From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id EEEAEC9830E for ; Thu, 24 Sep 2026 16:07:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=wD7yF0GAKWRb+mQsUAMmC5FxloKEkaaG7ULvfvONxAo=; b=VMnKNodp8/qV5JqLwUX6gGI+7n nCl8kNhSZ+Ow2GOipHTTuZgvUMpxRLt5DvMmodLTGIhnH57Wr3PjJjgXzKBBe+fPCzNM1ls9ChVuH MyYsuFA0gYYpE9yWU1fP2wkbxwpQZNn37FHLEuSadvleVznfV4o+xWJsfEC7F0L1eaDLfG5BUF+jq T6Ea2ngUlYCmeURiOCQGaFuS+DJPw1HsKmsgmruYud82snKDcVCsKdyM3T5ZSlzNZn1jVnPnux4I/ P4TPYvjUJV+uul8W8jnTOiCiGmK769BeN+inPdZyAKWmOIAyQvRXh11y5bRE8W3UmLmfw1VHTv119 498E/NDg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x9lyp-0000000BXoT-1fN9; Thu, 24 Sep 2026 16:07:27 +0000 Received: from desiato.infradead.org ([2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x9ly8-0000000BXON-3X3H for linux-arm-kernel@bombadil.infradead.org; Thu, 24 Sep 2026 16:06:44 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Transfer-Encoding:MIME-Version :References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=wD7yF0GAKWRb+mQsUAMmC5FxloKEkaaG7ULvfvONxAo=; b=gOaxIB9VJi8ULOLnf1YoPZz8SH dH+/1b/5Z9Gj8xd3EMEYPvmuRigKXVUeuAByusSuJJbZLIxhDyJsK2kruAkacH5JiWknple0KZtro oyhqNBSkXf1vprZ5cAIApS7ppL7f4r+fU8mCnmskCy3EPlou42Uq4eCiaf4fSls1/KieFU91TvJbj sWr8ARUKyAhgsx/uX2fQuPgd1Ic8XP46ila0BYAr0g37XyM+FCtEZ4Rx+Qq0Dapqmk0LpvB69MJtY gJap7yc4vIX0TMgSSXeqhpJV5HE/OESUWROReg1GlSGx9WG3ijv/F6Ye7p34dzxv9FO5Gw0zoh7BZ jxErxZ+w==; Received: from foss.arm.com ([217.140.110.172]) by desiato.infradead.org with esmtp (Exim 4.99.2 #2 (Red Hat Linux)) id 1x9ly5-0000000GAsp-40OR for linux-arm-kernel@lists.infradead.org; Thu, 24 Sep 2026 16:06:43 +0000 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 D44F51E7D; Thu, 24 Sep 2026 09:06:36 -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 654013F86C; Thu, 24 Sep 2026 09:06:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1790266000; bh=qqIjAm5se+qNeiPgYmrOoah+WsJiOdR/osHb0Swv+J8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nDu7cat3hBgepiWbiMSkO3kfnWAYWqPsbHIYDWOKfPWjgvpVMpXzhxHYvT13Vjc18 xzo2b1WLRJ5740MBkNbq/FXR2fnvp+6Jq1Ll3IIvd4451VnlKLxdS5taIHyRxxhYGn 2E3D69CdxmjtXN46A6OK0dTJbpgsG4l9Sq5BaewU= 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, sudeep.holla@arm.com, jonathan.cameron@oss.qualcomm.com, Suzuki K Poulose Subject: [PATCH v20 18/22] KVM: arm64: CCA: Don't expose unsupported capabilities for realm guests Date: Thu, 24 Sep 2026 17:05:00 +0100 Message-ID: <20260924160504.853911-19-suzuki.poulose@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260924160504.853911-1-suzuki.poulose@arm.com> References: <20260924160504.853911-1-suzuki.poulose@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260924_170642_321615_3040A5E6 X-CRM114-Status: GOOD ( 18.74 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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_vm_ioctl_allowed() and move it into arch/arm64/kvm/arm.c. Also add a generic kvm_vm_ext_allowed() to handle pKVM and Realm capability filtering and route them accordingly. Signed-off-by: Suzuki K Poulose --- Changes since v18: * Bail out early for !pKVM && !Realm vms. Use kvm_vm_hyp_is_distrusting() * WARN_ON_ONCE(!kvm), we are only called from kvm_arch_vm_ioctl() with a valid kvm instance. * Move the kvm_realm_ext_allowed() to asm/kvm_rmi.h - Fuad * Rename kvm_arch_vm_*allowed => kvm_vm_*_allowed - Fuad 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/include/asm/kvm_rmi.h | 23 +++++++++++++++ arch/arm64/kvm/arm.c | 49 +++++++++++++++++++++++++++++-- 3 files changed, 69 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/include/asm/kvm_rmi.h b/arch/arm64/include/asm/kvm_rmi.h index 44f5c75a27b5b..6b8b9ee9ea245 100644 --- a/arch/arm64/include/asm/kvm_rmi.h +++ b/arch/arm64/include/asm/kvm_rmi.h @@ -6,6 +6,8 @@ #ifndef __ASM_KVM_RMI_H #define __ASM_KVM_RMI_H +#include + /** * enum realm_state - State of a Realm * @@ -58,4 +60,25 @@ struct realm { void kvm_init_rmi(void); +static inline 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_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; +} + #endif /* __ASM_KVM_RMI_H */ diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 0e77f59ded6d9..106b52e556e20 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -136,6 +136,49 @@ int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu) return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE; } +static inline bool kvm_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. For pKVM and Realm VMs, certain + * ioctls are not allowed. Further, certain features are allowed only for + * non-protected VMs in pKVM. + */ +static inline bool kvm_vm_ioctl_allowed(struct kvm *kvm, unsigned int ioctl) +{ + long ext; + int r; + + /* + * We are guaranteed to be called with a valid kvm instance, as the + * only caller is kvm_arch_vm_ioctl(). Catch any deviations, as we + * rely on the kvm instance below. + */ + if (WARN_ON_ONCE(!kvm)) + return false; + + /* Cover both pKVM host and Realm VMs */ + if (!kvm_vm_hyp_is_distrusting(kvm)) + return true; + + r = kvm_get_cap_for_kvm_ioctl(ioctl, &ext); + if (WARN_ON_ONCE(r < 0)) + return false; + + return kvm_vm_ext_allowed(kvm, ext); +} + int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap) { @@ -144,7 +187,7 @@ 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_vm_ext_allowed(kvm, cap->cap)) return -EINVAL; switch (cap->cap) { @@ -403,7 +446,7 @@ 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_vm_ext_allowed(kvm, ext)) return 0; switch (ext) { @@ -2144,7 +2187,7 @@ 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_vm_ioctl_allowed(kvm, ioctl)) return -EINVAL; switch (ioctl) { -- 2.43.0