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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 14912C433DF for ; Mon, 8 Jun 2020 23:50:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D0C8820814 for ; Mon, 8 Jun 2020 23:50:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591660206; bh=Zx7Mas0ND3ZhnW4uZIFSFSxSsR4DZILpdmxi+NlRdbQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Q/+m43QovH14+tojZMfq0Crl8827u2+apIROBVGqmsxeqFHfJPGU+oIdy5J65Ffod kQE7LUEMoqxnaa33uJBxxp8ySPAqgaRenscP3HDP8cfGyH28q5AzEm3Vv4E8i+FrYD /ez4/HRPRdS1ZXhJTrMKfP0RgHxePo86peS8ikeY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732584AbgFHXuE (ORCPT ); Mon, 8 Jun 2020 19:50:04 -0400 Received: from mail.kernel.org ([198.145.29.99]:52030 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731484AbgFHXZ2 (ORCPT ); Mon, 8 Jun 2020 19:25:28 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2370D2068D; Mon, 8 Jun 2020 23:25:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591658728; bh=Zx7Mas0ND3ZhnW4uZIFSFSxSsR4DZILpdmxi+NlRdbQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=X7xQfRi+eKiNQ0gPq3/RJcAD9RTfBXRYV3uM1lDrlFDNY803poMpLlC6uFo6/v6yK 88EEf1tiku3xLj5q7oViIHnGn2ar+63l7CGfuZqXTcNA14IzokzjqLGXugDSKviKq3 dhUf5+RrNSdJzyHtneEz7Sguoe+mI5+aAOO5hU9k= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Jon Doron , Vitaly Kuznetsov , Roman Kagan , Paolo Bonzini , Sasha Levin , linux-doc@vger.kernel.org, kvm@vger.kernel.org Subject: [PATCH AUTOSEL 4.14 20/72] x86/kvm/hyper-v: Explicitly align hcall param for kvm_hyperv_exit Date: Mon, 8 Jun 2020 19:24:08 -0400 Message-Id: <20200608232500.3369581-20-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200608232500.3369581-1-sashal@kernel.org> References: <20200608232500.3369581-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jon Doron [ Upstream commit f7d31e65368aeef973fab788aa22c4f1d5a6af66 ] The problem the patch is trying to address is the fact that 'struct kvm_hyperv_exit' has different layout on when compiling in 32 and 64 bit modes. In 64-bit mode the default alignment boundary is 64 bits thus forcing extra gaps after 'type' and 'msr' but in 32-bit mode the boundary is at 32 bits thus no extra gaps. This is an issue as even when the kernel is 64 bit, the userspace using the interface can be both 32 and 64 bit but the same 32 bit userspace has to work with 32 bit kernel. The issue is fixed by forcing the 64 bit layout, this leads to ABI change for 32 bit builds and while we are obviously breaking '32 bit userspace with 32 bit kernel' case, we're fixing the '32 bit userspace with 64 bit kernel' one. As the interface has no (known) users and 32 bit KVM is rather baroque nowadays, this seems like a reasonable decision. Reviewed-by: Vitaly Kuznetsov Signed-off-by: Jon Doron Message-Id: <20200424113746.3473563-2-arilou@gmail.com> Reviewed-by: Roman Kagan Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin --- Documentation/virtual/kvm/api.txt | 2 ++ include/uapi/linux/kvm.h | 2 ++ 2 files changed, 4 insertions(+) diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index f67ed33d1054..81a8802cea88 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -3737,9 +3737,11 @@ EOI was received. #define KVM_EXIT_HYPERV_SYNIC 1 #define KVM_EXIT_HYPERV_HCALL 2 __u32 type; + __u32 pad1; union { struct { __u32 msr; + __u32 pad2; __u64 control; __u64 evt_page; __u64 msg_page; diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 27c62abb6c9e..efe8873943f6 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -189,9 +189,11 @@ struct kvm_hyperv_exit { #define KVM_EXIT_HYPERV_SYNIC 1 #define KVM_EXIT_HYPERV_HCALL 2 __u32 type; + __u32 pad1; union { struct { __u32 msr; + __u32 pad2; __u64 control; __u64 evt_page; __u64 msg_page; -- 2.25.1