From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f201.google.com (mail-pl1-f201.google.com [209.85.214.201]) (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 EFF6E3E717B for ; Fri, 29 May 2026 22:22:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780093379; cv=none; b=L6TrTYyYpfLuL4SvjtjIysdL/D3eUDPIA+4PACTM2lFhSvmG9tv/tVIUXQdQvrdu4BYFyqE8upHTAyxJt/zbIb95YZF9QK/oUSYddlGgw3S/bQfpvYJuqYJN/JDtDpbIbLYeTzcD6EJVt7SEiKzZNm3nPN/cy0QPYf/tQMd0Mqs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780093379; c=relaxed/simple; bh=O6sCALoH9EmCcgisAiG+6wKleryQICAogURF+M73YgA=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=mUgZIICjm7w3MZYyiVeXupz/+Oj5g0dpH9fwiZrrGrIPStMQ0AJJ0J7o4A7+9ZgSjULtF5JHZK9E+rXX5MIdYt0Y642VAhieoSL4Kf/Y/nUk+JKF2KKcd5j3GlnuTVfsg/M4Rgdgo+VDPd5GigEKl93CvrivKZFc5UB6VUcFdBM= 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=cOh/ReEf; arc=none smtp.client-ip=209.85.214.201 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="cOh/ReEf" Received: by mail-pl1-f201.google.com with SMTP id d9443c01a7336-2bd6aeb3637so318815975ad.2 for ; Fri, 29 May 2026 15:22:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1780093377; x=1780698177; 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=YESkxGyiczq5Z97XVWhBBl+heltge9f5w5uhIKBe0e8=; b=cOh/ReEfkJwKeVn8l2OTNCWPqm43yFH4HPdtGNZkT3jiXK5SFU+fHT3vSV4tpZecz1 TDgy3s53T2VPP5kBx/UR87YcYkTXEMw6wR29GaBgHgBHe76fMkINhnTtzx86EYmvFeZi FreVb0k7TDYr7MaVfz1iChqH9SbeVjM0TTIUX5kFSXN7ULgSmj7HCKa7U/miCzJPGjkm acfnI7Q79Ijdm8f7X3yWoz+auYYeo8DqnFzWrklMtkDVuaNZEsWNIHalAMZ4HP8pC8pg rmGiHvpeMFh58QJmIogotxanjH/oxQQ0hrS1avIFp3A7sooYNK6Qrog3I+cTGrRnHYX+ kegQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780093377; x=1780698177; 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=YESkxGyiczq5Z97XVWhBBl+heltge9f5w5uhIKBe0e8=; b=STQuHaPwxv13fluWRlizXMHzbPZa2pAoS8ALSA+r23ZgcquB6ZbMajBgllqsYa0Amc qrx4/WBJKkgyun3TT38X3Ql0PsBDxQi55g+1GtkBaOylO5WYaH9h1gUxKafF1EY/Bcg2 ZS9OA5K/IQHMYp7I8kkuqbHq6pBsV72ONMprK4e4G3hXmSqc443vM2F+TJmpoPd0bpqe EXovOg+nT5t4rZgX5NqFOtwPhtgiHaTnHfYiF4DvR31ZPBde2ergvwM2nh48QVYQvMyd ZHrxZv5+qqGpw9WaUO1s1JM9dMOLyG5iLmorneksgcN3e1l2FfmNUat4wBOSBwDj2idq OaLA== X-Forwarded-Encrypted: i=1; AFNElJ8z542PXluKaDf9EwvgVGJo22czol/TBUvhmJCzh2WEQ3CBcBMvBfBv9Oi/pk+R3oGQRoOjrkLxMoT3YtQ=@vger.kernel.org X-Gm-Message-State: AOJu0YyG0ITra2LUxZR5Jwilv9wepEC+lRCHNynUv6KW8cewVHxLfFYs rN3QwTB9nkvHjbcp8+sz2wsbo3jCx0H5MQkB1pvUdKrEh2mOKG87mATX0AGq+j0souvV1Zk4G88 4UJOm8A== X-Received: from plbkn8.prod.google.com ([2002:a17:903:788:b0:2bd:25ca:82e9]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:d4c4:b0:2bf:e42:2a94 with SMTP id d9443c01a7336-2bf368a4096mr19964205ad.38.1780093377142; Fri, 29 May 2026 15:22:57 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 29 May 2026 15:21:55 -0700 In-Reply-To: <20260529222223.870923-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260529222223.870923-1-seanjc@google.com> X-Mailer: git-send-email 2.54.0.823.g6e5bcc1fc9-goog Message-ID: <20260529222223.870923-13-seanjc@google.com> Subject: [PATCH v3 12/40] KVM: x86: Harden is_64_bit_hypercall() against bugs on 32-bit kernels From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini , Vitaly Kuznetsov , David Woodhouse , Paul Durrant Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Yosry Ahmed , Binbin Wu , David Woodhouse , Kai Huang Content-Type: text/plain; charset="UTF-8" Unconditionally return %false for is_64_bit_hypercall() on 32-bit kernels to guard against incorrectly setting guest_state_protected, and because in a (very) hypothetical world where 32-bit KVM supports protected guests, assuming a hypercall was made in 64-bit mode is flat out wrong. Reviewed-by: Kai Huang Reviewed-by: Binbin Wu Signed-off-by: Sean Christopherson --- arch/x86/kvm/regs.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/kvm/regs.h b/arch/x86/kvm/regs.h index f22b3a8cd483..a57ba26279ed 100644 --- a/arch/x86/kvm/regs.h +++ b/arch/x86/kvm/regs.h @@ -39,12 +39,16 @@ static inline bool is_64_bit_mode(struct kvm_vcpu *vcpu) static inline bool is_64_bit_hypercall(struct kvm_vcpu *vcpu) { +#ifdef CONFIG_X86_64 /* * If running with protected guest state, the CS register is not * accessible. The hypercall register values will have had to been * provided in 64-bit mode, so assume the guest is in 64-bit. */ return vcpu->arch.guest_state_protected || is_64_bit_mode(vcpu); +#else + return false; +#endif } static __always_inline unsigned long kvm_reg_mode_mask(struct kvm_vcpu *vcpu) -- 2.54.0.823.g6e5bcc1fc9-goog