From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 3F128413791; Tue, 15 Sep 2026 16:02:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789488178; cv=none; b=uii9F/KEZWGQjbyzLcSP+2CTpBSJdvyWc5aDBse+omGPp1hnM/ZNV97Nc4D50VVZzuiTBksBFT+vMoK/afbC/rVd5h5J0A0DS0NH0xIr/zyQCuWii21RATDZIV+oEU6cWcd/p40nlRb4EM+JEHALiCcKM2rQqqYsVieZ/nAoJYM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789488178; c=relaxed/simple; bh=6jkrogZGSbm4RdA1R7kTYWIwGIAxksB43/2wFkQ0l0M=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=SKituIMF2oVyO2X7wCDSiwPLH/kqQfxzYFr48/lPlQ2wVP5ZV6Z39iKJJj0R9IeXr3E5YgcU0QJs9B8j8wq9wGHHVlT+D6FKs8dw4Cuqxngpajk5Cm9fpGubHstgLQSBz1MpRplXRNHV/o4Xjadv8fwmjgnnBhkg8cxRoNwVdqI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=bR1+20uS; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="bR1+20uS" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 781B415A1; Tue, 15 Sep 2026 09:02:49 -0700 (PDT) Received: from ewhatever.cambridge.arm.com (ewhatever.cambridge.arm.com [10.2.197.99]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 5FEFA3F882; Tue, 15 Sep 2026 09:02:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1789488173; bh=6jkrogZGSbm4RdA1R7kTYWIwGIAxksB43/2wFkQ0l0M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bR1+20uS1/cFWUrmp4PYnvq1nwFrNe0m5t5XuH/4v7LC0f2gew2gBZtGSvrOAUwaA x6a1/pEVTQNMWuLaILtEDNHY7dHY0xEV+IuV9wiFUmyO7zoHW3H6D8Qki/rxeVkyTB jyJoXuUwhsBmzNsv0GTL+hSVzESf4qvdlgP0w4/U= From: Suzuki K Poulose To: kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: maz@kernel.org, will@kernel.org, catalin.marinas@arm.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, steven.price@arm.com, aneesh.kumar@kernel.org, oupton@kernel.org, gshan@redhat.com, joey.gouly@arm.com, tabba@google.com, yuzenghui@huawei.com, linux-coco@lists.linux.dev, gankulkarni@os.amperecomputing.com, sdonthineni@nvidia.com, alpergun@google.com, fj0570is@fujitsu.com, WeiLin.Chang@arm.com, lpieralisi@kernel.org, enju.kohei@fujitsu.com, Suzuki K Poulose Subject: [PATCH v18 20/23] KVM: arm64: CCA: Don't expose unsupported capabilities for realm guests Date: Tue, 15 Sep 2026 17:01:38 +0100 Message-ID: <20260915160141.3543048-21-suzuki.poulose@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260915160141.3543048-1-suzuki.poulose@arm.com> References: <20260915160141.3543048-1-suzuki.poulose@arm.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Limit the capabilities that are allowed for Realm VMs. Similarly block the vm_ioctls backed by the capabilities. Repurpose the kvm_pkvm_ioctl_allowed() to support both pKVM and Realm ioctls. Rename the helper to kvm_arch_vm_ioctl_allowed() and move it into arch/arm64/kvm/arm.c. Also add a generic kvm_arch_vm_ext_allowed() to handle pKVM and Realm capability filtering. Signed-off-by: Suzuki K Poulose --- Changes since v17: * Drop superfluous !kvm check from kvm_vm_ioctl_enable_cap() - Sashiko * Drop KVM_CAP_CREATE_IRQCHIP, as we don't support VGIC_V2 for Realms * Filter out the vm_ioctls that are based on blocked cap. * Repurpose the pkvm plumbing for filtering the caps and ioctl to generic and plumb the Realm support in Changes since v13: * Add missing check in kvm_vm_ioctl_enable_cap(). Changes since v10: * Add a kvm_realm_ext_allowed() function which limits which extensions are exposed to an allowlist. This removes the need for special casing various extensions. Changes since v7: * Remove the helper functions and inline the kvm_is_realm() check