From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.12]) (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 9A7B6270EBC; Fri, 29 Aug 2025 09:52:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.12 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756461169; cv=none; b=NwOVNO8ZrjWOzbqgIS4xX8w/MTeYfquPncbycVXoiC1t14NGbUih9M2lZgxpHWWPei9enD5DtlF7vTASDks9oBGhMrCyNfjnWOui21fzI4BGJvPFrNnD5IvWdtkMPJRBl/uxi1RLOBwosHadYe0DKisK1DxNA1Kd3aOgmtK8cqk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756461169; c=relaxed/simple; bh=T5E7MUA3xyACQTwyysefk6cF5tOE6ceeLrQtL6q37gw=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=lth2xRPAnPxGOWwpu724iFZ6XXnrKskCoSkPShWlj1sZEUj08nq9dO6VkZidClUjasMeELGXhXH3M4iP2VGnuQOmH4idQUP7hBf6XWgl2Z9ijubajTCy9wf+l2Z4ayO8HZMlVzJQfuCAsW+LR1LmvHFLtncrxXfmhPou2TCe6wc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=kA9PXWyL; arc=none smtp.client-ip=192.198.163.12 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none 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="kA9PXWyL" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1756461168; x=1787997168; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=T5E7MUA3xyACQTwyysefk6cF5tOE6ceeLrQtL6q37gw=; b=kA9PXWyLs5qJG/1E2NYxGK53gWrq6VLT1MMWtpkTf13EGWqgNrd760qJ VL60Sw/BnC8nJE9fD7XZD2vrEGeNYIqmjWQlcu/xhp7OcV50nDkhdq0ZE Y/zjIP/VtZ7oG6urhznNTiFgeyqg5y2RY7PfizMOgru2JOxfl1CI2VgBM B2w3ZCthZ/7XCANDasR4aKkS1+FaSRIlfeylnYKfIlCGO9MWrxQc2rXtD v4/Z/WZAR3cyy/bpl3M9Emttoq6SAJhSl4hnsXK1fMvcoo5ZnRzTPr/Ce V+KR6H9vmLsoPMtaRPG2ioAnnBw3udcb4TIJuosnZzBjyQEgeVeuxklCR w==; X-CSE-ConnectionGUID: rT07jn04QO2VkLGOwg97lQ== X-CSE-MsgGUID: 0VjzFN5cTkqgEmvskHKIXA== X-IronPort-AV: E=McAfee;i="6800,10657,11536"; a="62561240" X-IronPort-AV: E=Sophos;i="6.18,221,1751266800"; d="scan'208";a="62561240" Received: from orviesa004.jf.intel.com ([10.64.159.144]) by fmvoesa106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Aug 2025 02:52:47 -0700 X-CSE-ConnectionGUID: cEimaGQsSfOmw3S0IybNNg== X-CSE-MsgGUID: USiDBVVKRbS9jZfizR0wxg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.18,221,1751266800"; d="scan'208";a="174717959" Received: from unknown (HELO [10.238.0.107]) ([10.238.0.107]) by orviesa004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Aug 2025 02:52:44 -0700 Message-ID: <0f4225bf-92fd-48a2-8015-65da12a135c8@linux.intel.com> Date: Fri, 29 Aug 2025 17:52:41 +0800 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v2 09/18] KVM: TDX: Avoid a double-KVM_BUG_ON() in tdx_sept_zap_private_spte() To: Sean Christopherson Cc: Paolo Bonzini , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Ira Weiny , Kai Huang , Michael Roth , Yan Zhao , Vishal Annapurve , Rick Edgecombe , Ackerley Tng References: <20250829000618.351013-1-seanjc@google.com> <20250829000618.351013-10-seanjc@google.com> Content-Language: en-US From: Binbin Wu In-Reply-To: <20250829000618.351013-10-seanjc@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 8/29/2025 8:06 AM, Sean Christopherson wrote: > Return -EIO immediately from tdx_sept_zap_private_spte() if the number of > to-be-added pages underflows, so that the following "KVM_BUG_ON(err, kvm)" > isn't also triggered. Isolating the check from the "is premap error" > if-statement will also allow adding a lockdep assertion that premap errors > are encountered if and only if slots_lock is held. > > Reviewed-by: Rick Edgecombe > Signed-off-by: Sean Christopherson Reviewed-by: Binbin Wu > --- > arch/x86/kvm/vmx/tdx.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c > index 07f9ad1fbfb6..cafd618ca43c 100644 > --- a/arch/x86/kvm/vmx/tdx.c > +++ b/arch/x86/kvm/vmx/tdx.c > @@ -1724,8 +1724,10 @@ static int tdx_sept_zap_private_spte(struct kvm *kvm, gfn_t gfn, > err = tdh_mem_range_block(&kvm_tdx->td, gpa, tdx_level, &entry, &level_state); > tdx_no_vcpus_enter_stop(kvm); > } > - if (tdx_is_sept_zap_err_due_to_premap(kvm_tdx, err, entry, level) && > - !KVM_BUG_ON(!atomic64_read(&kvm_tdx->nr_premapped), kvm)) { > + if (tdx_is_sept_zap_err_due_to_premap(kvm_tdx, err, entry, level)) { > + if (KVM_BUG_ON(!atomic64_read(&kvm_tdx->nr_premapped), kvm)) > + return -EIO; > + > atomic64_dec(&kvm_tdx->nr_premapped); > return 0; > }