From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=209.85.216.72 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792807410; b=BGzykWJEc8yDmq1jittjIStH5zH1umstNVzgyrEHwX5id5IevhRx4+IsZmfgnPNa/iCb AIkyDcNrU6ucC4yCG4fbK6WnllfITo48da43gAXumN2QaKR4KlMhBBdO8ppIBlJyCpeQq IeF5EeIkiTV53dVzdROaijiwdASmCIE/lHlhWQIv/OcAnoHup8Ah7yQQT7bzRKx0V6wCJ SYY6YcJcv47YEXYbm1Q5q1zuXSLYGYeEoAE4fKY58vb8+rD71wN2gjUwDgNFkMiK13izR JugY3fuQFkRlmzUaOoFLKU7hMRt6CeEkNaxfcZu+xNcdyFRfPio39OHF6x1v157fRmg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792807410; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Received:Date:In-Reply-To: Mime-Version:References:Message-ID:Subject:From:To:Cc:Content-Type; bh=jNxeypu/UiKv86Z24ODkNybt5lTKhyqeVQWmn/P5E/Y=; b=lW7E/sFpn8FHu8R+ywGiDIPZLFsxM+ORyAADS2KSZ8vXEhvyLzJtkINjFv2Gu/z1LBJU a6szjViQa87/8z3Y2WOKmQavLG4zY+KIMwuxQ36HKfbdngMyhMjFkpbD09o05Zqoj+Yug sTmif06ORzSmQXQCYv3HSiB3ElmrPSijb/yWow4NgEwsX+X+SQneWEfOyUoh4dUPKpJNv IWVhF5/SNs8kWc6YlfBMNMHeCqwGKSR8F17JFOKDL7satsRUJqenDvfsEH87BRFuvl8Cj rAvHwRv/b3OODXikeQ1SrXUhNMpg+mZTzfuYrvN7aoq3V3EiMhrTZ8wRNUtHtg5IRHw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20251104 header.b="JTnK/Twk"; arc=none smtp.remote-ip=209.85.216.72 Received: from mail-pj1-f72.google.com (mail-pj1-f72.google.com [209.85.216.72]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 89C6B606A31A for ; Sat, 24 Oct 2026 02:03:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 89C6B606A31A 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, unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20251104 header.b=JTnK/Twk Received: by mail-pj1-f72.google.com with SMTP id 98e67ed59e1d1-3adf71ee6a5so94864a91.2 for ; Fri, 23 Oct 2026 19:03:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1792807409; x=1793412209; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=jNxeypu/UiKv86Z24ODkNybt5lTKhyqeVQWmn/P5E/Y=; b=JTnK/TwkMcpKjowTRm8Bj3UffAyiFW5NWIMJchCcd3KE9O1wn1UF5MUBQN5NVgFam2 IjEy8EDkgVmSG8hcXAACea8b9ysnom5zg89hvfeAhXJ5SPyEeqvvlyAs4pCG38XunYy2 rJZbdpxw5R64duX7wDGXQI7auzJFXD/5JkNWtpTM2cdN0zYCFkb9T7g7zZMBb5vJTVA1 VnToql/FQW5kI+SpyAOcNVR4srRpmSsu2Bh9RrZaLvcxrMYufhJT+xnz36SgSM7n9QsM nrzxYyZvW+5nF29MLihQ8Mxv++E5vvYtkD2fQ/8mLVLWca1L7l6uZCS+bKaHY5ya0lDw XVoQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1792807409; x=1793412209; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=jNxeypu/UiKv86Z24ODkNybt5lTKhyqeVQWmn/P5E/Y=; b=fxThczZIOJP9MqFQnfoyDsobU4Amx9+VM6ZIcj0OYiChANy9DrWwSYHqAFGH+KA/KG jzuWLGGUehB+q2rKPzXQTiS14oht1J+mISeBV8d/9neO26N/257O/TI8jfk+IepSHhT5 qT6t77rJv+nHck9l48Q/hznR7Pdna8PvKi/+1xfi9dyjH8S8IUo6joC05nOyw6ZbbcSV k5gFPbiIQXbL67gpjoDQ6Qm1UOPlsmBoi6kA9MJR976lekBjSHVvbh23Qa9nzc6X2wCa hwxXeWHaZTkvRx3x2neJYd0kcq8O0FKTqdaCjdG8iBAlOW4Vp5AELFw3rTgTlYMwjbNt MEBg== X-Forwarded-Encrypted: i=1; AKwUvByevxz0JUQ2bt+iIwmFBolR4Bl4Vp3taDLHihARoW2kysKIPsgD2AXvM3TqkIiGkUvWjpg=@vger.kernel.org X-Gm-Message-State: