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AJvYcCXqvFXhzIOYzO7CxrcI9FSXK+IIpvuTEupuGdcbXnx/3O2PUrC0T8DJmrORK6gmyeiFowG0wH5pvQ==@kvack.org X-Gm-Message-State: AOJu0Yw1Mg4c+EqjgdadgaYUA9i1B5UQ3Y6PZEolsiOfVOrzqx8casHW juZcC1Uwq1yIJcr/F3d33YywR2bXqNAtbnThOexYZGLavRseNHvoTUdzO5/pLrpL/aziP/7cyZA fB7dxoBh8C7jxdRcF1YHyUzkdng== X-Google-Smtp-Source: AGHT+IHjj8hb/RVvZ0IOpTAd6gcfF67ZbXjAX68CTThBkFnrnLTw7dIsH6cNRpPgLu+DDO0Lal4k3FXkbzgyillaoQ== X-Received: from pffl14.prod.google.com ([2002:a62:be0e:0:b0:73e:1cf2:cd5c]) (user=ackerleytng job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:c8d:b0:740:6f69:f52a with SMTP id d2e1a72fcca58-742a9616b19mr4851938b3a.0.1747404448303; Fri, 16 May 2025 07:07:28 -0700 (PDT) Date: Fri, 16 May 2025 07:07:27 -0700 In-Reply-To: (message from Ackerley Tng on Wed, 14 May 2025 16:42:08 -0700) Mime-Version: 1.0 Message-ID: Subject: Re: [RFC PATCH v2 29/51] mm: guestmem_hugetlb: Wrap HugeTLB as an allocator for guest_memfd From: Ackerley Tng To: Ackerley Tng Cc: kvm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, linux-fsdevel@vger.kernel.org, aik@amd.com, ajones@ventanamicro.com, akpm@linux-foundation.org, amoorthy@google.com, anthony.yznaga@oracle.com, anup@brainfault.org, aou@eecs.berkeley.edu, bfoster@redhat.com, binbin.wu@linux.intel.com, brauner@kernel.org, catalin.marinas@arm.com, chao.p.peng@intel.com, chenhuacai@kernel.org, dave.hansen@intel.com, david@redhat.com, dmatlack@google.com, dwmw@amazon.co.uk, erdemaktas@google.com, fan.du@intel.com, fvdl@google.com, graf@amazon.com, haibo1.xu@intel.com, hch@infradead.org, hughd@google.com, ira.weiny@intel.com, isaku.yamahata@intel.com, jack@suse.cz, james.morse@arm.com, jarkko@kernel.org, jgg@ziepe.ca, jgowans@amazon.com, jhubbard@nvidia.com, jroedel@suse.de, jthoughton@google.com, jun.miao@intel.com, kai.huang@intel.com, keirf@google.com, kent.overstreet@linux.dev, kirill.shutemov@intel.com, liam.merwick@oracle.com, maciej.wieczor-retman@intel.com, mail@maciej.szmigiero.name, maz@kernel.org, mic@digikod.net, michael.roth@amd.com, mpe@ellerman.id.au, muchun.song@linux.dev, nikunj@amd.com, nsaenz@amazon.es, oliver.upton@linux.dev, palmer@dabbelt.com, pankaj.gupta@amd.com, paul.walmsley@sifive.com, pbonzini@redhat.com, pdurrant@amazon.co.uk, peterx@redhat.com, pgonda@google.com, pvorel@suse.cz, qperret@google.com, quic_cvanscha@quicinc.com, quic_eberman@quicinc.com, quic_mnalajal@quicinc.com, quic_pderrin@quicinc.com, quic_pheragu@quicinc.com, quic_svaddagi@quicinc.com, quic_tsoni@quicinc.com, richard.weiyang@gmail.com, rick.p.edgecombe@intel.com, rientjes@google.com, roypat@amazon.co.uk, rppt@kernel.org, seanjc@google.com, shuah@kernel.org, steven.price@arm.com, steven.sistare@oracle.com, suzuki.poulose@arm.com, tabba@google.com, thomas.lendacky@amd.com, usama.arif@bytedance.com, vannapurve@google.com, vbabka@suse.cz, viro@zeniv.linux.org.uk, vkuznets@redhat.com, wei.w.wang@intel.com, will@kernel.org, willy@infradead.org, xiaoyao.li@intel.com, yan.y.zhao@intel.com, yilun.xu@intel.com, yuzenghui@huawei.com, zhiquan1.li@intel.com Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: zx38m7jj1px66xdrq8renon5tmdeofj3 X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: AAF58140019 X-HE-Tag: 1747404449-405050 X-HE-Meta: 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 kzHs49IB 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Ackerley Tng writes: > guestmem_hugetlb is an allocator for guest_memfd. It wraps HugeTLB to > provide huge folios for guest_memfd. > > This patch also introduces guestmem_allocator_operations as a set of > operations that allocators for guest_memfd can provide. In a later > patch, guest_memfd will use these operations to manage pages from an > allocator. > > The allocator operations are memory-management specific and are placed > in mm/ so key mm-specific functions do not have to be exposed > unnecessarily. > > Signed-off-by: Ackerley Tng > > Change-Id: I3cafe111ea7b3c84755d7112ff8f8c541c11136d > --- > include/linux/guestmem.h | 20 +++++ > include/uapi/linux/guestmem.h | 29 +++++++ > mm/Kconfig | 5 +- > mm/guestmem_hugetlb.c | 159 ++++++++++++++++++++++++++++++++++ > 4 files changed, 212 insertions(+), 1 deletion(-) > create mode 100644 include/linux/guestmem.h > create mode 100644 include/uapi/linux/guestmem.h > > > > diff --git a/mm/Kconfig b/mm/Kconfig > index 131adc49f58d..bb6e39e37245 100644 > --- a/mm/Kconfig > +++ b/mm/Kconfig > @@ -1218,7 +1218,10 @@ config SECRETMEM > > config GUESTMEM_HUGETLB > bool "Enable guestmem_hugetlb allocator for guest_memfd" > - depends on HUGETLBFS > + select GUESTMEM > + select HUGETLBFS > + select HUGETLB_PAGE > + select HUGETLB_PAGE_OPTIMIZE_VMEMMAP My bad. I left out CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON=y in my testing and just found that when it is set, I hit BUG_ON(pte_page(ptep_get(pte)) != walk->reuse_page); with the basic guest_memfd_test on splitting pages on allocation. I'll follow up with the fix soon. Another note about testing: I've been testing in a nested VM for the development process: 1. Host 2. VM for development 3. Nested VM running kernel being developed 4. Nested nested VMs created during selftests This series has not yet been tested on a physical host. > help > Enable this to make HugeTLB folios available to guest_memfd > (KVM virtualization) as backing memory. > > >