From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 173F73A7F72 for ; Thu, 5 Mar 2026 14:45:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772721955; cv=none; b=C6LIlA9jugD71v/nT4LfjHgAqaFNg9haL5jBYbHd8jPdbuj8PjGuhO9ArAy5M5nNCglwcH23NKoOh6VTN2zHQ95ftNDf0i+c+VYKc3lbRtH9am4i10MzN6mIQtvrLXmd+Yp1oqXSBjVPL8XLgyjbkxKma6979Qmg3beznl9KxF0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772721955; c=relaxed/simple; bh=VQdIsZC5GfRSg/vKbiwcTXem/SqGLlNtcZq7UMf4eDI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=SXxl04RYokB2ie7yOlaknL86rE9jB4d0Be+PAsjoJkfbgC5gTbdfgpv0Fi82oDbOq9LFoXU6zv5rzKEiLvV5Uwt4J/Y9a2nyWytIbzeMsC6jL7ycNlQDvkBf95E55hQbYYkohHrD5ZeWqEGV+l31O+zOx+VU93Xay9t6TUVS4jE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JzIfdT/X; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JzIfdT/X" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E149DC2BCB3; Thu, 5 Mar 2026 14:45:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772721954; bh=VQdIsZC5GfRSg/vKbiwcTXem/SqGLlNtcZq7UMf4eDI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JzIfdT/XLng0DYfnf80ryTE063ykp+nj/5yYUI2/pgHzwCuHXWgVIEdyJV8Bk1gAF s3cIxAtSbPDsphj/nXhwURUSRfG4LzAKjR9G9K7Zo/KqiOYn4TqErpohzgt6bobicc BCTHRCta++cgVGD9mLPWt6B1n4yJFet96KS9OBF2PIGipKk11GoRJxDWiqWTZs/Dwa 0cNV+pAAD4DyFyrD5Lj3JneLOqfcjzblf2zK+mv2o8FDHPw7Q0Oygxdz6+6XAmQMct 6rKEqRhSZTosFjyQE/PnpuEAj4gjG/AiiOlzt2uiHtap9vlN5bulP7a4RCwGKHXkRX r4JRTJQ/b7OZw== From: Will Deacon To: kvmarm@lists.linux.dev Cc: linux-arm-kernel@lists.infradead.org, Will Deacon , Marc Zyngier , Oliver Upton , Joey Gouly , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Quentin Perret , Fuad Tabba , Vincent Donnefort , Mostafa Saleh , Alexandru Elisei Subject: [PATCH v3 30/36] KVM: arm64: Allow userspace to create protected VMs when pKVM is enabled Date: Thu, 5 Mar 2026 14:43:43 +0000 Message-ID: <20260305144351.17071-31-will@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260305144351.17071-1-will@kernel.org> References: <20260305144351.17071-1-will@kernel.org> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Introduce a new VM type for KVM/arm64 to allow userspace to request the creation of a "protected VM" when the host has booted with pKVM enabled. For now, this depends on CONFIG_EXPERT and results in a taint on first use as many aspects of a protected VM are not yet protected! Signed-off-by: Will Deacon --- arch/arm64/include/asm/kvm_pkvm.h | 2 +- arch/arm64/kvm/Kconfig | 10 ++++++++++ arch/arm64/kvm/arm.c | 8 +++++++- arch/arm64/kvm/mmu.c | 3 --- arch/arm64/kvm/pkvm.c | 11 ++++++++++- include/uapi/linux/kvm.h | 5 +++++ 6 files changed, 33 insertions(+), 6 deletions(-) diff --git a/arch/arm64/include/asm/kvm_pkvm.h b/arch/arm64/include/asm/kvm_pkvm.h index 7041e398fb4c..2954b311128c 100644 --- a/arch/arm64/include/asm/kvm_pkvm.h +++ b/arch/arm64/include/asm/kvm_pkvm.h @@ -17,7 +17,7 @@ #define HYP_MEMBLOCK_REGIONS 128 -int pkvm_init_host_vm(struct kvm *kvm); +int pkvm_init_host_vm(struct kvm *kvm, unsigned long type); int pkvm_create_hyp_vm(struct kvm *kvm); bool pkvm_hyp_vm_is_created(struct kvm *kvm); void pkvm_destroy_hyp_vm(struct