From nobody Sat Feb 14 05:45:14 2026 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 0AFDB13D8B4 for ; Fri, 17 May 2024 17:39:46 +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=1715967588; cv=none; b=rMmL3l5W9jqWO63pK7ZWs9x7KM/DEqe/wxYf70EfwWYaUS6gOpwN/B03UAO9AZueC5NFr28/Jmmnc66j9K4E14Yjcae1qK4rpoEIK73qp35oJC0TynEH/us1UaIEtG9wLxcML4db8Wvt9Y0p7dZkbslL6riu/vnQeQKeA6c+Hg4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715967588; c=relaxed/simple; bh=9p2+z3k+6TgyjKDlNleEqXcUN36cKZjmsbnwqvT7uZM=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=hFipAK5HnJgC0Eh8v+Ks0qY3u9CvzMZ93l7+6MUF+m9SyJpFtUOAuHm2SEDDHKs6f6/ITseeMeEZ1ne8igAjbILPHmBEdnLzaOONxcCVGrw603Npdq7MhunPUXYhurcVwuIKPIRxxCRXItWqk7eo55rVmeqWM97tVxS68bp4Hqc= 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=G82FhUxK; 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="G82FhUxK" Received: by mail-pl1-f201.google.com with SMTP id d9443c01a7336-1ec2c6eae8bso93155725ad.1 for ; Fri, 17 May 2024 10:39:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1715967586; x=1716572386; 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=s4kTj1Xv//RX7ELH5Gm2ht5CFG6yTV867Y6JHJnZkTw=; b=G82FhUxKpm9broRf53twt3QSvC4AXORTQJ5id42ruXXt/uTqGvnU7KrnYmIWYixiof c7u/LkjvZuOJ/9QYoUhSn6VsXoAw7jafSMdIXtSz1gl5/0gHXcWtucN77ZXpnWZvtfQ/ 4iI9gzSSLfEWPFT7JLBp8m1n4u5D2BBcfzKNAuTFPnPnZ4KQ+Ze/PHN/uRWiZg0Ov+QZ D5Rc30Yq5IMl7qu0gJ+hIbTvCMxLdsb6FL5KDvvEjShAuYV4+Fq6BF7a4jL6UfYf2HNn VeWsTKLoAuQmee7BiKTLR7as0779C7jgWnyN1CtBlRZhl5BKodGNV+J14jYezkgo3FSb +TgA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1715967586; x=1716572386; 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=s4kTj1Xv//RX7ELH5Gm2ht5CFG6yTV867Y6JHJnZkTw=; b=sDY+0YQRwFAohluCdu0Ax2CM4HISbEBb8htHvlLl0ulf/MTBtge2zqpYA37fTzNbOb SJ5SDasiAU984i+zcudJCqV77clogyh+y9O7OqCgxY0mL0CXHABNdXTpRPtyYm7urM/j iGStbYcEnUa1oiLCXQUgzanGfHXvRJNYbYlq0nJfKqok/uqfERf0dkdBhsfslvWgvUSl cxpjuw69VGriq7y4Dih4x3gQXZEyEjnPGJ7N2zv2bSQ2VBRTKNfY7nDLPMazShabgKRq rzmqx2d7N3NZbscM+9fzGlKmBwHri0siTTTawF7/h4R1dO/rBdOZzVoQc7g+uPWC4531 r6eg== X-Forwarded-Encrypted: i=1; AJvYcCUrRlWQwtu/hTvuc8fIdhinW6PAlh401vSZnSd8URHf0U1DygdK2SZg0qKCR9yu95z5xDaLefFGd1e7g+DzieftjHpC70nDbeRC/MQI X-Gm-Message-State: AOJu0YxCItRRrIu1ujssIW6C+chOyME71QxOh8eu/vmAdinB7ER8fgBq CIUEjfVpIxm+gtSOiJi3CcrE0YizOS5vjf4ean/Uduy3ORky99IZfkod7nEHUgXnn9G3XuwBPbb ZVw== X-Google-Smtp-Source: AGHT+IFcafYI9QmJB1eHvPXT14ZAn2abKBNyzqvUSDNr31a0Ns45ESpeAxr0qlAqwCFA+PVsS05zj4sIjrA= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a17:903:1d1:b0:1eb:2fb3:fa0c with SMTP id d9443c01a7336-1ef43c13f0amr6903255ad.3.1715967586406; Fri, 17 May 2024 10:39:46 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 17 May 2024 10:38:38 -0700 In-Reply-To: <20240517173926.965351-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240517173926.965351-1-seanjc@google.com> X-Mailer: git-send-email 2.45.0.215.g3402c0e53f-goog Message-ID: <20240517173926.965351-2-seanjc@google.com> Subject: [PATCH v2 01/49] KVM: x86: Do all