From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f73.google.com (mail-pj1-f73.google.com [209.85.216.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 27E8B384B9C for ; Thu, 30 Oct 2025 20:10:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.73 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761855039; cv=none; b=jkHRGEalifSj6Uguv+wfu3tP1q/6rl8UINijQElxWEJUTmHIhVUzJ+69Xl3pIfWRvS28uWukgRA3ULYIQgCXfqRTcwWWm2vnCIWVwG7a5vcIJQpVml9E3P4LtkFg8mjJb2ZnZxZ/APViGm6Vhdt9+8LuutFCd4b+Ra6jSfWddRQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761855039; c=relaxed/simple; bh=/ZmwuSI1/TsBi/hdaMNzxUBuHFwJZlKVkIuQ67ClOls=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=jWQMa6CRPVFayE8paiZeuobHM3IVuefff8uq+YiBmi+mbRjjamcCnD1B8wcpEK66+qvg01jdIy7nXgO0FGAPvONOUgFwlGMQAkmjsybERs5OIf36BBsln3HdJKyGa76idRFoKesUIMdLzjxEO6HHdZAojD1EN8g0aC33PLJscL4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=bBKkNxF4; arc=none smtp.client-ip=209.85.216.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="bBKkNxF4" Received: by mail-pj1-f73.google.com with SMTP id 98e67ed59e1d1-32edda89a37so1493111a91.1 for ; Thu, 30 Oct 2025 13:10:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1761855037; x=1762459837; darn=lists.linux.dev; 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=/Z7Z4VCKxvbeclMBJpiAZWPr8rGnQCyDletBZbiKOLg=; b=bBKkNxF4tjobOUK1m44200L9WaDzD9uJIL/jhl3jvoUZ6SAyWoFHMQvGrMzJqCDX+k Sq+RS/3Tcgh44XekuA3wrm1FMu5DFgFxSorUn/TO6T8zx0bvCBvfEZ+Vb6+mXM4k5hQr j5yQX7lmNVvaiwbuCfs4wmjwmE2rudkPMHn8CHpNvEYQKyrxr/1s5li6NpeOYwoQuAea K+xjd+tEhudQgAvfTasAHRmZc6fTjDJSqRkGepNf9gmh3OO+fLyJoCynCHxqFzz57HzI GT/0gVTZt7nbduxDs56Jd7G5GJ3rfNo548AJaoihn0Bb8C4vCVlNrntKMBE2EGMgmsMM GaAQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1761855037; x=1762459837; 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=/Z7Z4VCKxvbeclMBJpiAZWPr8rGnQCyDletBZbiKOLg=; b=G+dw4e+yA0sM8edbJsLJfqc+eKBzkj5fqLTGjoJNFD2Zeu4CqhgDEzQjxf9nf49eR2 BLLSmHFTJckyoFawQzyfQUYMAbz+WyfUdoRhlvMvlCmbTYszkNHMHVYVVXqXKR/HZOaw s1Fv6iqvd8e0vPoY1P6hYlewO9vYsr2Dbd5SmlFL/ERcTR2/X31pbNzWsv6WIGgHmNou fg5DqPDqL+HrtQAqDCpPsaWQO1KCTT4pdqp0P9FnFISxCn4Sagl3Q6Dj0ZHFt9a1SKVd 3O1wY+cjkPR2p8ZQn0j3ne7K1+dJFEVsX9zipBhlJ9RAXEuevjEpotVhN7pemONBTSqC LhtA== X-Forwarded-Encrypted: i=1; AJvYcCXY3iZ4bLTObXjQ54CO4rk76vEXoecVjz/gaM/ZU5bZyJ3bDYdVX5XtNCWUJIZ2WMjpS+/QzQU=@lists.linux.dev X-Gm-Message-State: AOJu0Yx3CKgzwH0Ezraqnkhhlmphjb+pRQWpnBD2Tb7IZgAdomM+80/X VDQADZSj1NqUwycXG4sJclqv3tU/MSzR64ayLDqiOeBHhjF2d4T/tcMhC9ZJYXc1NDCyhpAcajS Z4a9G6Q== X-Google-Smtp-Source: AGHT+IGuQ9tseR+UxrPGQmatIE4dzuj8mufA6J/LivL787A5dSoSjpBpOEZB47eEhvzGXFTpSKaWylv+I0w= X-Received: from pjqx5.prod.google.com ([2002:a17:90a:b005:b0:32d:dbd4:5cf3]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:3141:b0:339:a323:30fe with SMTP id 98e67ed59e1d1-34082fdc1a5mr1313871a91.14.1761855037257; Thu, 30 Oct 2025 13:10:37 -0700 (PDT) Reply-To: Sean Christopherson Date: Thu, 30 Oct 2025 13:09:38 -0700 In-Reply-To: <20251030200951.3402865-1-seanjc@google.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251030200951.3402865-1-seanjc@google.com> X-Mailer: git-send-email 2.51.1.930.gacf6e81ea2-goog Message-ID: <20251030200951.3402865-16-seanjc@google.com> Subject: [PATCH v4 15/28] 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 , Binbin Wu , Michael Roth , Yan Zhao , Vishal Annapurve , Rick Edgecombe , Ackerley Tng Content-Type: text/plain; charset="UTF-8" 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 Reviewed-by: Binbin Wu Reviewed-by: Kai Huang 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 99db19e02cf1..a30471c972ba 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, u64 mirror_spte) { @@ -1642,14 +1619,30 @@ static int tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn, (mirror_spte & VMX_EPT_RWX_MASK) != VMX_EPT_RWX_MASK); /* - * 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 pre-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, -- 2.51.1.930.gacf6e81ea2-goog