with a ternary operator. * Rewrite the commit message to explain this patch. --- arch/arm64/include/asm/kvm_pkvm.h | 19 ---------- arch/arm64/kvm/arm.c | 58 +++++++++++++++++++++++++++++-- 2 files changed, 55 insertions(+), 22 deletions(-) diff --git a/arch/arm64/include/asm/kvm_pkvm.h b/arch/arm64/include/asm/kvm_pkvm.h index e4ea80711bec6..1bc4fe2726e9b 100644 --- a/arch/arm64/include/asm/kvm_pkvm.h +++ b/arch/arm64/include/asm/kvm_pkvm.h @@ -53,25 +53,6 @@ static inline bool kvm_pkvm_ext_allowed(struct kvm *kvm, long ext) } } -/* - * Check whether the KVM VM IOCTL is allowed in pKVM. - * - * Certain features are allowed only for non-protected VMs in pKVM, which is why - * this takes the VM (kvm) as a parameter. - */ -static inline bool kvm_pkvm_ioctl_allowed(struct kvm *kvm, unsigned int ioctl) -{ - long ext; - int r; - - r = kvm_get_cap_for_kvm_ioctl(ioctl, &ext); - - if (WARN_ON_ONCE(r < 0)) - return false; - - return kvm_pkvm_ext_allowed(kvm, ext); -} - extern struct memblock_region kvm_nvhe_sym(hyp_memory)[]; extern unsigned int kvm_nvhe_sym(hyp_memblock_nr); diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 8ed7dd1ce446c..df0aa66b6f5ed 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -136,6 +136,58 @@ int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu) return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE; } +static inline bool kvm_realm_ext_allowed(long ext) +{ + switch (ext) { + case KVM_CAP_ARM_PSCI: + case KVM_CAP_ARM_PSCI_0_2: + case KVM_CAP_NR_VCPUS: + case KVM_CAP_MAX_VCPUS: + case KVM_CAP_MAX_VCPU_ID: + case KVM_CAP_MSI_DEVID: + case KVM_CAP_ARM_VM_IPA_SIZE: + case KVM_CAP_ARM_SVE: + case KVM_CAP_ONE_REG: + case KVM_CAP_ARM_PTRAUTH_ADDRESS: + case KVM_CAP_ARM_PTRAUTH_GENERIC: + case KVM_CAP_SYNC_MMU: + return true; + } + return false; +} + +static inline bool kvm_arch_vm_ext_allowed(struct kvm *kvm, long ext) +{ + /* + * We could be called with kvm as NULL, so can't use kvm_vm_* for pKVM + * flavors + */ + if (is_protected_kvm_enabled()) + return kvm_pkvm_ext_allowed(kvm, ext); + else if (kvm && kvm_vm_is_realm(kvm)) + return kvm_realm_ext_allowed(ext); + else + return true; +} + +/* + * Check whether the KVM VM IOCTL is allowed. + * + * Certain features are allowed only for non-protected VMs in pKVM, which is why + * this takes the VM (kvm) as a parameter. + */ +static inline bool kvm_arch_vm_ioctl_allowed(struct kvm *kvm, unsigned int ioctl) +{ + long ext; + int r; + + r = kvm_get_cap_for_kvm_ioctl(ioctl, &ext); + if (WARN_ON_ONCE(r < 0)) + return false; + + return kvm_arch_vm_ext_allowed(kvm, ext); +} + int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap) { @@ -144,7 +196,7 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, if (cap->flags) return -EINVAL; - if (is_protected_kvm_enabled() && !kvm_pkvm_ext_allowed(kvm, cap->cap)) + if (!kvm_arch_vm_ext_allowed(kvm, cap->cap)) return -EINVAL; switch (cap->cap) { @@ -418,7 +470,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) { int r; - if (is_protected_kvm_enabled() && !kvm_pkvm_ext_allowed(kvm, ext)) + if (!kvm_arch_vm_ext_allowed(kvm, ext)) return 0; switch (ext) { @@ -2150,7 +2202,7 @@ int kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) void __user *argp = (void __user *)arg; struct kvm_device_attr attr; - if (is_protected_kvm_enabled() && !kvm_pkvm_ioctl_allowed(kvm, ioctl)) + if (!kvm_arch_vm_ioctl_allowed(kvm, ioctl)) return -EINVAL; switch (ioctl) { -- 2.43.0