From nobody Sun Feb 8 23:34:57 2026 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 46459285056 for ; Fri, 17 Oct 2025 00:33:12 +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=1760661194; cv=none; b=bFN4VgGfMVuw+qjxLpswYVpOGKVSi1Fre0uummcCTv96kMN/Kvz3hYQFoUgLYkwNmDIp0qHcfSpagwTaqGX68EYDi+m10nHSnciVuQ4hIwhOk5Bl300vld14GnsO4ak4WgfqJd+oBRQZeWRDYcIXJzBYIYdKkhsiaZVOPpUmPzw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760661194; c=relaxed/simple; bh=g9XE/XmOjyDDyTFp1eZETSR7kpDfFGyQ7oUmnFxVe5U=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=i8OcC2+YvrFCuOC572sIvDy1CIW4RwpLUzqiyHfxX5hHizYdGZ9rF5mFm9Dl+R5DzEjt2fOFrZEtu/nv6yCyzdu5e2dvpKhVpUOzfaL+kjufjbTASePOx2P4ucmOBrw8ZRlJmwdeSXe2CdAQIa8Fl9rwdzr4KbStJp3TzOXI49c= 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=tHr4DlwL; 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="tHr4DlwL" Received: by mail-pj1-f73.google.com with SMTP id 98e67ed59e1d1-32eb18b5500so2174536a91.2 for ; Thu, 16 Oct 2025 17:33:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1760661191; x=1761265991; darn=vger.kernel.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=tHr4DlwLH2QPutEBTZf00UhaF5tY5sOYkzcgcBKqjTfgauXffHWruC6gbzSIbuniMu vPMUZXgJXNjxjbGcr/I1cGBkADHOmK+mNrJpPh/W+DhoHrNaXHDYEhlU37dJX99uR2lT 3/hlePFECPUcEnJYHOr37i4sqxvBr0lrbQ8sVI0g72/9MfjG4ex43iWX9x4xgD2K+yFb wbbQB28BivmehBfYQ4qyGKX8HZ7r6jeFHWQ4xeZ6mjKehr7FyHDi0l7q8fX5dsbCBoy4 MbDZ0d1m7Xi+YZG8nDFjUzCc6LLAUGz0z9vd4lhFtvWU1hc7nGbK5n22I+Aieq+P5Pj9 X37w== 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=PMaYRASWX2c3DIvhFT8owLgPDNDM/AAkAjbhpn0zeYDQ0M9gJEP15VdOK88T0AaEtI ngXCp42apn66DEcsQC06wG2UKulPqlHxGs+IEmw4U9z1pfRHmxh57HY/jT1QBSt4am+W CVysUTlvemdUyUqk0s+rXU8cVZeiCpkYY/uV3BcTFMFvi+GbknA2OHSjZWVWyzzEjaoM O0zQIPB96bCcQLeDaClQpVegh6ZNvlDNqolzEs3WSzG0VBVJXAbVryZSy76W2oEhP/iv sNLrz2Wg4VBsxx0KOKOEvXPKsxe/f/Sdy4sroUkAmXsGzOMexeLPo4U+mwWlO62JQczt kj7A== X-Forwarded-Encrypted: i=1; AJvYcCVIRoPPfYrOIQuP3+/jHTkP5E3BqCIVDw4JZYKBD047bEfeEbfOJnPUTrhFV+CsiB/YYz8q678OMii+pjc=@vger.kernel.org X-Gm-Message-State: AOJu0Yw/G6yUp1FJZAOJvlm/r5VolmFHezIBazxd1sAz75IaW43ioDGA 0ttI4gbi7WHHsGIFIHw5JGZvik9E2ow1fWINMD6B3UG7+6c36RXJPCjlyvBQKTyPipQvImgHjYx J2hoY3A== 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) Reply-To: Sean Christopherson Date: Thu, 16 Oct 2025 17:32:31 -0700 In-Reply-To: <20251017003244.186495-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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-Transfer-Encoding: quoted-printable 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 Signed-off-by: Sean Christopherson Reviewed-by: Binbin Wu Reviewed-by: Kai Huang --- 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 g= fn, return 0; } =20 -/* - * KVM_TDX_INIT_MEM_REGION calls kvm_gmem_populate() to map guest pages; t= he - * 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 th= at - * 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 =3D 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 *kv= m, gfn_t gfn, return -EIO; =20 /* - * 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 =3D=3D TD_STATE_RUNNABLE)) - return tdx_mem_page_aug(kvm, gfn, level, pfn); =20 - 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 !=3D 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); } =20 static int tdx_sept_link_private_spt(struct kvm *kvm, gfn_t gfn, --=20 2.51.0.858.gf9c4a03a3a-goog