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 EECC057981C; Tue, 8 Sep 2026 16:23:39 +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=1788884622; cv=none; b=GOLmINGRnbn84q3S7d8uD5ZziY0weruzd7/7KVWF3Sgtz4UNBD2lU8SUYDeBXwWy6m/dX3Jkwhf3m0ahgWeAEVj/5FgSZobeUb7S/kcRbBqCNnhaOxVGlHxIxOcf5rTIy2NerHgINAMcmcZFHG1JMmFXIe3PKD7oV3WOf3UBE4U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788884622; c=relaxed/simple; bh=CUFNiF/5y947+lSyvlccR1MDxDZzW2BioQzrsrm2Qto=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Ap7lVY3nKXhUWOz70wlO9MN2tMduoMYKJptuu8Kb6RVoD4l8WD86JUYnPCg8ypgUJ75Cv+deCazfHCiQGJ3nv9+eb5lVFSAJA6s2rvEiQ3byNcyv4gP2tN+Z5qGIAfE/hRPpCgLVwZP89mos/NtZzdVmUWXFFoOYoEjR5aD5brY= 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=N6Ry4fTc; 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="N6Ry4fTc" 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 B414C1477; Tue, 8 Sep 2026 09:23:35 -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 214D83F7B4; Tue, 8 Sep 2026 09:23:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1788884619; bh=CUFNiF/5y947+lSyvlccR1MDxDZzW2BioQzrsrm2Qto=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=N6Ry4fTcgU4eQHixy+4BGrZC4KulzSrwnQRFnZuaZnzv3hbjGqjznzcXXzFGmkHvi gQyjgIenUiTiXfhXLGAtGBnB4tMUuSLlgVK5HsvokijC3TAv7PNxdVT3PjconnGMPV f568LLkwgJJoBsNFGLYhaxXkIf48eErUA0lRbHxs= 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 v17 14/20] KVM: arm64: CCA: Don't expose unsupported capabilities for realm guests Date: Tue, 8 Sep 2026 17:22:17 +0100 Message-ID: <20260908162223.1683432-15-suzuki.poulose@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260908162223.1683432-1-suzuki.poulose@arm.com> References: <20260908162223.1683432-1-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 RMM v2.0 provides no mechanism for the host to perform debug operations on the guest. So limit the extensions that are visible to an allowlist so that only those capabilities we can support are advertised. Signed-off-by: Suzuki K Poulose Signed-off-by: Steven Price --- 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/kvm/arm.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 3dfe0e03fab7a..fbb4d6651ab51 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -137,6 +137,25 @@ int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu) return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE; } +static bool kvm_realm_ext_allowed(long ext) +{ + switch (ext) { + case KVM_CAP_IRQCHIP: + 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_PTRAUTH_ADDRESS: + case KVM_CAP_ARM_PTRAUTH_GENERIC: + case KVM_CAP_SYNC_MMU: + return true; + } + return false; +} + int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap) { @@ -148,6 +167,9 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, if (is_protected_kvm_enabled() && !kvm_pkvm_ext_allowed(kvm, cap->cap)) return -EINVAL; + if (kvm && kvm_vm_is_realm(kvm) && !kvm_realm_ext_allowed(cap->cap)) + return -EINVAL; + switch (cap->cap) { case KVM_CAP_ARM_NISV_TO_USER: r = 0; @@ -407,6 +429,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) if (is_protected_kvm_enabled() && !kvm_pkvm_ext_allowed(kvm, ext)) return 0; + if (kvm && kvm_vm_is_realm(kvm) && !kvm_realm_ext_allowed(ext)) + return 0; + switch (ext) { case KVM_CAP_IRQCHIP: r = vgic_present; -- 2.43.0