From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.17]) (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 97E61320A0F; Mon, 17 Nov 2025 08:53:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.17 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763369609; cv=none; b=CpWrnKNB+0hFqlAf8uDNMQErYnMl4cARkOA0WvSyCGqEj8NrnyD0Z6r2C2D2Kb0INCsmB+A2iHuB767hox6THRN46wiXt1Pdeuwg2EbJX+WM8YyONPmcf5mBjL94qEC9SURmWfH8jTQWYfUKzNWUIc8CMAD7wW14mi1lf+uMjDk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763369609; c=relaxed/simple; bh=AunLOyJgC5jZdtspWty73Gl8zbB+LD4+e4vJdXSs2Cc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=F0beFE3OlxawhuspmG+T5dexMjZOqKehKsO0seMwLVt6fagIdL3uAQ90Y31Nc47sj5lwBQAAHsEe9Tdz5eD3L/ndDnAPicJutResT/DiGmqcIsthbVcT1xMWFGE9SlZF1nowDz0lrdYxmAnQUB1oMh+Wgm2Z8fVfQIFtv0RoKSw= 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=EQZjklGL; arc=none smtp.client-ip=192.198.163.17 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="EQZjklGL" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1763369606; x=1794905606; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=AunLOyJgC5jZdtspWty73Gl8zbB+LD4+e4vJdXSs2Cc=; b=EQZjklGLk+j9j3Q/jDn5v+tTQVacHilZNDBk76dTzDgHqQPaTSHO+/4F fyjBIUtXT5/EfwSzQP1DNmgbKQavQGqt7gzkql/PpopLNvrxKoAM4ZF7o IJ+g814j3koYn1COXmxfZeyH7yGOTg9LQdSGxUlcgPzHwzYSNWRK55a4S whzIUXhjz31J/X0gxXI0FtqeYQjaqsRyfhNVGsOtv0ky+Ea98zVXNcSEC QCiIsdGPyb4MCXOa/x8EcW8etzEtxWTwSJIQ38DEY0EvRRtev8YA3iYDp JpJslHCqU70V6GrU4rEUgKiU8gKmcPI65sFsT6rMjing89U2KTgi7VchC w==; X-CSE-ConnectionGUID: haAbpKmmR7WpVb4TSfFrGw== X-CSE-MsgGUID: 0h1jkkGwSQmqOfLHqhEixA== X-IronPort-AV: E=McAfee;i="6800,10657,11615"; a="65264668" X-IronPort-AV: E=Sophos;i="6.19,311,1754982000"; d="scan'208";a="65264668" Received: from fmviesa006.fm.intel.com ([10.60.135.146]) by fmvoesa111.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Nov 2025 00:53:25 -0800 X-CSE-ConnectionGUID: oKmuX6bpQRaHZBBMKhKZig== X-CSE-MsgGUID: CRw9wYg1SgitB4ulQQEVgg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.19,311,1754982000"; d="scan'208";a="190190560" Received: from yinghaoj-desk.ccr.corp.intel.com (HELO [10.238.1.225]) ([10.238.1.225]) by fmviesa006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Nov 2025 00:53:20 -0800 Message-ID: <60da8b1c-07ea-47fe-9bfd-d87bde294e3e@linux.intel.com> Date: Mon, 17 Nov 2025 16:53:17 +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 09/23] KVM: x86/tdp_mmu: Add split_external_spt hook called during write mmu_lock To: Yan Zhao Cc: pbonzini@redhat.com, seanjc@google.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, x86@kernel.org, rick.p.edgecombe@intel.com, dave.hansen@intel.com, kas@kernel.org, tabba@google.com, ackerleytng@google.com, quic_eberman@quicinc.com, michael.roth@amd.com, david@redhat.com, vannapurve@google.com, vbabka@suse.cz, thomas.lendacky@amd.com, pgonda@google.com, zhiquan1.li@intel.com, fan.du@intel.com, jun.miao@intel.com, ira.weiny@intel.com, isaku.yamahata@intel.com, xiaoyao.li@intel.com, chao.p.peng@intel.com References: <20250807093950.4395-1-yan.y.zhao@intel.com> <20250807094320.4565-1-yan.y.zhao@intel.com> Content-Language: en-US From: Binbin Wu In-Reply-To: <20250807094320.4565-1-yan.y.zhao@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 8/7/2025 5:43 PM, Yan Zhao wrote: [...] > /** > * handle_removed_pt() - handle a page table removed from the TDP structure > * > @@ -765,12 +778,20 @@ static u64 tdp_mmu_set_spte(struct kvm *kvm, int as_id, tdp_ptep_t sptep, > handle_changed_spte(kvm, as_id, gfn, old_spte, new_spte, level, false); > > /* > - * Users that do non-atomic setting of PTEs don't operate on mirror > - * roots, so don't handle it and bug the VM if it's seen. > + * Propagate changes of SPTE to the external page table under write > + * mmu_lock. > + * Current valid transitions: > + * - present leaf to !present. > + * - present non-leaf to !present. Nit: Maybe add a small note to limit the scenario, such as "after releasing the HKID" or "during the TD teardown"? > + * - present leaf to present non-leaf (splitting) > */ > if (is_mirror_sptep(sptep)) { > - KVM_BUG_ON(is_shadow_present_pte(new_spte), kvm); > - remove_external_spte(kvm, gfn, old_spte, level); > + if (!is_shadow_present_pte(new_spte)) > + remove_external_spte(kvm, gfn, old_spte, level); > + else if (is_last_spte(old_spte, level) && !is_last_spte(new_spte, level)) > + split_external_spt(kvm, gfn, old_spte, new_spte, level); > + else > + KVM_BUG_ON(1, kvm); > } > > return old_spte;