From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail02.groups.io (mail02.groups.io [66.175.222.108]) by spool.mail.gandi.net (Postfix) with ESMTPS id 68759D801B3 for ; Thu, 22 Feb 2024 01:34:35 +0000 (UTC) DKIM-Signature: a=rsa-sha256; bh=ghUg2o6qbRmD7dlZL2wB+5Vkk4ytidm8dn1+2IwTR+c=; c=relaxed/simple; d=groups.io; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From:In-Reply-To:Precedence:List-Subscribe:List-Help:Sender:List-Id:Mailing-List:Delivered-To:Reply-To:List-Unsubscribe-Post:List-Unsubscribe:Content-Language:Content-Type:Content-Transfer-Encoding; s=20140610; t=1708565674; v=1; b=L0DNkZ/NBpEuE/29wU98i+kPTeEChJKEg20bR52zBTXG6+eFzNhOYV7GsiKzVHcEaEUL+3KH e2ICcKYNKAONZeWr5UWX8vfGJnDqSvgIqZ825we/R+7/4LsKYvclra/DCKWbELBB/Yrqag5icp7 216byEsbzF5sNRJVIfrBb4rU= X-Received: by 127.0.0.2 with SMTP id QdpqYY7687511xjZWhdZ60es; Wed, 21 Feb 2024 17:34:34 -0800 X-Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by mx.groups.io with SMTP id smtpd.web10.3594.1708565673440347210 for ; Wed, 21 Feb 2024 17:34:33 -0800 X-Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-225-PnQ5e6O-OiKby1r83adAtA-1; Wed, 21 Feb 2024 20:34:28 -0500 X-MC-Unique: PnQ5e6O-OiKby1r83adAtA-1 X-Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (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 mimecast-mx02.redhat.com (Postfix) with ESMTPS id 637EB185A780; Thu, 22 Feb 2024 01:34:28 +0000 (UTC) X-Received: from [10.39.192.46] (unknown [10.39.192.46]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4C6B32864; Thu, 22 Feb 2024 01:34:27 +0000 (UTC) Message-ID: Date: Thu, 22 Feb 2024 02:34:26 +0100 MIME-Version: 1.0 Subject: Re: [edk2-devel] [PATCH v2 5/5] UefiCpuPkg/MpInitLib: Add support for multiple HOBs to SaveCpuMpData() To: devel@edk2.groups.io, kraxel@redhat.com, ray.ni@intel.com Cc: Oliver Steffen , "Kumar, Rahul R" References: <20240220174939.1288689-1-kraxel@redhat.com> <20240220174939.1288689-6-kraxel@redhat.com> From: "Laszlo Ersek" In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Precedence: Bulk List-Subscribe: List-Help: Sender: devel@edk2.groups.io List-Id: Mailing-List: list devel@edk2.groups.io; contact devel+owner@edk2.groups.io Reply-To: devel@edk2.groups.io,lersek@redhat.com List-Unsubscribe-Post: List-Unsubscribe=One-Click List-Unsubscribe: X-Gm-Message-State: Kuq0cfuanTxkAmBFG2XzyTVHx7686176AA= Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-GND-Status: LEGIT Authentication-Results: spool.mail.gandi.net; dkim=pass header.d=groups.io header.s=20140610 header.b="L0DNkZ/N"; spf=pass (spool.mail.gandi.net: domain of bounce@groups.io designates 66.175.222.108 as permitted sender) smtp.mailfrom=bounce@groups.io; dmarc=fail reason="SPF not aligned (relaxed), DKIM not aligned (relaxed)" header.from=redhat.com (policy=none) On 2/21/24 11:24, Gerd Hoffmann wrote: > On Wed, Feb 21, 2024 at 03:48:25AM +0000, Ni, Ray wrote: >>> >>> + MaxCpusPerHob =3D (MAX_UINT16 - sizeof (EFI_HOB_GUID_TYPE) - sizeof >>> (MP_HAND_OFF)) / sizeof (PROCESSOR_HAND_OFF); >> >> Above formula assumes the maximum HOB length could be 0xFFFF. >=20 > Which is IMHO correct. >=20 >> But actually the maximum HOB length could be only 0xFFF8 because >> PeiCore::PeiCreateHob() contains following logic: >> >> if (0x10000 - Length <=3D 0x7) { >> return EFI_INVALID_PARAMETER; >> } >=20 > That Length is the *data* size, the HOB header is not included. >=20 > The "- sizeof (EFI_HOB_GUID_TYPE)" in the formula above accounts the > space needed for HOB header and GUID. >From the patch: MaxCpusPerHob =3D (MAX_UINT16 - sizeof (EFI_HOB_GUID_TYPE) - sizeof (MP_H= AND_OFF)) / sizeof (PROCESSOR_HAND_OFF); ... CpusInHob =3D MIN (CpuMpData->CpuCount - HobBase, MaxCpusPerHob); MpHandOffSize =3D sizeof (MP_HAND_OFF) + sizeof (PROCESSOR_HAND_OFF) * Cp= usInHob; MpHandOff =3D (MP_HAND_OFF *)BuildGuidHob (&mMpHandOffGuid, MpHandOff= Size); Assuming that the division is exact, and that the MIN selects MaxCpusPerHob= for CpusInHob, we get: MpHandOffSize =3D sizeof (MP_HAND_OFF) + sizeof (PROCESSOR_HAND_OFF) * (M= AX_UINT16 - sizeof (EFI_HOB_GUID_TYPE) - sizeof (MP_HAND_OFF)) / sizeof (PR= OCESSOR_HAND_OFF); the multiplication and the division cancel out (again, assuming exact divis= ion): MpHandOffSize =3D sizeof (MP_HAND_OFF) + (MAX_UINT16 - sizeof (EFI_HOB_GU= ID_TYPE) - sizeof (MP_HAND_OFF)); the sizeof (MP_HAND_OFF) addition and subtraction cancel out: MpHandOffSize =3D MAX_UINT16 - sizeof (EFI_HOB_GUID_TYPE); then we get: MpHandOff =3D (MP_HAND_OFF *)BuildGuidHob (&mMpHandOffGuid, MAX_UINT1= 6 - sizeof (EFI_HOB_GUID_TYPE)); Inside BuildGuidHob() [MdePkg/Library/PeiHobLib/HobLib.c], we get DataLength =3D MAX_UINT16 - sizeof (EFI_HOB_GUID_TYPE); and further ASSERT (DataLength <=3D (0xFFF8 - sizeof (EFI_HOB_GUID_TYPE))); Substituting for DataLength, ASSERT (MAX_UINT16 - sizeof (EFI_HOB_GUID_TYPE) <=3D (0xFFF8 - sizeof (EF= I_HOB_GUID_TYPE))); which is ASSERT (MAX_UINT16 <=3D 0xFFF8); which fails. So, as Ray says, and as I wrote under v1, you need to use 0xFFF8 here, not = MAX_UINT16. ... Under v1, I wrote CpusPerHob =3D (0xFFE0 - sizeof (MP_HAND_OFF)) / sizeof (PROCESSOR_HAND_O= FF); If you want to make "sizeof (EFI_HOB_GUID_TYPE)" -- 24 bytes -- explicit in= that subtraction, that is fine, but then we just get back to 0xFFF8: CpusPerHob =3D (0xFFF8 - sizeof (EFI_HOB_GUID_TYPE) - sizeof (MP_HAND_OFF= )) / sizeof (PROCESSOR_HAND_OFF); Laszlo -=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#115766): https://edk2.groups.io/g/devel/message/115766 Mute This Topic: https://groups.io/mt/104472313/7686176 Group Owner: devel+owner@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [rebecca@openfw.io] -=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D-