From nobody Thu Oct 2 19:27:56 2025 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (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 C25352DC329 for ; Fri, 12 Sep 2025 23:24:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757719448; cv=none; b=dYDTt/DRJp73NjxBoxWaNovsdgnt53cB942ZpWhfVio2PecALsBFOupKqkKjEQKsUz6BbdvozbQiBNGTG4MdkeBlzTUPkuWUbQF2vyv/1FPMHMc820CmCGXrJVPriebOPgYvwJHpIUZp4hviElTVaAdL4gpVYOUELvQR/Wkjgrw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757719448; c=relaxed/simple; bh=MPZBvYn5dIhEZftsLXy+k1gliAtB05haepqZLfWlI+o=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=EjA1QptbgPLqy5vWhpHmaYnByRMuTKFaQFqxp8nyJFGmDDYW4w744lgN3fls9JaXPYq0fafgecn77xh+c1IXiA9IbbVPsgRLsjkdiEXcrwLVkacWWkOe14IcDOeWCXFNjS5lQhqVLLsyTJVwGZDgGgtYlGmu6jYyb+GXLdXQ69w= 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=bmp1dC+P; arc=none smtp.client-ip=209.85.216.74 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="bmp1dC+P" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-32deef33abdso1264980a91.3 for ; Fri, 12 Sep 2025 16:24:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1757719446; x=1758324246; 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=04uvHjxAqDu/hC/6pYykcUt3v/Ox1tG5Jh6i2BGlxXk=; b=bmp1dC+P+WNg5NtZp3TICmvJyu5leYSOWk2XEBrLvdRWnL8cArxcsC1VDDNPkBit2U dx7hDVO7GVJAed4HfnHCNJiTkFSM1fzcVt2yEAV+6H8+St8eaMb1nvkhfBwlCBBerac7 1kmvi6xHfxn1Q7hT5Xp18SDaSrgAdGPIPhPmgOvYq5fdMnpnDR3MUbTcWcp0rca9YRnm dJ6ZLy8JB8gt8impI+odA8d5CiuGsLGF2wl+S91c6Ag3upWYxSkNJg08TxhZj70FNTe7 i1vCPeyXeFiasaf2v69FgVeovfM0Y+biLJXKGtLKn34uBBpVypoVnVsp7OISOzyhdQgw T5VQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1757719446; x=1758324246; 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=04uvHjxAqDu/hC/6pYykcUt3v/Ox1tG5Jh6i2BGlxXk=; b=Kfl15e1ygSpskj2/frI0ETnIAq4/Yhxu7ahTAUbDVjbiFapfsMz1NPOkeDTS+E/KwX AnQ1KQ7g0fz1VfkNG9Gq6tIUG61lj0gdUnek1Bt2OH49XKQyjdaibPfsCmbZlsqmHPvk sq7V2T1SJNo7BfTTdQ9tdL3lxjt0zim+dG0KaC1eEeK4sJe2dy6elAYgpDzJVkrMZtOx z7zCEvkfdZbChTAraAtsYXH+YxWbIiwIvzfCsfLoP38WqHF2eDLD2gRQnfr/XRSwG92f 3bnNRDIo2bvXXRjmKfzf7Uvr9LFdO2ZnR9HaiywdupqnN077R2g/qAGWEbaW79Yva8lZ 0CaQ== X-Forwarded-Encrypted: i=1; AJvYcCUSyyKURl+mSRKHxflbhgy4bcFaIw0AvCWOdVT5N4Yil6/2OMiO+jtoidHRfk3i9uKhtdMJCLIesk38I74=@vger.kernel.org X-Gm-Message-State: AOJu0YxuhRKDwSG33Ji280DgXnE1Q6VUhoyweRHxDxdswfjMVofDVE8c ddJpV5AFSoL1NUEvusG0M8obCB+kzO+X5xcitgKKGn+wadFF1ykiVCe5vQQSFJpICdzTp0naHZz U3f2LmA== X-Google-Smtp-Source: AGHT+IEzQt6auq3+8YRv+SuIK8SxREofv/BnooxdLXGs0d7AyO5RocHDIBzoU5UiRRPS8qyHEi9SECBARug= X-Received: from pjtu6.prod.google.com ([2002:a17:90a:c886:b0:32d:a0b1:2b14]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90a:fc4d:b0:329:e729:b2a1 with SMTP id 98e67ed59e1d1-32de4fa1c8bmr5081666a91.35.1757719446146; Fri, 12 Sep 2025 16:24:06 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 12 Sep 2025 16:23:01 -0700 In-Reply-To: <20250912232319.429659-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250912232319.429659-1-seanjc@google.com> X-Mailer: git-send-email 2.51.0.384.g4c02a37b29-goog Message-ID: <20250912232319.429659-24-seanjc@google.com> Subject: [PATCH v15 23/41] KVM: nVMX: Add consistency checks for CET states From: Sean Christopherson To: Paolo Bonzini , Sean Christopherson Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Tom Lendacky , Mathias Krause , John Allen , Rick Edgecombe , Chao Gao , Maxim Levitsky , Xiaoyao Li , Zhang Yi Z Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Chao Gao Introduce consistency checks for