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 3F460D77882 for ; Fri, 23 Jan 2026 16:47:32 +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: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=o11k5R02f9CxE3eJ5qhGCQ2U/TVdS+Rm6QF6ACvqyYs=; b=KixDprJm2J2sGuGtttg/EK3o5i OnulEudDG0Mq8WgeqxVhnFceDl9HZ9w4A8Lg/AK+bJPoq2NhNME30YOz1suhhAUYmOAXErzy8L4Es K4OA9T3xFM2HhpEbE43Y2KTzqVTWfOccQRrQ/OJNrHTeiNEOKQ/8pAJ8PYf5ghLhB2zxlPu13SAx0 vE1VQ2h5pN/006gYwVvOJMswg76TLf6vTfzdvWQ4D/USCH7A9BJ+2NEux7THLsi+iS4SW4P3IqKCi heaPiUEmyLacAaLGZfmp0fXkRskaKEupWbpIBrAUbRNwPWPwVT5vMBHjIQqp6E+CKQk/mnNIRWzt5 4hlqVDZQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vjKJf-00000009DdG-3lnO; Fri, 23 Jan 2026 16:47:23 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vjKJc-00000009Dcv-4BIW for linux-arm-kernel@lists.infradead.org; Fri, 23 Jan 2026 16:47:22 +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 CA6801476; Fri, 23 Jan 2026 08:47:09 -0800 (PST) Received: from [10.57.67.240] (unknown [10.57.67.240]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 78F1C3F694; Fri, 23 Jan 2026 08:47:09 -0800 (PST) Message-ID: Date: Fri, 23 Jan 2026 16:47:06 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v12 06/46] arm64: RMI: Define the user ABI To: Steven Price , kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: Catalin Marinas , Marc Zyngier , Will Deacon , James Morse , Oliver Upton , Zenghui Yu , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Joey Gouly , Alexandru Elisei , Christoffer Dall , Fuad Tabba , linux-coco@lists.linux.dev, Ganapatrao Kulkarni , Gavin Shan , Shanker Donthineni , Alper Gun , "Aneesh Kumar K . V" , Emi Kisanuki , Vishal Annapurve References: <20251217101125.91098-1-steven.price@arm.com> <20251217101125.91098-7-steven.price@arm.com> Content-Language: en-GB From: Suzuki K Poulose In-Reply-To: <20251217101125.91098-7-steven.price@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260123_084721_143108_F3B938E5 X-CRM114-Status: GOOD ( 29.25 ) 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 Hi Steven On 17/12/2025 10:10, Steven Price wrote: > There is one CAP which identified the presence of CCA, and two ioctls. > One ioctl is used to populate memory and the other is used when user > space is providing the PSCI implementation to identify the target of the > operation. > Could we split these changes to the corresponding implementation patches ? That might give us a full picture of how these UAPIs fit in the bigger picture. > Signed-off-by: Steven Price > --- > Changes since v11: > * Completely reworked to be more implicit. Rather than having explicit > CAP operations to progress the realm construction these operations > are done when needed (on populating and on first vCPU run). > * Populate and PSCI complete are promoted to proper ioctls. > Changes since v10: > * Rename symbols from RME to RMI. > Changes since v9: > * Improvements to documentation. > * Bump the magic number for KVM_CAP_ARM_RME to avoid conflicts. > Changes since v8: > * Minor improvements to documentation following review. > * Bump the magic numbers to avoid conflicts. > Changes since v7: > * Add documentation of new ioctls > * Bump the magic numbers to avoid conflicts > Changes since v6: > * Rename some of the symbols to make their usage clearer and avoid > repetition. > Changes from v5: > * Actually expose the new VCPU capability (KVM_ARM_VCPU_REC) by bumping > KVM_VCPU_MAX_FEATURES - note this also exposes KVM_ARM_VCPU_HAS_EL2! > --- > Documentation/virt/kvm/api.rst | 57 ++++++++++++++++++++++++++++++++++ > include/uapi/linux/kvm.h | 23 ++++++++++++++ > 2 files changed, 80 insertions(+) > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > index 