From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 02CB017BEBF; Wed, 23 Jul 2025 08:20:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753258853; cv=none; b=j04cWt1O7jpAqK/VdFztCkqzcPPPRYU1EG++IWfyv41vkWEXaa+aFLuMRoAIHi9di0o5M11A5pjMDtMFYQJqW6Hz2xM+/sn2m+cvUf0lgjyyg3Tm6E2N9+MpNIFhTZlYWIccWYcbBchDq5x9k2mmYYuw9eRY+OwUOLVZYzsRmnI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753258853; c=relaxed/simple; bh=Xsw3QoZiMPB8j16P6Zigy/0n3Pl6zL7Tf5S+EO6pdSc=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=dZJPfapD25U4XiMHFQcCrnFFhe/KP1tAcvPH7r0KLFkLe+odzKlPiTMPjAP8leLjd8ySPi0eBalVYXsGkgd1PtK/sA+SyJA64imvHvK6yJdOvEIr+h5JnnSZ0NBXBBhGC8EMjD61gB9gjfA08xqyCPDhCgdKrL6AKI8Ea+w7v5Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=IMvdhjIV; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="IMvdhjIV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 68972C4CEE7; Wed, 23 Jul 2025 08:20:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1753258852; bh=Xsw3QoZiMPB8j16P6Zigy/0n3Pl6zL7Tf5S+EO6pdSc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=IMvdhjIVoTWOkOkifH69KUZdMExh3V0toaYm4XhvU5rQbUnqJ2W4/K9ljJhPpvAsJ vBFe7YZ7c6P90+WqFyAIQ35nBaxBfCMVfRbvZKe0RXzK4Pg8puy92WGPjZw1q2nHM4 9p75I7HG1gZbDDrJGAwzy3lkgZcX5A9aPQ+yzory8QnE3mx4OJnwYOzkIbYUUjCxG9 nABfhefve/uAggH7xD+fSFwbUUt3jyv6kbu13WY6dI/T2xfzpEiNCkAck5WNIWDK7t Ka4dWmv1gbJ5l/O0T8xz0hWbbZ5+BUREZl3UkbF1mM0CemYFKhUhQqrSQPcjIdoSln rlQCXtwYFzblw== Received: from 82-132-236-66.dab.02.net ([82.132.236.66] helo=lobster-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1ueUiX-000bju-0K; Wed, 23 Jul 2025 09:20:49 +0100 Date: Wed, 23 Jul 2025 09:20:35 +0100 Message-ID: <87pldrtj1o.wl-maz@kernel.org> From: Marc Zyngier To: Kunwu Chan Cc: Fuad Tabba , kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org, kvmarm@lists.linux.dev, pbonzini@redhat.com, chenhuacai@kernel.org, mpe@ellerman.id.au, anup@brainfault.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, seanjc@google.com, viro@zeniv.linux.org.uk, brauner@kernel.org, willy@infradead.org, akpm@linux-foundation.org, xiaoyao.li@intel.com, yilun.xu@intel.com, chao.p.peng@linux.intel.com, jarkko@kernel.org, amoorthy@google.com, dmatlack@google.com, isaku.yamahata@intel.com, mic@digikod.net, vbabka@suse.cz, vannapurve@google.com, ackerleytng@google.com, mail@maciej.szmigiero.name, david@redhat.com, michael.roth@amd.com, wei.w.wang@intel.com, liam.merwick@oracle.com, isaku.yamahata@gmail.com, kirill.shutemov@linux.intel.com, suzuki.poulose@arm.com, steven.price@arm.com, quic_eberman@quicinc.com, quic_mnalajal@quicinc.com, quic_tsoni@quicinc.com, quic_svaddagi@quicinc.com, quic_cvanscha@quicinc.com, quic_pderrin@quicinc.com, quic_pheragu@quicinc.com, catalin.marinas@arm.com, james.morse@arm.com, yuzenghui@huawei.com, oliver.upton@linux.dev, will@kernel.org, qperret@google.com, keirf@google.com, roypat@amazon.co.uk, shuah@kernel.org, hch@infradead.org, jgg@nvidia.com, rientjes@google.com, jhubbard@nvidia.com, fvdl@google.com, hughd@google.com, jthoughton@google.com, peterx@redhat.com, pankaj.gupta@amd.com, ira.weiny@intel.com