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 EA5B12DC791; Fri, 20 Mar 2026 16:39:23 +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=1774024765; cv=none; b=Pm5AeNuZgGKsBV4+HbB67/Dup8vPO5BZ4G3kvRPne8EOPU+p23/KZA2kdHTdPtvSs8F81/5ch+YAev9BByYdP4Va4ijnu1BIyvAL93Ldy1PZMYOstgZqbO6Tq6V+oPUH4cZvyiyaWoZiRZY6NAWbKcqRkyEQRgfP+0Mnx/1c4hw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774024765; c=relaxed/simple; bh=E3dCiClnQemoe20ySw2frD7EM1AeKLqJmvTYJV/veJ8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=cJsWqrKYxTnqlf9Kn++aWBT/JuRpT2sx7yshIxAfnqTfVO1CzbG4Uy32ufCnDoAKSRE0kSz5kplcc2R5c7WJAgHsFytMOEyXRlTNOoDicTvbCLlknNxCn02OOpoH8rTass6Qw6IxRMsazBUaZ6xxt3VNqpvbxJvj18OYXHHqKO4= 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; 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 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 46592165C; Fri, 20 Mar 2026 09:39:17 -0700 (PDT) Received: from [10.1.29.20] (e122027.cambridge.arm.com [10.1.29.20]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 415983F7BD; Fri, 20 Mar 2026 09:39:19 -0700 (PDT) Message-ID: <33150925-095a-485f-83a9-34b6fb9fbd6a@arm.com> Date: Fri, 20 Mar 2026 16:39:16 +0000 Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v13 23/48] KVM: arm64: Expose support for private memory To: Wei-Lin Chang , kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: Catalin Marinas , Marc Zyngier , Will Deacon , James Morse , Oliver Upton , Suzuki K Poulose , 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: <20260318155413.793430-1-steven.price@arm.com> <20260318155413.793430-24-steven.price@arm.com> From: Steven Price Content-Language: en-GB In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 19/03/2026 19:01, Wei-Lin Chang wrote: > On Wed, Mar 18, 2026 at 03:53:47PM +0000, Steven Price wrote: >> Select KVM_GENERIC_MEMORY_ATTRIBUTES and provide the necessary support >> functions. >> >> Signed-off-by: Steven Price >> --- >> Changes since v12: >> * Only define kvm_arch_has_private_mem() when >> CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES is set to avoid build issues >> when KVM is disabled. >> Changes since v10: >> * KVM_GENERIC_PRIVATE_MEM replacd with KVM_GENERIC_MEMORY_ATTRIBUTES. >> Changes since v9: >> * Drop the #ifdef CONFIG_KVM_PRIVATE_MEM guard from the definition of >> kvm_arch_has_private_mem() >> Changes since v2: >> * Switch kvm_arch_has_private_mem() to a macro to avoid overhead of a >> function call. >> * Guard definitions of kvm_arch_{pre,post}_set_memory_attributes() with >> #ifdef CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES. >> * Early out in kvm_arch_post_set_memory_attributes() if the WARN_ON >> should trigger. >> --- >> arch/arm64/include/asm/kvm_host.h | 4 ++++ >> arch/arm64/kvm/Kconfig | 1 + >> arch/arm64/kvm/mmu.c | 24 ++++++++++++++++++++++++ >> 3 files changed, 29 insertions(+) >> >> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h >> index 64304848aad4..1efea996f474 100644 >> --- a/arch/arm64/include/asm/kvm_host.h >> +++ b/arch/arm64/include/asm/kvm_host.h >> @@ -1486,6 +1486,10 @@ struct kvm *kvm_arch_alloc_vm(void); >> >> #define vcpu_is_protected(vcpu) kvm_vm_is_protected((vcpu)->kvm) >> >> +#ifdef CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES >> +#define kvm_arch_has_private_mem(kvm) ((kvm)->arch.is_realm) >> +#endif >> + >> int kvm_arm_vcpu_finalize(struct kvm_vcpu *vcpu, int feature); >> bool kvm_arm_vcpu_is_finalized(struct kvm_vcpu *vcpu); >> >> diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig >> index 4f803fd1c99a..1cac6dfc0972 100644 >> --- a/arch/arm64/kvm/Kconfig >> +++ b/arch/arm64/kvm/Kconfig >> @@ -38,6 +38,7 @@ menuconfig KVM >> select SCHED_INFO >> select GUEST_PERF_EVENTS if PERF_EVENTS >> select KVM_GUEST_MEMFD >> + select KVM_GENERIC_MEMORY_ATTRIBUTES > > Hi, > > I believe we should also add this: > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > index bfa0ab343081..13722f876dcd 100644 > --- a/Documentation/virt/kvm/api.rst > +++ b/Documentation/virt/kvm/api.rst > @@ -6365,7 +6365,7 @@ Returns -EINVAL if called on a protected VM. > ------------------------------- > > :Capability: KVM_CAP_MEMORY_ATTRIBUTES > -:Architectures: x86 > +:Architectures: x86, arm64 > :Type: vm ioctl > :Parameters: struct kvm_memory_attributes (in) > :Returns: 0 on success, <0 on error Good spot. Thanks, Steve > > Thanks, > Wei-Lin Chang > >> help >> Support hosting virtualized guest machines. >> >> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c >> index b705ad6c6c8b..bad93938acdb 100644 >> --- a/arch/arm64/kvm/mmu.c >> +++ b/arch/arm64/kvm/mmu.c >> @@ -2494,6 +2494,30 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, >> return ret; >> } >> >> +#ifdef CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES >> +bool kvm_arch_pre_set_memory_attributes(struct kvm *kvm, >> + struct kvm_gfn_range *range) >> +{ >> + WARN_ON_ONCE(!kvm_arch_has_private_mem(kvm)); >> + return false; >> +} >> + >> +bool kvm_arch_post_set_memory_attributes(struct kvm *kvm, >> + struct kvm_gfn_range *range) >> +{ >> + if (WARN_ON_ONCE(!kvm_arch_has_private_mem(kvm))) >> + return false; >> + >> + if (range->arg.attributes & KVM_MEMORY_ATTRIBUTE_PRIVATE) >> + range->attr_filter = KVM_FILTER_SHARED; >> + else >> + range->attr_filter = KVM_FILTER_PRIVATE; >> + kvm_unmap_gfn_range(kvm, range); >> + >> + return false; >> +} >> +#endif >> + >> void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot) >> { >> } >> -- >> 2.43.0 >>