From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C4FF33ACF12 for ; Tue, 1 Sep 2026 04:29:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788236979; cv=none; b=O04cI89ToEyMI5dahAhV1CRi5NmmKgThV15VAZ3TK/dBFY77UATzx5EpZnqRCuyYad326s/m3Hl3VfSVYGtfPVZnwEuD87z19toMiKHrE2xtuwZgeyniWqJkc8fCMb+fjErQ8h9BV9DlBzfw+mQDtX9c9tDviT3LVzWSK95YrDI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788236979; c=relaxed/simple; bh=b/q72RLD9lBRxi2VmlFM4dWbgfCb6GrTRD2Ri5Ba41s=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=MUUjaiSR1nGT1tUephBZQNVBm1D5Zv8T1F7NW7DhBtqU/mqOrX0Tcb/gGpy2h7e603gdpL/O8gNYA0WlPh5XKG2TBCDD+cfrpiyyu25kU32XvwBB4j6EH2zK7QWQDwngNVpaxPeqFl0hvANkMyN5kN+rxCg0NK4q4vReUOtRrp8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=MCINri1g; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=hSMaV6uR; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="MCINri1g"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="hSMaV6uR" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1788236976; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=YCQU+V95xqEH8EbNTciL/CsMqe3BTX/wUO0rCYM10FE=; b=MCINri1gBAl2Y5AU/X1mZ1x7bpSitYjHljQdXJiSZq3VhDLv16nW4uOgMIg0gucgFmYE2u ZXrQNABPzwOxj4wWUEqxn5MnaSRFbYVPufXMYTuH8SEiKNxoP3vtUYDpWP9sGz9s/qvbnj 1eq4Xl+xPebXwsoQlVbu5Zo9z8oLTAU= Received: from mail-pg1-f200.google.com (mail-pg1-f200.google.com [209.85.215.200]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-622-K5r9Gh8KP-yp1KQkq1U-rA-1; Tue, 01 Sept 2026 00:29:35 -0400 X-MC-Unique: K5r9Gh8KP-yp1KQkq1U-rA-1 X-Mimecast-MFC-AGG-ID: K5r9Gh8KP-yp1KQkq1U-rA_1788236975 Received: by mail-pg1-f200.google.com with SMTP id 41be03b00d2f7-cbb467e56aaso3809192a12.1 for ; Mon, 31 Aug 2026 21:29:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1788236975; x=1788841775; darn=vger.kernel.org; h=content-transfer-encoding:content-type:in-reply-to:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:from:to:cc:subject:date:message-id:reply-to :content-type; bh=YCQU+V95xqEH8EbNTciL/CsMqe3BTX/wUO0rCYM10FE=; b=hSMaV6uRCq+5w4vlUZbgt5hVWo1Lm18O/mQfVV7TtSUED35DSCLHk0mU99w0LAg7Cq /zl7ZdCWr9+Cb/ci3Dys4JqepeG6BTAnknPca17777XmC8BTHIxaVta+macL5LEYW4BH XQTQAaJepQubshDGZJnvgMf24GPg5E754Gz/C8E9KE0tMwJ6MUpJ1zRhob92/+WOwrXe fFaqEsP9JYuAoAyfQxIg/TtciSbhB2OjoOl02wfda5pVUICvtiRmcZWYmy7kHbZI+3CJ Oi/q1nO17uha+hU3vJskU1U3jYXbErfTtxse0wYYwpN6bHQPLDqzckMI5/daAhb345cZ r2Qg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1788236975; x=1788841775; h=content-transfer-encoding:content-type:in-reply-to:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=YCQU+V95xqEH8EbNTciL/CsMqe3BTX/wUO0rCYM10FE=; b=Z+AfLmekMJLqqct9t/9vaFonJZFEooUGZS9Xp/Lvqhb2vcEwDOzqjtKUF4FRznalL3 y3DC/Ix0TsvKWwaE4XhQmrOSLOI58Lbe8AW4EO2xrB8DGC4hnHVfEHowv4s7zWgZZkqm NLREK7ht/+I9kC/Dao3Gh7Klo1E/3c3Muu+5fj6xakhCMoBoKKHckKaB4SvAoyvbmQay SZBkB0t78VCZaJN8z5OFLnCxvgFX9XyCHXSV8kielamSmdHt2cF1MN5sm7/RZXxXncdO HWetRS+rkR8gTuWxxzNs5BFQN4aMaOtY4ZDnP1H4KJNCNyyiTlv+06Li2WcyL/omlu4+ 1wDw== X-Forwarded-Encrypted: i=1; AKwUvBzLgB/F7cKPJzWT9Smjl0NkEKc3vfC+tkpfkIZ1B8uqa9dtHhuBjEsvPf2/GJXDAzWJiKuzvFzuGDdGZDs=@vger.kernel.org X-Gm-Message-State: AFuF++kgmYMltrUlr2qIXgpW5YOM+zLDetD3GJLoUxakCSTLcmUtzQ75 /inoo/105TqdhGdMP+5Lv2PYQCCX8XxxW2u+jFQVET0hXZulL+kup7Xsjvt4uTBKkqveoAoEVf3 8rdTi3/OV2iMW3OiQVj4Px8MPlX/AV39qKUuF0MnAAUIHEm0bOM82yR587otvu1OcCQ== X-Gm-Gg: AYBFou3DvrfaaqKidCQHVtgv9VgLi6PJsGNyUjJhEsUnoKuUlUj1nwNFsn3jP/IupMQ wcvLURDt9ri+B18jXx13r1sCW8BJbtoGXRJf0tH91L1Fna87LsWiPc6oUr7WIWvj/NVOd2vl7Hz EqP3AM2C9m06/iLZoj7skWrad/8sWtzVz6CcdDuYsvqY3k9a9sxNCJcUMARkBh+4lVrf/nJviJ0 jgLHZ1Z+pOr22Uu0ZamNd8zRPmXYgVxpj47pXMC7I6HSIn2WC+2fMr5S6p4z399OhNeBmsT4+TG bQW/UVp4xoJ6o9It2C8TK6LiHE5kj9wq6zSpX+wJHfvETCee0L4qmJ+PW22U9yVo0JtIWncKuQS qHKky0d57PPDaMExFYxgb3jYqph9DGdj1K8yo0NSglw== X-Received: by 2002:a17:903:2acb:b0:2d9:1c02:5a19 with SMTP id d9443c01a7336-2d94a956b48mr72439895ad.22.1788236974301; Mon, 31 Aug 2026 21:29:34 -0700 (PDT) X-Received: by 2002:a17:903:2acb:b0:2d9:1c02:5a19 with SMTP id d9443c01a7336-2d94a956b48mr72439155ad.22.1788236973766; Mon, 31 Aug 2026 21:29:33 -0700 (PDT) Received: from [192.168.68.51] (n175-34-8-244.mrk21.qld.optusnet.com.au. [175.34.8.244]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-3286f95a847sm30663601eec.17.2026.08.31.21.29.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 31 Aug 2026 21:29:33 -0700 (PDT) Message-ID: <8e699e2d-c04c-4ff7-98a3-c01e573ee817@redhat.com> Date: Tue, 1 Sep 2026 14:29:22 +1000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v16 15/45] KVM: arm64: CCA: Don't expose unsupported capabilities for realm guests To: Steven Price , kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: Suzuki K Poulose , 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 , Shanker Donthineni , Alper Gun , "Aneesh Kumar K . V" , Emi Kisanuki , Vishal Annapurve , WeiLin.Chang@arm.com, Lorenzo Pieralisi References: <20260803134403.80630-1-steven.price@arm.com> <20260803134403.80630-16-steven.price@arm.com> Content-Language: en-US From: Gavin Shan In-Reply-To: <20260803134403.80630-16-steven.price@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Steve, On 8/3/26 11:43 PM, Steven Price wrote: > From: Suzuki K Poulose > > 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 | 26 ++++++++++++++++++++++++++ > 1 file changed, 26 insertions(+) > > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c > index c4d906861736..6f39831dcf5d 100644 > --- a/arch/arm64/kvm/arm.c > +++ b/arch/arm64/kvm/arm.c > @@ -135,6 +135,26 @@ 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_ARM_RMI: > + case KVM_CAP_SYNC_MMU: > + return true; > + } > + return false; > +} > + Nitpick: The code can be simplified a bit if @kvm is passed to kvm_realm_ext_allowed(). In this way, kvm_realm_ext_allowed() looks similar to kvm_pkvm_ext_allowed(). static bool kvm_realm_ext_allowed(struct kvm *kvm, long ext) { if (!kvm || !kvm_is_realm(kvm)) return true; switch (ext) { case KVM_CAP_IRQCHIP: : case KVM_CAP_SYNC_MMU: return true; } return false; } > int kvm_vm_ioctl_enable_cap(struct kvm *kvm, > struct kvm_enable_cap *cap) > { > @@ -146,6 +166,9 @@ 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_is_realm(kvm) && !kvm_realm_ext_allowed(cap->cap)) > + return -EINVAL; > + if (!kvm_realm_ext_allowed(kvm, cap->cap)) return -EINVAL; > switch (cap->cap) { > case KVM_CAP_ARM_NISV_TO_USER: > r = 0; > @@ -380,6 +403,9 @@ 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_is_realm(kvm) && !kvm_realm_ext_allowed(ext)) > + return 0; > + if (!kvm_realm_ext_allowed(kvm, ext)) return 0; > switch (ext) { > case KVM_CAP_IRQCHIP: > r = vgic_present; Thanks, Gavin