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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 DC805CCD1A3 for ; Fri, 17 Oct 2025 00:35:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Reply-To:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:Cc:To: From:Subject:Message-ID:References:Mime-Version:In-Reply-To:Date: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=tdDvnnMBi79Itp61RxW2nV56QIHnitcyrtTO64NTOt8=; b=vsn/OTdPfszTvwn8/8sE96sY0Y q7AWCVh+h1iiiRwAcLFPkNvrdTmyHhR1XHOvZReyaN0/ealsnW+fRH8jTsoHaaWnLCicurkPz9SPc Zqo6XnhMqqJ8I3IzkLS4qAaw35Nw7+hf6J/rjlH863bNAdTzHFgxajoQDRFV6qJ2JMI9fotekRuq7 HDbhnPBzHN0PRrzSZa5no7f0TKnN4NFK2gktuHyzhyJqzkPW+FgsCiVKpRMtT28nUwNs3O4wSf/Vg 1qJX9kA05FKCLOF51b7r1jqDckWdltOhOb0VZ+825E4TgoytZHq48C/HKS08mGcXfhGEfVmpCgvf6 2DtX19ZA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1v9YQu-00000006FpK-3UBp; Fri, 17 Oct 2025 00:35:00 +0000 Received: from desiato.infradead.org ([2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1v9YPq-00000006Dw6-3wVC for linux-arm-kernel@bombadil.infradead.org; Fri, 17 Oct 2025 00:33:56 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Type:Cc:To:From:Subject: Message-ID:References:Mime-Version:In-Reply-To:Date:Reply-To:Sender: Content-Transfer-Encoding:Content-ID:Content-Description; bh=tdDvnnMBi79Itp61RxW2nV56QIHnitcyrtTO64NTOt8=; b=KtZOCGqyfLp9RvrpsS4dn7AY8H LpWueXQfwrEiUnKyaYNXAISJprC75pkBI7ZmcwwPYLQh/M2Y8qum8I1Y4vcC9Zoifgeom2vim+SDz k75rUXMuRMlpXCdP96Rcst8nuFmrxVl08TED0peYJLHPjwkd9+tnCxYbfGBdcqVXuYwAKKU7eerCB 8/ZR79AIuaa/cVsBy9Bjm0+PY7Zt4cZiHbsdsghlwhrtzC76LasZaKfQLmLYHQ+LWHaOwBgV7xVMd Q7wphwCyjg/ofXBulqnmHi4eFTiR8oYT2nJsVjJEf3dqrr3U0p0R8WAa20gQWcpYkJVGJ87lpPxQj sc4Hqxxw==; Received: from mail-pj1-x1049.google.com ([2607:f8b0:4864:20::1049]) by desiato.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1v9YPH-000000078Hb-1Gza for linux-arm-kernel@lists.infradead.org; Fri, 17 Oct 2025 00:33:41 +0000 Received: by mail-pj1-x1049.google.com with SMTP id 98e67ed59e1d1-32eb18b5500so2174533a91.2 for ; Thu, 16 Oct 2025 17:33:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1760661191; x=1761265991; darn=lists.infradead.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=tdDvnnMBi79Itp61RxW2nV56QIHnitcyrtTO64NTOt8=; b=ga+9WLH5HG7ItnAGHXcmpHcFVOOFb99e00cmVi6aGZHHZ3x/3dqdZQdY96pVAdsVyH vlTZNc++kLVjoeeNAmG7+dMCsmZDwe/D0VgVsQNERFS9/+Wl7/0OJ2w3iKAtryBIBaCa VKYuxhyTCoWmkXC8t9hW04fgs1wOosNuhdmy7YQJqnQseYQspZZB+42nYim3nCYqEua8 xKxhNtJVWT73D2kSFzkjfpMJuUUowvq2//1ReCJic/yRo6U/oEr/7YrFPPaD3t6D/x27 lMbZAPTOOjTTiISnY84Df9T5m61H0feEqafZb2HSgEM2mRUKHo8+lhzBH6ycuk1PS4aG AOkg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1760661191; x=1761265991; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=tdDvnnMBi79Itp61RxW2nV56QIHnitcyrtTO64NTOt8=; b=EsDQ6cPpl5BdfB8GTMGqNtHrlLKrW1x9Zstlmgg7mO31SaQRSTexPhEITF8+mk3Gb4 RWvu5l6gMtI5qKBZxVS6alhzKSKA3MPdabHRzMYb5BmImAUQYADffW0g2QTS86xKw9ls AEnxB4Tu6Ulopjp/dWfo84axkejgWXq09FnHWhxeUcqxEaH9wqLcFMPIhDQd1PhKT6iO X6erbFZQ41TKZcI7ruK5gSvTkQ6IdGnuve3CnBrgJvYzY9OEnObAsO67zPQPViDjY7G0 duW4trdzMcLesw/R2E/CfI9cPuCoBnaKrR/Au8aIR1Q6xnAmsjk1M25jiPJLjyHR8OI7 zMiA== X-Gm-Message-State: AOJu0YwTvvvHAdu30G5D1laIGPO/GK4Dz9WZVa+MblEtSC8Pq4zncG1N Rv2jVrluaUk4+w02Uid4VQD08xGVxxH/nR8RukmyArCv8n55sQOfLxpccuXWZstZElSC1MxlwpB +bsgWFg== X-Google-Smtp-Source: AGHT+IFjbvhuJBf5rM9mXEGAaRcwet/6S3ph7hsVNQrCN7ddhA3ec/NJFjzeh48C6n1kB16/mom5cp7HTgE= X-Received: from pjso17.prod.google.com ([2002:a17:90a:c091:b0:32e:3830:65f2]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:1dc4:b0:330:6f13:53fc with SMTP id 98e67ed59e1d1-33bcf8f870bmr1842078a91.27.1760661191207; Thu, 16 Oct 2025 17:33:11 -0700 (PDT) Date: Thu, 16 Oct 2025 17:32:31 -0700 In-Reply-To: <20251017003244.186495-1-seanjc@google.com> Mime-Version: 1.0 References: <20251017003244.186495-1-seanjc@google.com> X-Mailer: git-send-email 2.51.0.858.gf9c4a03a3a-goog Message-ID: <20251017003244.186495-14-seanjc@google.com> Subject: [PATCH v3 13/25] KVM: TDX: Fold tdx_mem_page_record_premap_cnt() into its sole caller From: Sean Christopherson To: Marc Zyngier , Oliver Upton , Tianrui Zhao , Bibo Mao , Huacai Chen , Madhavan Srinivasan , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Sean Christopherson , Paolo Bonzini , "Kirill A. Shutemov" Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvm@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, x86@kernel.org, linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, Ira Weiny , Kai Huang , Michael Roth , Yan Zhao , Vishal Annapurve , Rick Edgecombe , Ackerley Tng , Binbin Wu Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251017_013338_581425_483A0B1C X-CRM114-Status: GOOD ( 18.91 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Sean Christopherson Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Fold tdx_mem_page_record_premap_cnt() into tdx_sept_set_private_spte() as providing a one-off helper for effectively three lines of code is at best a wash, and splitting the code makes the comment for smp_rmb() _extremely_ confusing as the comment talks about reading kvm->arch.pre_fault_allowed before kvm_tdx->state, but the immediately visible code does the exact opposite. Opportunistically rewrite the comments to more explicitly explain who is checking what, as well as _why_ the ordering matters. No functional change intended. Reviewed-by: Rick Edgecombe Signed-off-by: Sean Christopherson --- arch/x86/kvm/vmx/tdx.c | 49 ++++++++++++++++++------------------------ 1 file changed, 21 insertions(+), 28 deletions(-) diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c index 6c0adc1b3bd5..c37591730cc5 100644 --- a/arch/x86/kvm/vmx/tdx.c +++ b/arch/x86/kvm/vmx/tdx.c @@ -1605,29 +1605,6 @@ static int tdx_mem_page_aug(struct kvm *kvm, gfn_t gfn, return 0; } -/* - * KVM_TDX_INIT_MEM_REGION calls kvm_gmem_populate() to map guest pages; the - * callback tdx_gmem_post_populate() then maps pages into private memory. - * through the a seamcall TDH.MEM.PAGE.ADD(). The SEAMCALL also requires the - * private EPT structures for the page to have been built before, which is - * done via kvm_tdp_map_page(). nr_premapped counts the number of pages that - * were added to the EPT structures but not added with TDH.MEM.PAGE.ADD(). - * The counter has to be zero on KVM_TDX_FINALIZE_VM, to ensure that there - * are no half-initialized shared EPT pages. - */ -static int tdx_mem_page_record_premap_cnt(struct kvm *kvm, gfn_t gfn, - enum pg_level level, kvm_pfn_t pfn) -{ - struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm); - - if (KVM_BUG_ON(kvm->arch.pre_fault_allowed, kvm)) - return -EIO; - - /* nr_premapped will be decreased when tdh_mem_page_add() is called. */ - atomic64_inc(&kvm_tdx->nr_premapped); - return 0; -} - static int tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn, enum pg_level level, kvm_pfn_t pfn) { @@ -1638,14 +1615,30 @@ static int tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn, return -EIO; /* - * Read 'pre_fault_allowed' before 'kvm_tdx->state'; see matching - * barrier in tdx_td_finalize(). + * Ensure pre_fault_allowed is read by kvm_arch_vcpu_pre_fault_memory() + * before kvm_tdx->state. Userspace must not be allowed to pre-fault + * arbitrary memory until the initial memory image is finalized. Pairs + * with the smp_wmb() in tdx_td_finalize(). */ smp_rmb(); - if (likely(kvm_tdx->state == TD_STATE_RUNNABLE)) - return tdx_mem_page_aug(kvm, gfn, level, pfn); - return tdx_mem_page_record_premap_cnt(kvm, gfn, level, pfn); + /* + * If the TD isn't finalized/runnable, then userspace is initializing + * the VM image via KVM_TDX_INIT_MEM_REGION. Increment the number of + * pages that need to be mapped and initialized via TDH.MEM.PAGE.ADD. + * KVM_TDX_FINALIZE_VM checks the counter to ensure all mapped pages + * have been added to the image, to prevent running the TD with a + * valid mapping in the mirror EPT, but not in the S-EPT. + */ + if (unlikely(kvm_tdx->state != TD_STATE_RUNNABLE)) { + if (KVM_BUG_ON(kvm->arch.pre_fault_allowed, kvm)) + return -EIO; + + atomic64_inc(&kvm_tdx->nr_premapped); + return 0; + } + + return tdx_mem_page_aug(kvm, gfn, level, pfn); } static int tdx_sept_link_private_spt(struct kvm *kvm, gfn_t gfn, -- 2.51.0.858.gf9c4a03a3a-goog