26G6G7FjWDzA9 8BgQ== X-Gm-Message-State: AGRZ1gKqVijg2VVd3Q4A+2FWEHA2wkhvmdGdkjLxUkjlrRBLAbmsVjK0 XtMnDE6f3T4pKivhj3dpZFCj7Ql/Clz+If+iI13wtiFy X-Google-Smtp-Source: AJdET5cLIDUbTtSAHdJea4Az8rj8yAXAgKF4o0SqReu/qowQKVQepY3acb5tNhG6y/uy0YR+OM3Xx26Hn/Xm8WQlyVU= X-Received: by 2002:a05:660c:4b:: with SMTP id p11mr13652260itk.71.1542980750327; Fri, 23 Nov 2018 05:45:50 -0800 (PST) MIME-Version: 1.0 References: <20181123121431.22353-1-ard.biesheuvel@linaro.org> <20181123121431.22353-6-ard.biesheuvel@linaro.org> <20181123133553.4o6rcbmebggn2ne7@hawk.localdomain> In-Reply-To: <20181123133553.4o6rcbmebggn2ne7@hawk.localdomain> From: Ard Biesheuvel Date: Fri, 23 Nov 2018 14:45:37 +0100 Message-ID: To: Andrew Jones Cc: "edk2-devel@lists.01.org" , Laszlo Ersek , Leif Lindholm , Auger Eric , =?UTF-8?Q?Philippe_Mathieu=2DDaud=C3=A9?= , Julien Grall Subject: Re: [PATCH 5/5] ArmVirtPkg: revert PcdPrePiCpuMemorySize to is default value of 48 X-BeenThere: edk2-devel@lists.01.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: EDK II Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 23 Nov 2018 13:45:51 -0000 Content-Type: text/plain; charset="UTF-8" On Fri, 23 Nov 2018 at 14:36, Andrew Jones wrote: > > On Fri, Nov 23, 2018 at 01:14:31PM +0100, Ard Biesheuvel wrote: > > Drop the PcdPrePiCpuMemorySize definitions that limit it to 40 > > bits on AArch64 targets. This is no longer appropriate now that > > KVM has been enhanced to permit any IPA space size permitted by > > the architecture. This means the value will revert back to its > > default of 48. > > If we're running on older KVM, then, since KVM just passes through > the host value of id_aa64mmfr0_el1, firmware will see whatever > the host supports and use that (I'm not sure if the 48-bit default > ever can come into play too). In either case, it probably doesn't > matter, because just like the guest kernel works today on older > KVM, as long as nothing is placed above 40 bits there isn't any > problem. Is that the case for edk2 too? > The value of 48 serves as a limit now, which makes sense given that 52-bit requires 64k pages, which we don't support. But as I said, it might make sense to permit the GCD space to describe that much, which is actually a nice side effect of the previous patch, which takes the value directly from the CPU system register on virt targets.