CET states during nested VM-entry. A VMCS contains both guest and host CET states, each comprising the IA32_S_CET MSR, SSP, and IA32_INTERRUPT_SSP_TABLE_ADDR MSR. Various checks are applied to CET states during VM-entry as documented in SDM Vol3 Chapter "VM ENTRIES". Implement all these checks during nested VM-entry to emulate the architectural behavior. In summary, there are three kinds of checks on guest/host CET states during VM-entry: A. Checks applied to both guest states and host states: * The IA32_S_CET field must not set any reserved bits; bits 10 (SUPPRESS) and 11 (TRACKER) cannot both be set. * SSP should not have bits 1:0 set. * The IA32_INTERRUPT_SSP_TABLE_ADDR field must be canonical. B. Checks applied to host states only * IA32_S_CET MSR and SSP must be canonical if the CPU enters 64-bit mode after VM-exit. Otherwise, IA32_S_CET and SSP must have their higher 32 bits cleared. C. Checks applied to guest states only: * IA32_S_CET MSR and SSP are not required to be canonical (i.e., 63:N-1 are identical, where N is the CPU's maximum linear-address width). But, bits 63:N of SSP must be identical. Tested-by: Mathias Krause Tested-by: John Allen Tested-by: Rick Edgecombe Signed-off-by: Chao Gao Signed-off-by: Sean Christopherson --- arch/x86/kvm/vmx/nested.c | 47 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index a73f38d7eea1..edb3b877a0f6 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -3101,6 +3101,17 @@ static bool is_l1_noncanonical_address_on_vmexit(u64= la, struct vmcs12 *vmcs12) return !__is_canonical_address(la, l1_address_bits_on_exit); } =20 +static bool is_valid_cet_state(struct kvm_vcpu *vcpu, u64 s_cet, u64 ssp, = u64 ssp_tbl) +{ + if (!kvm_is_valid_u_s_cet(vcpu, s_cet) || !IS_ALIGNED(ssp, 4)) + return false; + + if (is_noncanonical_msr_address(ssp_tbl, vcpu)) + return false; + + return true; +} + static int nested_vmx_check_host_state(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12) { @@ -3170,6 +3181,26 @@ static int nested_vmx_check_host_state(struct kvm_vc= pu *vcpu, return -EINVAL; } =20 + if (vmcs12->vm_exit_controls & VM_EXIT_LOAD_CET_STATE) { + if (CC(!is_valid_cet_state(vcpu, vmcs12->host_s_cet, vmcs12->host_ssp, + vmcs12->host_ssp_tbl))) + return -EINVAL; + + /* + * IA32_S_CET and SSP must be canonical if the host will + * enter 64-bit mode after VM-exit; otherwise, higher + * 32-bits must be all 0s. + */ + if (ia32e) { + if (CC(is_noncanonical_msr_address(vmcs12->host_s_cet, vcpu)) || + CC(is_noncanonical_msr_address(vmcs12->host_ssp, vcpu))) + return -EINVAL; + } else { + if (CC(vmcs12->host_s_cet >> 32) || CC(vmcs12->host_ssp >> 32)) + return -EINVAL; + } + } + return 0; } =20 @@ -3280,6 +3311,22 @@ static int nested_vmx_check_guest_state(struct kvm_v= cpu *vcpu, CC((vmcs12->guest_bndcfgs & MSR_IA32_BNDCFGS_RSVD)))) return -EINVAL; =20 + if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_CET_STATE) { + if (CC(!is_valid_cet_state(vcpu, vmcs12->guest_s_cet, vmcs12->guest_ssp, + vmcs12->guest_ssp_tbl))) + return -EINVAL; + + /* + * Guest SSP must have 63:N bits identical, rather than + * be canonical (i.e., 63:N-1 bits identical), where N is + * the CPU's maximum linear-address width. Similar to + * is_noncanonical_msr_address(), use the host's + * linear-address width. + */ + if (CC(!__is_canonical_address(vmcs12->guest_ssp, max_host_virt_addr_bit= s() + 1))) + return -EINVAL; + } + if (nested_check_guest_non_reg_state(vmcs12)) return -EINVAL; =20 --=20 2.51.0.384.g4c02a37b29-goog