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 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 DA10ED59D99 for ; Mon, 15 Dec 2025 02:57:57 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vUylx-0002WW-Ih; Sun, 14 Dec 2025 21:57:17 -0500 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 1vUylt-0002W6-Ba for qemu-devel@nongnu.org; Sun, 14 Dec 2025 21:57:13 -0500 Received: from mgamail.intel.com ([192.198.163.17]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vUylq-0003c1-5y for qemu-devel@nongnu.org; Sun, 14 Dec 2025 21:57:12 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1765767430; x=1797303430; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=afAcQzxeWF59zCX64zClLvrKT6yOR52rSHxbHr+YOMM=; b=I0xMWVFTO1S6r8umYnjQ3SyzbWxUef3LnKWJ2PvyQYkBJh8rHXEQHQet VTNg6GhvUTewingcyH3AQu3TbszHVUBCbqa8/gUh1SKK3WWtI/3p53sAO XCsPJQqYdfaOFsILZppOOzi8w/cEllbnNpFaTBoJ0Xrk0neghhAvDV02o XOCHASoGBMliIPwoO3kCYDzSdE+FZxtNWWih5LPKOdUzE4dTLNCPWu9EO 8Q/BsSbQ14R36QinS00ltv52pmP+JXPrZSPGAPVvv2UGf/+19aj3eUmP5 etcN5l5+qCRqYYJ6GU6/gM4wDc5LpBR/WsMODwaAekVIBYdpJHAcLD7aT g==; X-CSE-ConnectionGUID: miJFmSi0S5asK+jJgzs9kA== X-CSE-MsgGUID: iCkv3m+YRC+MXJ+nE9dPeA== X-IronPort-AV: E=McAfee;i="6800,10657,11642"; a="67551352" X-IronPort-AV: E=Sophos;i="6.21,148,1763452800"; d="scan'208";a="67551352" Received: from fmviesa001.fm.intel.com ([10.60.135.141]) by fmvoesa111.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Dec 2025 18:57:06 -0800 X-CSE-ConnectionGUID: 5G/D9F4DQcaU+1zEn6rX8A== X-CSE-MsgGUID: 3uf/zNm/RCymv8KM5WuUeQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,148,1763452800"; d="scan'208";a="228679385" Received: from unknown (HELO [10.238.0.255]) ([10.238.0.255]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Dec 2025 18:57:05 -0800 Message-ID: Date: Mon, 15 Dec 2025 10:57:02 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 7/9] hostmem: Support in-place guest memfd to back a VM To: Peter Xu Cc: qemu-devel@nongnu.org, Paolo Bonzini , David Hildenbrand , Alexey Kardashevskiy , Chenyi Qiang , Juraj Marcin , Fabiano Rosas References: <20251119172913.577392-1-peterx@redhat.com> <20251119172913.577392-8-peterx@redhat.com> <2ee4383c-f21f-448e-ac3f-2b621d687bf2@intel.com> Content-Language: en-US From: Xiaoyao Li In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=192.198.163.17; envelope-from=xiaoyao.li@intel.com; helo=mgamail.intel.com X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, HK_RANDOM_ENVFROM=0.001, HK_RANDOM_FROM=0.001, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, 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 On 12/13/2025 1:41 AM, Peter Xu wrote: >>>> please add the following check as I commented in v1: >>>> >>>> if (!kvm_enabled()) { >>>> error_setg(errp, "in-place guest-memfd requires KVM"); >>>> return false; >>>> } >>> IMHO it's redundant to set here, when kvm not enabled, >>> kvm_create_guest_memfd() should be a stub. >> No. The KVM stub is for the case where KVM is disable at compile time. >> >> The kvm_enabled() check here is for the case where users use different >> accelerators other than KVM, e.g., -accel tcg. > I thought the kvm-compiled case is already covered, at least the flags will > be 0 here: > > if (!kvm_guest_memfd_supported) { > error_setg(errp, "KVM does not support guest_memfd"); > return -1; > } > > So I can change below stub patch into this one, would it look better (so > that we'll provide explicit errors for all cases)? It looks good to me. > ===8<=== > commit 70012ceb70d3ffe624db33a8aeaaec581c7b4ccd > Author: Peter Xu > Date: Thu Dec 11 11:19:44 2025 -0500 > > kvm: Provide explicit error for kvm_create_guest_memfd() > > So that there will be a verbal string returned when kvm not enabled, or kvm > not compiled. > > Signed-off-by: Peter Xu > --- > accel/kvm/kvm-all.c | 5 +++++ > accel/stubs/kvm-stub.c | 1 + > 2 files changed, 6 insertions(+) > > diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c > index 68d57c1af0..c32fbcf9cc 100644 > --- a/accel/kvm/kvm-all.c > +++ b/accel/kvm/kvm-all.c > @@ -4492,6 +4492,11 @@ int kvm_create_guest_memfd(uint64_t size, uint64_t flags, Error **errp) > .flags = flags, > }; > > + if (!kvm_enabled()) { > + error_setg(errp, "guest-memfd requires KVM accelerator"); > + return -1; > + } > + > if (!kvm_guest_memfd_supported) { > error_setg(errp, "KVM does not support guest_memfd"); > return -1; > diff --git a/accel/stubs/kvm-stub.c b/accel/stubs/kvm-stub.c > index 73f04eb589..01b1d6285e 100644 > --- a/accel/stubs/kvm-stub.c > +++ b/accel/stubs/kvm-stub.c > @@ -123,6 +123,7 @@ bool kvm_hwpoisoned_mem(void) > > int kvm_create_guest_memfd(uint64_t size, uint64_t flags, Error **errp) > { > + error_setg(errp, "KVM is not enabled"); > return -ENOSYS; > } > ===8<=== > > Thanks,