kvm *kvm); diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig index 7d1f22fd490b..e71f7fb6e89a 100644 --- a/arch/arm64/kvm/Kconfig +++ b/arch/arm64/kvm/Kconfig @@ -82,4 +82,14 @@ config PTDUMP_STAGE2_DEBUGFS If in doubt, say N. +config PROTECTED_VM_UAPI + bool "Expose protected VMs to userspace (experimental)" + depends on KVM && EXPERT + help + Say Y here to enable experimental (i.e. in development) + support for creating protected virtual machines using KVM's + KVM_CREATE_VM ioctl() when booted with pKVM enabled. + + Unless you are a KVM developer, say N. + endif # VIRTUALIZATION diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 3589fc08266c..c2b666a46893 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -203,6 +203,9 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) { int ret; + if (type & ~KVM_VM_TYPE_ARM_MASK) + return -EINVAL; + mutex_init(&kvm->arch.config_lock); #ifdef CONFIG_LOCKDEP @@ -234,9 +237,12 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) * If any failures occur after this is successful, make sure to * call __pkvm_unreserve_vm to unreserve the VM in hyp. */ - ret = pkvm_init_host_vm(kvm); + ret = pkvm_init_host_vm(kvm, type); if (ret) goto err_uninit_mmu; + } else if (type & KVM_VM_TYPE_ARM_PROTECTED) { + ret = -EINVAL; + goto err_uninit_mmu; } kvm_vgic_early_init(kvm); diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 4e64528d86a6..7655e4c61c4e 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -881,9 +881,6 @@ static int kvm_init_ipa_range(struct kvm_s2_mmu *mmu, unsigned long type) u64 mmfr0, mmfr1; u32 phys_shift; - if (type & ~KVM_VM_TYPE_ARM_IPA_SIZE_MASK) - return -EINVAL; - phys_shift = KVM_VM_TYPE_ARM_IPA_SIZE(type); if (is_protected_kvm_enabled()) { phys_shift = kvm_ipa_limit; diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c index da0a45dab203..d1eb6e23367e 100644 --- a/arch/arm64/kvm/pkvm.c +++ b/arch/arm64/kvm/pkvm.c @@ -219,9 +219,13 @@ void pkvm_destroy_hyp_vm(struct kvm *kvm) mutex_unlock(&kvm->arch.config_lock); } -int pkvm_init_host_vm(struct kvm *kvm) +int pkvm_init_host_vm(struct kvm *kvm, unsigned long type) { int ret; + bool protected = type & KVM_VM_TYPE_ARM_PROTECTED; + + if (protected && !IS_ENABLED(CONFIG_PROTECTED_VM_UAPI)) + return -EINVAL; if (pkvm_hyp_vm_is_created(kvm)) return -EINVAL; @@ -236,6 +240,11 @@ int pkvm_init_host_vm(struct kvm *kvm) return ret; kvm->arch.pkvm.handle = ret; + kvm->arch.pkvm.is_protected = protected; + if (protected) { + pr_warn_once("kvm: protected VMs are for development only, tainting kernel\n"); + add_taint(TAINT_USER, LOCKDEP_STILL_OK); + } return 0; } diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 65500f5db379..50348efe3384 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -699,6 +699,11 @@ struct kvm_enable_cap { #define KVM_VM_TYPE_ARM_IPA_SIZE_MASK 0xffULL #define KVM_VM_TYPE_ARM_IPA_SIZE(x) \ ((x) & KVM_VM_TYPE_ARM_IPA_SIZE_MASK) + +#define KVM_VM_TYPE_ARM_PROTECTED (1UL << 31) +#define KVM_VM_TYPE_ARM_MASK (KVM_VM_TYPE_ARM_IPA_SIZE_MASK | \ + KVM_VM_TYPE_ARM_PROTECTED) + /* * ioctls for /dev/kvm fds: */ -- 2.53.0.473.g4a7958ca14-goog