AFq9FYKGD3sxXuD3bBgk3/+vWNd5J3jMVbx+4tV2IgrBIfO1l6p/w1Kh 8W78Ay9w9A3t7NXkE9Kfrf9bTVBMWYFWeCwSc8ZLtj2b6YXGXvTMVbNuUPPQ8oCmF1XOjLufwhj /0jp/sQ== X-Received: from pgmr20.prod.google.com ([2002:a63:2054:0:b0:cd8:bb5c:4aef]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:3846:b0:3ac:945c:7f69 with SMTP id 98e67ed59e1d1-3adeb162362mr786457a91.66.1792807408684; Fri, 23 Oct 2026 19:03:28 -0700 (PDT) Date: Fri, 23 Oct 2026 19:03:27 -0700 In-Reply-To: <4e1d5d94-9956-4cc1-af5f-1311461ab233@linux.intel.com> X-Mailing-List: kvm@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list Mime-Version: 1.0 References: <20261022210134.612848-1-seanjc@google.com> <20261022210134.612848-3-seanjc@google.com> <4e1d5d94-9956-4cc1-af5f-1311461ab233@linux.intel.com> Message-ID: Subject: Re: [PATCH v2 2/3] KVM: TDX: Set SIGNIFCANT_INDEX flag as appropriate when filling CPUID entries From: Sean Christopherson To: Binbin Wu Cc: Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Kiryl Shutsemau , Rick Edgecombe , "H. Peter Anvin" , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-coco@lists.linux.dev, Changyuan Lyu , Sashiko Content-Type: text/plain; charset="us-ascii" On Fri, Oct 23, 2026, Binbin Wu wrote: > On 10/23/2026 5:01 AM, Sean Christopherson wrote: > > diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c > > index 271c2f94b8dd..37d088f6f7a8 100644 > > --- a/arch/x86/kvm/vmx/tdx.c > > +++ b/arch/x86/kvm/vmx/tdx.c > > @@ -2,6 +2,7 @@ > > #include > > #include > > #include > > +#include > > #include > > #include > > #include > > @@ -163,12 +164,23 @@ static void td_init_cpuid_entry2(struct kvm_cpuid_entry2 *entry, unsigned char i > > > > entry->function = (u32)td_conf->cpuid_config_leaves[idx]; > > entry->index = td_conf->cpuid_config_leaves[idx] >> 32; > > + entry->flags = 0; > > entry->eax = (u32)td_conf->cpuid_config_values[idx][0]; > > entry->ebx = td_conf->cpuid_config_values[idx][0] >> 32; > > entry->ecx = (u32)td_conf->cpuid_config_values[idx][1]; > > entry->edx = td_conf->cpuid_config_values[idx][1] >> 32; > > > > - if (entry->index == KVM_TDX_CPUID_NO_SUBLEAF) > > + WARN_ON_ONCE(cpuid_function_is_indexed(entry->function) != > > + (entry->index != KVM_TDX_CPUID_NO_SUBLEAF)); > > + > > + /* > > + * Explicitly zero the index when it's not significant, even though it > > + * _should_ be meaningless. Userspace relies on the index being zero > > + * (the ABI was inherited from KVM_GET_SUPPORTED_CPUID). > > + */ > > + if (cpuid_function_is_indexed(entry->function)) > > If the information about whether the entry is indexed mismatched, i.e. the > warning above fired, should we use the information from the TDX module as the > standard? IMO, no. All of this information is available at module load. If we want to harden KVM (and we probably should), then we should apply these sanity checks (or equivalents) during tdx_hardware_setup() and disable TDX if any of them fail. Anything else is a hope and a prayer.