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X-CSE-ConnectionGUID: sjFHB1X7QMC5nAeHjAn/Lw== X-CSE-MsgGUID: d3sHGIWfShGmkJ7kGFwNAg== X-IronPort-AV: E=McAfee;i="6800,10657,11493"; a="54947365" X-IronPort-AV: E=Sophos;i="6.16,318,1744095600"; d="scan'208";a="54947365" Received: from fmviesa008.fm.intel.com ([10.60.135.148]) by fmvoesa111.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Jul 2025 02:00:20 -0700 X-CSE-ConnectionGUID: grRhNT59TOae6QFdno4wGg== X-CSE-MsgGUID: /gOPa19PR0iPIjZ0z+7J7A== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.16,318,1744095600"; d="scan'208";a="158292638" Received: from xiaoyaol-hp-g830.ccr.corp.intel.com (HELO [10.124.247.1]) ([10.124.247.1]) by fmviesa008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Jul 2025 02:00:06 -0700 Message-ID: Date: Thu, 17 Jul 2025 17:00:03 +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 v14 04/21] KVM: x86: Introduce kvm->arch.supports_gmem To: Fuad Tabba Cc: Ackerley Tng , 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, 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, 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: <20250715093350.2584932-1-tabba@google.com> <20250715093350.2584932-5-tabba@google.com> Content-Language: en-US From: Xiaoyao Li In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 7/17/2025 4:49 PM, Fuad Tabba wrote: > On Thu, 17 Jul 2025 at 02:48, Xiaoyao Li wrote: >> On 7/17/2025 8:12 AM, Ackerley Tng wrote: >>> Xiaoyao Li writes: >>> ... >>>> >>>> Btw, it seems that supports_gmem can be enabled for all the types of VM? >>>> >>> For now, not really, because supports_gmem allows mmap support, and mmap >>> support enables KVM_MEMSLOT_GMEM_ONLY, and KVM_MEMSLOT_GMEM_ONLY will >>> mean that shared faults also get faulted from guest_memfd. >> No, mmap support is checked by kvm_arch_supports_gmem_mmap() which is >> independent to whether gmem is supported. > It is dependent on gmem support: > > kvm_arch_supports_gmem_mmap(kvm) depends on > CONFIG_KVM_GMEM_SUPPORTS_MMAP, which in turn selects KVM_GMEM. My bad that my words leads to misunderstanding. What I wanted to express it that support_gmem doesn't mean mmap support is allowed, there is additional specific guard for mmap support via kvm_arch_supports_gmem_mmap().