01a3abef8abb..2d5dc7e48954 100644 > --- a/Documentation/virt/kvm/api.rst > +++ b/Documentation/virt/kvm/api.rst > @@ -6517,6 +6517,54 @@ the capability to be present. > > `flags` must currently be zero. > > +4.144 KVM_ARM_VCPU_RMI_PSCI_COMPLETE > +------------------------------------ > + > +:Capability: KVM_CAP_ARM_RMI > +:Architectures: arm64 > +:Type: vcpu ioctl > +:Parameters: struct kvm_arm_rmi_psci_complete (in) > +:Returns: 0 if successful, < 0 on error > + > +:: > + > + struct kvm_arm_rmi_psci_complete { > + __u64 target_mpidr; > + __u32 psci_status; > + __u32 padding[3]; > + }; > + > +Where PSCI functions are handled by user space, the RMM needs to be informed of > +the target of the operation using `target_mpidr`, along with the status > +(`psci_status`). The RMM v1.0 specification defines two functions that require > +this call: PSCI_CPU_ON and PSCI_AFFINITY_INFO. > + > +If the kernel is handling PSCI then this is done automatically and the VMM > +doesn't need to call this ioctl. > + > +4.145 KVM_ARM_RMI_POPULATE > +-------------------------- > + > +:Capability: KVM_CAP_ARM_RMI > +:Architectures: arm64 > +:Type: vm ioctl > +:Parameters: struct kvm_arm_rmi_populate (in) > +:Returns: number of bytes populated, < 0 on error > + > +:: > + > + struct kvm_arm_rmi_populate { > + __u64 base; > + __u64 size; > + __u64 source_uaddr; > + __u32 flags; > + __u32 reserved; > + }; > + > +Populate a region of protected address space by copying the data from the user > +space pointer provided. This is only valid before any VCPUs have been run. > +The ioctl might not populate the entire region and user space may have to > +repeatedly call it (with updated pointers) to populate the entire region. It may be a good idea to spill out the restrictions on calling this, right ? We expect that the source_uaddr is a separate memory area from the "DRAM" (in shared mode) ? Can this be called before/after converting the entire memory of the Guest to Private ? I believe, it must be done after the "initial change all of DRAM to private" ? Suzuki > > .. _kvm_run: > > @@ -8765,6 +8813,15 @@ helpful if user space wants to emulate instructions which are not > This capability can be enabled dynamically even if VCPUs were already > created and are running. > > +7.47 KVM_CAP_ARM_RMI > +-------------------- > + > +:Architectures: arm64 > +:Target: VM > +:Parameters: None > + > +This capability indicates that support for CCA realms is available. > + > 8. Other capabilities. > ====================== > > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index dddb781b0507..8e66ba9c81db 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -974,6 +974,7 @@ struct kvm_enable_cap { > #define KVM_CAP_GUEST_MEMFD_FLAGS 244 > #define KVM_CAP_ARM_SEA_TO_USER 245 > #define KVM_CAP_S390_USER_OPEREXEC 246 > +#define KVM_CAP_ARM_RMI 247 > > struct kvm_irq_routing_irqchip { > __u32 irqchip; > @@ -1628,4 +1629,26 @@ struct kvm_pre_fault_memory { > __u64 padding[5]; > }; > > +/* Available with KVM_CAP_ARM_RMI, only for VMs with KVM_VM_TYPE_ARM_REALM */ > +struct kvm_arm_rmi_psci_complete { > + __u64 target_mpidr; > + __u32 psci_status; > + __u32 padding[3]; > +}; > + > +#define KVM_ARM_VCPU_RMI_PSCI_COMPLETE _IOW(KVMIO, 0xd6, struct kvm_arm_rmi_psci_complete) > + > +/* Available with KVM_CAP_ARM_RMI, only for VMs with KVM_VM_TYPE_ARM_REALM */ > +struct kvm_arm_rmi_populate { > + __u64 base; > + __u64 size; > + __u64 source_uaddr; > + __u32 flags; > + __u32 reserved; > +}; > + > +#define KVM_ARM_RMI_POPULATE_FLAGS_MEASURE (1 << 0) > + > +#define KVM_ARM_RMI_POPULATE _IOW(KVMIO, 0xd7, struct kvm_arm_rmi_populate) > + > #endif /* __LINUX_KVM_H */