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[173.79.60.52]) by smtp.gmail.com with ESMTPSA id af79cd13be357-939e190f8c3sm78248785a.17.2026.09.10.06.39.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 10 Sep 2026 06:39:26 -0700 (PDT) Date: Thu, 10 Sep 2026 09:39:24 -0400 From: Gregory Price To: "David Hildenbrand (Arm)" Cc: Ackerley Tng , linux-mm@kvack.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, pbonzini@redhat.com, seanjc@google.com, akpm@linux-foundation.org, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, ying.huang@linux.alibaba.com, apopple@nvidia.com, shuah@kernel.org Subject: Re: [PATCH 0/5] KVM: guest_memfd: bind backing memory to a NUMA node Message-ID: References: <20260902194657.79075-1-gourry@gourry.net> <0386eb30-0e0c-4d8c-abfe-86161b9e3d1f@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0386eb30-0e0c-4d8c-abfe-86161b9e3d1f@kernel.org> On Thu, Sep 10, 2026 at 01:32:08PM +0200, David Hildenbrand (Arm) wrote: > >> 3. Why not request the guest_memfd to be mmap-able just to be able to > >> set a memory policy? > > > > the eventual intent is to enable this for fully confidential, > > host-unmapped guest, isolated to a particular memory device. > > > > Requiring a mapping to get node-placement is quite defeating the point. > > You only need a VMA, not actually mapped/faulted pages. So I don't immediately > see the problem? > There is no VMA here - only an inode (GMEM_I), which is where the shared policy hangs off of. So yeah, if there was a vma, that's i suppose the missing component needed to hook up userland mempolicy to all of this - but I would have thought creating a VMA for guest_memfd is hacky and confusing (since its intent is to basically not have a VMA). Is there a series I missed that was proposing this? ~Gregory