From patchwork Sun Sep 29 18:06:58 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ard Biesheuvel X-Patchwork-Id: 13815186 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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id BB248CF6495 for ; Sun, 29 Sep 2024 18:08:47 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1suyKl-0003k3-39; Sun, 29 Sep 2024 14:07:51 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1suyKa-0003Xc-Nb for qemu-devel@nongnu.org; Sun, 29 Sep 2024 14:07:41 -0400 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1suyKZ-0008Ul-1a for qemu-devel@nongnu.org; Sun, 29 Sep 2024 14:07:40 -0400 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 48B7E5C35DE; Sun, 29 Sep 2024 18:07:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1307CC4CEC5; Sun, 29 Sep 2024 18:07:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1727633258; bh=zugxR724dlw5HRjvz+NLeFunLq6E0krl84kUd9AxbSk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=o/6tOhddQLXy22KKCtRvIH1q4jyjRlkiwLODq8IrHvnGVPEEf75Jk/gDgIJhMQ++g DzgT03CFq8MKsujusipgk/qihC6mGhGw2H5wwnGtW9bek4di5nwsM8D6LsjVfl0Ooi uWmofnICXJAghxSHXMiJfBcJuO3TC0njWXreq/cZr3TyYRBEt97/lzZYbnp4jPgBid kpwcCDl3l1Kgt9dsKmnitjcdhy1kUn/MR6kQZZCWZK08wKTEjfUgFXjQhMOmg62Ih+ qcVrvW9L/BHoie8s6R/DvbFolTb6d+dgrPcEqLupVF6+G6xgy9B672rMKkULJg/IRl aHAvjHC7RQ6Vw== From: Ard Biesheuvel To: qemu-devel@nongnu.org Cc: pbonzini@redhat.com, Ard Biesheuvel Subject: [PATCH v2 2/2] hw/x86: Always treat the PVH entrypoint as a 32-bit LE field Date: Sun, 29 Sep 2024 20:06:58 +0200 Message-Id: <20240929180659.3598-3-ardb@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20240929180659.3598-1-ardb@kernel.org> References: <20240929180659.3598-1-ardb@kernel.org> MIME-Version: 1.0 Received-SPF: pass client-ip=2604:1380:4641:c500::1; envelope-from=ardb@kernel.org; helo=dfw.source.kernel.org X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.095, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org The PVH entrypoint is entered in 32-bit mode, and is documented as being a 32-bit field. Linux happens to widen the field in the ELF note to 64 bits so treating it as a 64-bit field works for booting the kernel. However, Xen documents the ELF note with the following example ELFNOTE(Xen, XEN_ELFNOTE_PHYS32_ENTRY, .long, xen_start32) and uses .long in the code as well, and so reading more than 32 bits here is risky. And dereferencing a size_t* in portable code is just bizarre, so let's use a uint32_t specifically in all cases here. While at it, read the field as little-endian explicitly, so things work as expected on big endian hosts too. Signed-off-by: Ard Biesheuvel --- hw/i386/x86-common.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/hw/i386/x86-common.c b/hw/i386/x86-common.c index 992ea1f25e..44e5c365f1 100644 --- a/hw/i386/x86-common.c +++ b/hw/i386/x86-common.c @@ -539,7 +539,7 @@ DeviceState *ioapic_init_secondary(GSIState *gsi_state) */ static uint64_t read_pvh_start_addr(void *arg1, void *arg2, bool is64) { - size_t *elf_note_data_addr; + void *elf_note_data_addr; /* Check if ELF Note header passed in is valid */ if (arg1 == NULL) { @@ -555,8 +555,6 @@ static uint64_t read_pvh_start_addr(void *arg1, void *arg2, bool is64) elf_note_data_addr = ((void *)nhdr64) + nhdr_size64 + QEMU_ALIGN_UP(nhdr_namesz, phdr_align); - - pvh_start_addr = *elf_note_data_addr; } else { struct elf32_note *nhdr32 = (struct elf32_note *)arg1; uint32_t nhdr_size32 = sizeof(struct elf32_note); @@ -566,10 +564,9 @@ static uint64_t read_pvh_start_addr(void *arg1, void *arg2, bool is64) elf_note_data_addr = ((void *)nhdr32) + nhdr_size32 + QEMU_ALIGN_UP(nhdr_namesz, phdr_align); - - pvh_start_addr = *(uint32_t *)elf_note_data_addr; } + pvh_start_addr = ldl_le_p(elf_note_data_addr); return pvh_start_addr; }