Subject: Re: [PATCH v15 16/21] KVM: arm64: Handle guest_memfd-backed guest page faults In-Reply-To: <07976427-e5a4-4ca4-93e9-a428a962b0b2@linux.dev> References: <20250717162731.446579-1-tabba@google.com> <20250717162731.446579-17-tabba@google.com> <07976427-e5a4-4ca4-93e9-a428a962b0b2@linux.dev> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-SA-Exim-Connect-IP: 82.132.236.66 X-SA-Exim-Rcpt-To: kunwu.chan@linux.dev, tabba@google.com, kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org, kvmarm@lists.linux.dev, pbonzini@redhat.com, chenhuacai@kernel.org, mpe@ellerman.id.au, anup@brainfault.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, seanjc@google.com, viro@zeniv.linux.org.uk, brauner@kernel.org, willy@infradead.org, akpm@linux-foundation.org, xiaoyao.li@intel.com, yilun.xu@intel.com, chao.p.peng@linux.intel.com, jarkko@kernel.org, amoorthy@google.com, dmatlack@google.com, isaku.yamahata@intel.com, mic@digikod.net, vbabka@suse.cz, vannapurve@google.com, ackerleytng@google.com, mail@maciej.szmigiero.name, david@redhat.com, michael.roth@amd.com, wei.w.wang@intel.com, liam.merwick@oracle.com, isaku.yamahata@gmail.com, kirill.shutemov@linux.intel.com, suzuki.poulose@arm.com, steven.price@arm.com, quic_eberman@quicinc.com, quic_mnalajal@quicinc.com, quic_tsoni@quicinc.com, quic_svaddagi@quicinc.com, quic_cvanscha@quicinc.com, quic_pderrin@quicinc.com, quic_pheragu@quicinc.com, catalin.marinas@arm.com, james.morse@arm.com, yuzenghui@huawei.com, oliver.upton@linux.dev, will@kernel.org, qperret@google.com, keirf@google.com, roypat@amazon.co.uk, shuah@kernel.org, hch@infradead.org, jgg@nvidia.com, rientjes@google.com, jhubbard@nvidia.com, fvdl@google.com, hughd@google.com, jthoughton@google.com, peterx@redhat.com, pankaj.gupta@amd.com, ira.weiny@intel.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Tue, 22 Jul 2025 13:31:34 +0100, Kunwu Chan wrote: >=20 > On 2025/7/18 00:27, Fuad Tabba wrote: > > Add arm64 architecture support for handling guest page faults on memory > > slots backed by guest_memfd. > >=20 > > This change introduces a new function, gmem_abort(), which encapsulates > > the fault handling logic specific to guest_memfd-backed memory. The > > kvm_handle_guest_abort() entry point is updated to dispatch to > > gmem_abort() when a fault occurs on a guest_memfd-backed memory slot (as > > determined by kvm_slot_has_gmem()). > >=20 > > Until guest_memfd gains support for huge pages, the fault granule for > > these memory regions is restricted to PAGE_SIZE. >=20 > Since huge pages are not currently supported, would it be more > friendly to define=C2=A0 sth like >=20 > "#define GMEM_PAGE_GRANULE PAGE_SIZE" at the top (rather than > hardcoding PAGE_SIZE) >=20 > =C2=A0and make it easier to switch to huge page support later? No. PAGE_SIZE always has to be the fallback, no matter what. When (and if) larger mappings get supported, there will be extra code for that purpose, not just flipping a definition. Thanks, M. --=20 Jazz isn't dead. It just smells funny.