post-set CPUID processing during vCPU creation From: Sean Christopherson To: Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Hou Wenlong , Kechen Lu , Oliver Upton , Maxim Levitsky , Binbin Wu , Yang Weijiang , Robert Hoo Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" During vCPU creation, process KVM's default, empty CPUID as if userspace set an empty CPUID to ensure consistent and correct behavior with respect to guest CPUID. E.g. if userspace never sets guest CPUID, KVM will never configure cr4_guest_rsvd_bits, and thus create divergent, incorrect, guest- visible behavior due to letting the guest set any KVM-supported CR4 bits despite the features not being allowed per guest CPUID. Note! This changes KVM's ABI, as lack of full CPUID processing allowed userspace to stuff garbage vCPU state, e.g. userspace could set CR4 to a guest-unsupported value via KVM_SET_SREGS. But it's extremely unlikely that this is a breaking change, as KVM already has many flows that require userspace to set guest CPUID before loading vCPU state. E.g. multiple MSR flows consult guest CPUID on host writes, and KVM_SET_SREGS itself already relies on guest CPUID being up-to-date, as KVM's validity check on CR3 consumes CPUID.0x7.1 (for LAM) and CPUID.0x80000008 (for MAXPHYADDR). Furthermore, the plan is to commit to enforcing guest CPUID for userspace writes to MSRs, at which point bypassing sregs CPUID checks is even more nonsensical. Signed-off-by: Sean Christopherson --- arch/x86/kvm/cpuid.c | 2 +- arch/x86/kvm/cpuid.h | 1 + arch/x86/kvm/x86.c | 1 + 3 files changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index f2f2be5d1141..2b19ff991ceb 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -335,7 +335,7 @@ static bool kvm_cpuid_has_hyperv(struct kvm_cpuid_entry= 2 *entries, int nent) #endif } =20 -static void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu) +void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu) { struct kvm_lapic *apic =3D vcpu->arch.apic; struct kvm_cpuid_entry2 *best; diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h index 23dbb9eb277c..0a8b561b5434 100644 --- a/arch/x86/kvm/cpuid.h +++ b/arch/x86/kvm/cpuid.h @@ -11,6 +11,7 @@ extern u32 kvm_cpu_caps[NR_KVM_CPU_CAPS] __read_mostly; void kvm_set_cpu_caps(void); =20 +void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu); void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu); void kvm_update_pv_runtime(struct kvm_vcpu *vcpu); struct kvm_cpuid_entry2 *kvm_find_cpuid_entry_index(struct kvm_vcpu *vcpu, diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index d750546ec934..7adcf56bd45d 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -12234,6 +12234,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu) kvm_xen_init_vcpu(vcpu); kvm_vcpu_mtrr_init(vcpu); vcpu_load(vcpu); + kvm_vcpu_after_set_cpuid(vcpu); kvm_set_tsc_khz(vcpu, vcpu->kvm->arch.default_tsc_khz); kvm_vcpu_reset(vcpu, false); kvm_init_mmu(vcpu); --=20 2.45.0.215.g3402c0e53f-goog