From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.13]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 03F5C1F3B85 for ; Tue, 1 Sep 2026 06:03:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.13 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788242609; cv=none; b=ZhEnvxElQcACV2aNgjsGlja0VzJvVqFbJiGGMqiMEE1Z62WoLm7S2qH9OJPiSzDUKNubzPhLq+35XrRB35k63WRm71rVTKMilp+OvvJXxAVomXZ2ME/iNslrJqmDtWvsnuxzvKWXeMGa6XaSAMdoG+i6mgSMkDeqM9A/CDg+3pM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788242609; c=relaxed/simple; bh=ARmgaj61p3kmL6E2cd/ljeeaDDh/EdXOAT3NHk3aN9A=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=YMBwoL/TzSNlrQcVKExzrJEQvci1zv2kgQNxZBT6G3nhQSY211/U2MvVFz61X2Yh9SnUnknG4SDA5l1fIwBHUYOIw3Y9kZhyiGZDkoOdo3BNdAXnPZlQ4wx6ei4AGzuXULkBvYW7sDa4a77X/xW4B5dltKTma/PBF0FCHAdCuUk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=SaE3SZiX; arc=none smtp.client-ip=192.198.163.13 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="SaE3SZiX" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1788242607; x=1819778607; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=ARmgaj61p3kmL6E2cd/ljeeaDDh/EdXOAT3NHk3aN9A=; b=SaE3SZiX+aLXn16Who3HmZxFuJBByktUxroayy0Wpho3lgL+JFxmseUa 1o2Qr8YkW1w/aX380c6u9/+PoZJt23JFsXlwbe8hmIQ21OfpwVNX7t540 n4ueyuGO6P6PcbpBzkxZTwujahq3J6Ba52K+cT+phITgBsK5KQV8yiGKE za62xTdRHsVQ4ZVoe6hP0NQS2+73FxDeavZ9OCbGmabWYMVLht8txHKXu Dj5ImWy6pwOX6tk/Hy5zfzSpxD3i9KdyvFltdlcB47EbYNVpN0UWM/+5d M77oHFB7IGAzuX3/8Bl+D61c2SY3BOPGc+XvVQ+TuHLhvhTAOl/IsRo43 Q==; X-CSE-ConnectionGUID: 0mD1wBbXQ7yLpEkTTEhIMA== X-CSE-MsgGUID: luCCFM6GS0a7GDpp7hGn5A== X-IronPort-AV: E=McAfee;i="6800,10657,11892"; a="91172903" X-IronPort-AV: E=Sophos;i="6.25,255,1779174000"; d="scan'208";a="91172903" Received: from orviesa010.jf.intel.com ([10.64.159.150]) by fmvoesa107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Aug 2026 23:03:26 -0700 X-CSE-ConnectionGUID: bYit0Gl3Riyd4gPOve6x6w== X-CSE-MsgGUID: 1yQaa3xhSvmxjr9nZDoJXg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,255,1779174000"; d="scan'208";a="267675063" Received: from kniemiec-mobl1.ger.corp.intel.com (HELO localhost) ([10.245.244.192]) by orviesa010-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Aug 2026 23:03:25 -0700 Date: Tue, 1 Sep 2026 09:03:22 +0300 From: Tony Lindgren To: sashiko-reviews@lists.linux.dev Cc: kvm@vger.kernel.org Subject: Re: [RFC PATCH v2 2/4] KVM: x86: Add optional KVM_CAP_LIVE_MIGRATION and KVM_MIGRATE_CMD Message-ID: References: <20260831071304.762939-1-tony.lindgren@linux.intel.com> <20260831071304.762939-3-tony.lindgren@linux.intel.com> <20260831072311.CF2DA1F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260831072311.CF2DA1F000E9@smtp.kernel.org> On Mon, Aug 31, 2026 at 07:23:11AM +0000, sashiko-bot@kernel.org wrote: > Author: Tony Lindgren > > --- a/arch/x86/kvm/x86.c > > +++ b/arch/x86/kvm/x86.c > > @@ -7614,6 +7617,28 @@ int kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) > > r = kvm_vm_ioctl_set_msr_filter(kvm, &filter); > > break; > > } > > + case KVM_MIGRATE_CMD: { > > + struct kvm_migrate_cmd cmd; > > + > > + if (!kvm_x86_ops.migrate_cmd || > > + !kvm_x86_call(cap_live_migration)(kvm)) > > + return -ENOTTY; > > + > > + if (copy_from_user(&cmd, argp, sizeof(cmd))) > > + return -EFAULT; > > + > > + if (cmd.reserved || cmd.buf.reserved) > > + return -EINVAL; > > [Severity: High] > Does this code also need to validate that the new flags field is zero? > > If uninitialized memory or garbage is passed by userspace in cmd.flags, it > will currently be silently ignored. When a future kernel introduces a new > flag, old userspace applications passing uninitialized flags will inadvertently > enable it, which could permanently break backwards compatibility. Could be zero, or we could check for the known flags. We are currently using the following flags for KVM_MIGRATE_CMD sub-commands for TDX: 1. KVM_MIGRATE_SETUP ==================== TDX_MIGRATE_SETUP_SESSION exchange the migration keys TDX_MIGRATE_IMMUTABLE_STATE transfer the TDX immutable state 2. KVM_MIGRATE_ITERATION ======================== TDX_MIGRATE_IN_ORDER_DONE end the in-order migration 3. KVM_MIGRATE_STOP_AND_COPY ============================ TDX_MIGRATE_STOP_COPY_PAUSE pause the TD TDX_MIGRATE_STOP_COPY_TD_STATE transfer the mutable TD state 4. KVM_MIGRATE_END ================== TDX_MIGRATE_ABORT abort migration Maybe all the above TDX specific flags could be turned into generic flags for the sub-commands.