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 554493074B1 for ; Mon, 5 Jan 2026 15:51:10 +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=1767628271; cv=none; b=VyQZgoSed//U/lCH0mH9jSyvIrNOInPQk+OugVcyWb9D35FEgFQah5jHL40FEC+fDGudMEoDUX4VzwvxS1MKF+E8vwVdyRB4zMc6730l+3rUqL9wN31dW6Cgu49tTwFe5nQIbRwnxfaOiW6NzHnh3mhZHFIpwBaoTkBIsGwdljI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767628271; c=relaxed/simple; bh=PIpPot3/pD5boU8yFENrmwU3G9yh83bvfpd7l2yKSuA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=aT5yJXOMR+8yt+3hrnEBeOaROa14IIKY1+3McziOm19DU0d2wA/fya5kGehu2fsIAAW9sOMgrbbCpqIly8JFKNetKxI/13pQtnca6Pit+Gz3YQ3jNAHfuxDZyLEruk0p8PYfbwg8/jqXMtvIwJVP7z6cF/CXsniOO/6crXWgmkU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=rSGSPNUb; 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="rSGSPNUb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4F75DC116D0; Mon, 5 Jan 2026 15:51:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1767628270; bh=PIpPot3/pD5boU8yFENrmwU3G9yh83bvfpd7l2yKSuA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rSGSPNUbL2hvK9MU8TEnvyTJ6aWhN/RYDnGXpOtHAfYOGSTcMQASlCDRPAcibyOCu jV9OZ/KbkhkFIVJzP5DwRLAX37KD+071ryOjOhWRFIMZO/WFoQPpyxRWXT67mH6mvw 70Ld7RpkfPABHlTUIP1zgKuokZAKxa52e4/2MCOYGESXVtJbvQba+OtmBCh5bZJCcb HdV9Cez9epDIvhI2QGiD4JsTlInVQEHn5rRBvxnUERPeEOg5bP+Es8UPQGQbJcXX2p k4577eZ5YdQgezr3x7xwS7YrofrntquU23jBJ5fZEV4jcLqJUZrFgB08oCuuZuCMjl HWFVMTTBztUjQ== 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 Subject: [PATCH 26/30] KVM: arm64: Allow userspace to create protected VMs when pKVM is enabled Date: Mon, 5 Jan 2026 15:49:34 +0000 Message-ID: <20260105154939.11041-27-will@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260105154939.11041-1-will@kernel.org> References: <20260105154939.11041-1-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 5a71d25febca..507d9c53e2eb 100644 --- a/arch/arm64/include/asm/kvm_pkvm.h +++ b/arch/arm64/include/asm/kvm_pkvm.h @@ -16,7 +16,7 @@ #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 4f803fd1c99a..47fa06c9da94 100644 --- a/arch/arm64/kvm/Kconfig +++ b/arch/arm64/kvm/Kconfig @@ -83,4 +83,14 @@ 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 4f80da0c0d1d..66f472774da7 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -157,6 +157,9 @@ 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 @@ -188,9 +191,12 @@ 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_free_cpumask; + } else if (type & KVM_VM_TYPE_ARM_PROTECTED) { + ret = -EINVAL; + goto err_free_cpumask; } kvm_vgic_early_init(kvm); diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index fafedcbd516d..3c7aca86961d 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 14865907610c..6d6b1ef1cc62 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 dddb781b0507..9316a827a826 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -689,6 +689,11 @@ 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: */ -- 2.52.0.351.gbe84eed79e-goog