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X-CSE-ConnectionGUID: B1oPw1IjR1G8AgK37+1MRw== X-CSE-MsgGUID: NACSQGsASGujHisr4Sy4dg== X-IronPort-AV: E=McAfee;i="6800,10657,11495"; a="54977948" X-IronPort-AV: E=Sophos;i="6.16,320,1744095600"; d="scan'208";a="54977948" Received: from orviesa006.jf.intel.com ([10.64.159.146]) by orvoesa113.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Jul 2025 19:57:06 -0700 X-CSE-ConnectionGUID: 4aAcsyaETE28nvuGRlN+zw== X-CSE-MsgGUID: BbAsaMudTLW2zflXrSC6Ng== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.16,320,1744095600"; d="scan'208";a="157340783" Received: from xiaoyaol-hp-g830.ccr.corp.intel.com (HELO [10.124.247.1]) ([10.124.247.1]) by orviesa006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Jul 2025 19:56:52 -0700 Message-ID: Date: Fri, 18 Jul 2025 10:56:49 +0800 Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v15 08/21] KVM: guest_memfd: Allow host to map guest_memfd pages To: Fuad Tabba , kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org, kvmarm@lists.linux.dev Cc: 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, 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, maz@kernel.org, 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 References: <20250717162731.446579-1-tabba@google.com> <20250717162731.446579-9-tabba@google.com> Content-Language: en-US From: Xiaoyao Li In-Reply-To: <20250717162731.446579-9-tabba@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 7/18/2025 12:27 AM, Fuad Tabba wrote: > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 1ec71648824c..9ac21985f3b5 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -740,6 +740,19 @@ static inline bool kvm_arch_supports_gmem(struct kvm *kvm) > } > #endif > > +/* > + * Returns true if this VM supports mmap() in guest_memfd. > + * > + * Arch code must define kvm_arch_supports_gmem_mmap if support for guest_memfd > + * is enabled. > + */ > +#if !defined(kvm_arch_supports_gmem_mmap) Unless being given a reason or you change it to #if !defined(kvm_arch_supports_gmem_mmap) && !IS_ENABLED(CONFIG_KVM_GMEM) I will repeat my opinion as what on v14[*] * It describes the similar requirement as kvm_arch_has_private_mem and * kvm_arch_supports_gmem, but it doesn't have the check of * * && !IS_ENABLED(CONFIG_KVM_GMEM) * * So it's straightforward for people to wonder why. * * I would suggest just adding the check of !IS_ENABLED(CONFIG_KVM_GMEM) * like what for kvm_arch_has_private_mem and kvm_arch_supports_gmem. * So it will get compilation error if any ARCH enables CONFIG_KVM_GMEM * without defining kvm_arch_supports_gmem_mmap. [*] https://lore.kernel.org/all/e1470c54-fe2b-4fdf-9b4b-ce9ef0d04a1b@intel.com/ > +static inline bool kvm_arch_supports_gmem_mmap(struct kvm *kvm) > +{ > + return false; > +} > +#endif > +