From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 09E3B4D990D for ; Wed, 30 Sep 2026 13:48:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790776095; cv=none; b=RQaioJK4z4r9GBb+vEdPlZsef9MtS7lrrp3a6guFEkauqox6wbr5Q/lgFO41g1JmPXJsBmvGBbuhuTKrQaX9kSdaul2jHweUtRvLT16Q6H3HPaYvIaIESBOIvfNR/YkHUK/X2ZNk/HC8YZM6mPLLHe2BMY3plKN8ebT1gsWNBR8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790776095; c=relaxed/simple; bh=Wg8JKSDQDu58Sn7lILSHljoeFBeUnio47gRVTVUdwgc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=nVvXCajXc4c+akIU23mvEcrLUY3zUr4dexpBNsF/HZN5ZhBXDxPpKq+hhY/l7jJnm+Y6IjNkT6WrBy1yojzxaMtsmGwfmIRso4S2zQSfuzwuYRJpqkqEqT8emR+RD2THp6KyTeTxQdaYxf7Mv+WJzVQgtStWPKMagsyP+vPpKUc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=A/2ExVuJ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="A/2ExVuJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EFCE51F00898; Wed, 30 Sep 2026 13:48:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790776082; bh=xq6FViZgqbxhTaPQjnrnGEZuwl8OjT04weu/PJN47hE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=A/2ExVuJN7VvS4ScATrTlOZOYc38Jc6fleuNLGT77ABjQgatULFTHr1HCtJE2QJVc Pg16PFuTvWULFULL46gDOPJykWSXu0ln6Ic5p1InPxXDx3fBnUIV8ZK8dT+CiD9q1I bv2xcMl6cDk61x6daSTK1FM+K2wVJGzTLgskd3XuUjEENRe9LxbdbwqFwygCdmeuQI uNYjQS34KS2oO1LUHwvhbAZRvfptQLOOIdFPH6wJjnee9A9rn+h5HgJq47LE58Owuj ENZco25LVz9MekFPDAgLrn8SLAhbHXz5zzgIhikIr4/X6LBx/3/wwZlXhcanmAlGqa M2YyfKHYGEGWw== From: Sasha Levin To: stable@vger.kernel.org Cc: Sean Christopherson , Vitaly Kuznetsov , Sasha Levin Subject: [PATCH 7.2.y 4/6] KVM: x86: Reject nested CAP enablement if nested virtualization is disabled Date: Wed, 30 Sep 2026 09:47:55 -0400 Message-ID: <20260930134757.1797371-4-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260930134757.1797371-1-sashal@kernel.org> References: <2026092938-mantis-spearfish-5a96@gregkh> <20260930134757.1797371-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Sean Christopherson [ Upstream commit b65699be2c606d2687593516d93e66d16a713b61 ] Add a flag to explicitly track if nested virtualization is enabled, and use it enumerate that various nested CAPs are unsupported, and to reject enablement of said CAPs. When the nested ops hooks were moved to their own structure, KVM's NULL-by-default behavior was deliberately dropped, with the changelog asserting that all was well. That wasn't quite true; there is no danger to KVM, but now KVM is over-reporting support for KVM_CAP_NESTED_STATE and KVM_CAP_HYPERV_ENLIGHTENED_VMCS. Fixes: 33b22172452f ("KVM: x86: move nested-related kvm_x86_ops to a separate struct") Reviewed-by: Vitaly Kuznetsov Link: https://patch.msgid.link/20260630202828.440724-2-seanjc@google.com Signed-off-by: Sean Christopherson Stable-dep-of: c1214f293d77 ("KVM: x86: Fill kvm_run exit fields in common get_nested_state_pages() error paths") Signed-off-by: Sasha Levin --- arch/x86/include/asm/kvm_host.h | 2 ++ arch/x86/kvm/hyperv.c | 3 ++- arch/x86/kvm/svm/svm.c | 1 + arch/x86/kvm/vmx/vmx.c | 1 + arch/x86/kvm/x86.c | 12 +++++++----- 5 files changed, 13 insertions(+), 6 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index a1f756ea0172a..1d5925fad271d 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -2019,6 +2019,8 @@ struct kvm_x86_ops { }; struct kvm_x86_nested_ops { + bool enabled; + void (*leave_nested)(struct kvm_vcpu *vcpu); bool (*is_exception_vmexit)(struct kvm_vcpu *vcpu, u8 vector, u32 error_code); diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index 5f43ae345f87c..00915958c7e2f 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -2800,7 +2800,8 @@ int kvm_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid, }; int i, nent = ARRAY_SIZE(cpuid_entries); - if (kvm_x86_ops.nested_ops->get_evmcs_version) + if (kvm_x86_ops.nested_ops->enabled && + kvm_x86_ops.nested_ops->get_evmcs_version) evmcs_ver = kvm_x86_ops.nested_ops->get_evmcs_version(vcpu); if (cpuid->nent < nent) diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 03fb9d7231c8d..d1423bab1a3aa 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -5662,6 +5662,7 @@ static __init int svm_hardware_setup(void) if (r) return r; } + svm_nested_ops.enabled = nested; /* * KVM's MMU doesn't support using 2-level paging for itself, and thus diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 8b75c70e60d26..61243d16febf0 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -8771,6 +8771,7 @@ __init int vmx_hardware_setup(void) if (r) return r; } + vmx_nested_ops.enabled = nested; kvm_set_posted_intr_wakeup_handler(pi_wakeup_handler); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 9822ff0450bb2..1e145e448b593 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4517,7 +4517,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) r &= ~KVM_X2APIC_ENABLE_SUPPRESS_EOI_BROADCAST; break; case KVM_CAP_NESTED_STATE: - r = kvm_x86_ops.nested_ops->get_state ? + r = kvm_x86_ops.nested_ops->enabled ? kvm_x86_ops.nested_ops->get_state(NULL, NULL, 0) : 0; break; #ifdef CONFIG_KVM_HYPERV @@ -4525,7 +4525,8 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) r = kvm_x86_ops.enable_l2_tlb_flush != NULL; break; case KVM_CAP_HYPERV_ENLIGHTENED_VMCS: - r = kvm_x86_ops.nested_ops->enable_evmcs != NULL; + r = kvm_x86_ops.nested_ops->enabled && + kvm_x86_ops.nested_ops->enable_evmcs != NULL; break; #endif case KVM_CAP_SMALLER_MAXPHYADDR: @@ -5567,7 +5568,8 @@ static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu, uint16_t vmcs_version; void __user *user_ptr; - if (!kvm_x86_ops.nested_ops->enable_evmcs) + if (!kvm_x86_ops.nested_ops->enabled || + !kvm_x86_ops.nested_ops->enable_evmcs) return -ENOTTY; r = kvm_x86_ops.nested_ops->enable_evmcs(vcpu, &vmcs_version); if (!r) { @@ -6067,7 +6069,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp, u32 user_data_size; r = -EINVAL; - if (!kvm_x86_ops.nested_ops->get_state) + if (!kvm_x86_ops.nested_ops->enabled) break; BUILD_BUG_ON(sizeof(user_data_size) != sizeof(user_kvm_nested_state->size)); @@ -6097,7 +6099,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp, int idx; r = -EINVAL; - if (!kvm_x86_ops.nested_ops->set_state) + if (!kvm_x86_ops.nested_ops->enabled) break; r = -EFAULT; -- 2.53.0