From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=217.140.110.172 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794224138; b=bzWddBR9rroE3V3wtmAiBFqJgj5d1QW4E0RIajNe+/OIEUQMgOoeCCw82czUe7Yf9/gO y0SZXwAXfo5/2gDluQIzA5B3AYc1ODmdX4OzRa9GJbBhdgWzdMZUC9tbE9UVTjwHbH8ac z/K1tPYPFfuWeVENyzZAaFD89XbskjZHfEcsCtUsG42z3FnXay0M3z9KLzJZBgqicg8aW bgNBAftX4PfufGDODpIew4GY/OmL7HFLYZkhtvxKUKJbOo7TKigm4d+4E/9/kXZF96T+I 54coJQpMgXu1U84OivReALM4E2nZe3mO2jNucuat1WGvVluw91k1wiTL2fQNk8d5u/w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794224138; h=DMARC-Filter:Received:Received:DKIM-Signature:Message-ID:Date: MIME-Version:User-Agent:Subject:To:Cc:References:Content-Language: From:In-Reply-To:Content-Type:Content-Transfer-Encoding; bh=PYV844ivqJ39fhXbpbQJt7ThrmrdZ/Uef1Hl7B/7mic=; b=f29hFGyLNqhAUEjwpKAOXEpKakxperivik7g0ipk0/maQLsRP3oudY2PdPYsHoST4pRL UKnjnQks3WXi2hFEx8cBbboyhgTK11MyXbexyVN5WlBckmZRW0GN9yXpudmOiLtjQ7TSf 6JKSIPZShK8NE8HPP5fjWoEjL8E4759ZECGn7yB2tW5IyuGaPUWC63jh8uX4Ryw6Gg1YZ NbIDVWrBiTUd05bQd9jkWxGDJlrY/rkofH1S8d/4AXVhaxbsJzeqQ+BgHFikr2Bik4xZm GCIxmn3mi633SFYhJHSuqpffmWt6XdpbDEsZqyBsF7G4gydobjE2+I+afEJN4SqfMFA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass header.d=arm.com header.i=@arm.com header.a=rsa-sha256 header.s=foss header.b=Qzcy7j5c; arc=none smtp.remote-ip=217.140.110.172 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 41A81606A322; Mon, 9 Nov 2026 11:35:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 41A81606A322 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.a=rsa-sha256 header.s=foss header.b=Qzcy7j5c 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 37FB61516; Mon, 9 Nov 2026 03:35:33 -0800 (PST) Received: from [10.2.197.99] (ewhatever.cambridge.arm.com [10.2.197.99]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B59B93F85F; Mon, 9 Nov 2026 03:35:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1794224136; bh=rTLHWsiv8pph/dAfc4DcKVgal8O6MwfZfU2M1D232cA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Qzcy7j5c8+tbgnD1Z9hB0H2xfYVSag9SEoaDEDoibA7M1o5laQrfJaS2pa7i5zACm 0Wgo+QHOtul0e27z4on0wY4fO+kWBT/9IiUgRtGqRXOU8DsIHZh5o41QjjaZjx8WoB tleUJKwVUK/luuLMar6jw5SH1NCbv5e66XgI8lXc= Message-ID: <06e52c9c-9026-4279-b8c0-53a54a667dad@arm.com> Date: Mon, 9 Nov 2026 11:35:31 +0000 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 10/11] KVM: arm64: CCA: Support runtime faulting of memory To: Fuad Tabba Cc: Steven Price , kvm@vger.kernel.org, kvmarm@lists.linux.dev, 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 , linux-coco@lists.linux.dev, Ganapatrao Kulkarni , Gavin Shan , Shanker Donthineni , Alper Gun , "Aneesh Kumar K . V" , Emi Kisanuki , Vishal Annapurve , WeiLin.Chang@arm.com, Lorenzo Pieralisi References: <20261102141304.126883-1-steven.price@arm.com> <20261102141304.126883-11-steven.price@arm.com> Content-Language: en-US From: Suzuki K Poulose In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Fuad Thanks for sharing the pVM gmem details, some more questions below. On 09/11/2026 07:40, Fuad Tabba wrote: > Hi Suzuki, Steve, > > On Thu, 05 Nov 2026 17:30:16 +0000, Suzuki K Poulose > wrote: > [...] >>> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > [...] >>> @@ -1816,13 +1828,28 @@ static int gmem_abort(const struct kvm_s2_fault_desc *s2fd, >>> /* Pairs with the smp_wmb() in kvm_mmu_invalidate_end(). */ >>> smp_rmb(); >>> >>> + if (kvm_vm_is_realm(kvm)) { >>> + is_realm_private = kvm_realm_is_private_address(&kvm->arch.realm, >>> + s2fd->fault_ipa); >>> + >>> + if (is_realm_private != kvm_gmem_is_private_gfn(kvm, canonical_gfn)) { > [...] >> I am wondering there is a way to make it a bit more generic. The issue >> is, only Realm has private memory with guest_memfd for now. Don't know >> the pKVM plans for it. > > The plan is for protected pKVM VMs to be backed by guest_memfd too, > which would also hold each page's private/shared state [1]. So > kvm_arch_has_private_mem() will be true for them, and this comparison > applies as is. Only how the expected state is computed differs: for a > pVM it comes from the per-page share state rather than an IPA bit. When you say, per-page, you mean per-IPA or per "backing page" ? i.e., can pKVM do something like : kvm_ipa_is_private(kvm, ipa) ? (similar to Realm) or does it need the struct page backing the "ipa" ? > > Steve, could you gate the guest_memfd checks on > kvm_arch_has_private_mem(kvm) rather than kvm_vm_is_realm(), this one > and the memslot check you proposed for 02/11? Only the > kvm_realm_is_private_address() and realm_map_ipa() calls are > realm-specific, and they could be VM_REALM cases of a switch on > vm_flavor, as Marc asked for on the v21 memslot check [2]. The macro > would then only widen to protected VMs when pKVM's guest_memfd support Makes sense. Suzuki > lands. > > Cheers, > /fuad > > [1] https://lore.kernel.org/all/CA+EHjTz+WgXEW5RTxXf4oGeEb1Tsm5Ha4nOc4S1jBcp7jxP4+A@mail.gmail.com/ > [2] https://lore.kernel.org/all/86mrsw2jrn.wl-maz@kernel.org/