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AJvYcCV2i5n0uQK2CPGx9KsnxMFUmZA9zJKpzSEHfq7+R7cz32r+SPHsoxqZnA4N+xGBkypz8Xx+0JQNca4xoKba@vger.kernel.org X-Gm-Message-State: AOJu0YzqMG6+INL5YavBxD/7xhLnmQs0brQSPkR4BBUcdvj4BJmmYR23 K2F+sD4f7ZLtxMPFpflnbOMLOjQAkJF38nebb09qsBpNOzLgMzHWr1SccbU4NOYURgx7HUlKod5 oCeZrNVLQJa/riXrL9b4YZg== X-Google-Smtp-Source: AGHT+IGyLkn3nqeNKfrPwmXh8d7PdkrS0NNj4rvg8/rg8+lUUn5fqkFx2CkNgkz2N4cDBWoYAECpFAIq4YtOUG++oA== X-Received: from pjbsy6.prod.google.com ([2002:a17:90b:2d06:b0:2e0:915d:d594]) (user=ackerleytng job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:38cc:b0:2ff:5ec1:6c6a with SMTP id 98e67ed59e1d1-30e2e5dcdcamr9260937a91.18.1747266239615; Wed, 14 May 2025 16:43:59 -0700 (PDT) Date: Wed, 14 May 2025 16:42:19 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: X-Mailer: git-send-email 2.49.0.1045.g170613ef41-goog Message-ID: <3f48795c0c34f4faf661394e5ad9805f9014ae23.1747264138.git.ackerleytng@google.com> Subject: [RFC PATCH v2 40/51] KVM: guest_memfd: Update kvm_gmem_mapping_order to account for page status From: Ackerley Tng To: kvm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, linux-fsdevel@vger.kernel.org Cc: ackerleytng@google.com, 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" kvm_gmem_mapping_order() should return the maximum mapping order for a gfn if a page were to be faulted in for that gfn. For inodes that support a custom allocator, the maximum mapping order should be determined by the custom allocator in conjunction with guest_memfd. This patch updates kvm_gmem_mapping_order() to take into account that for the guestmem_hugetlb custom allocator, pages are split if any page in a huge page range is shared. Change-Id: I5c061af6cefdcbd708a4334cd58edc340afcf44e Signed-off-by: Ackerley Tng --- virt/kvm/guest_memfd.c | 72 ++++++++++++++++++++++++++++++++++++------ 1 file changed, 62 insertions(+), 10 deletions(-) diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index 04b1513c2998..8b5fe1360e58 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -709,19 +709,27 @@ static int kvm_gmem_split_folio_in_filemap(struct inode *inode, struct folio *fo return ret; } +static inline bool kvm_gmem_should_split_at_index(struct inode *inode, + pgoff_t index) +{ + pgoff_t index_floor; + size_t nr_pages; + void *priv; + + priv = kvm_gmem_allocator_private(inode); + nr_pages = kvm_gmem_allocator_ops(inode)->nr_pages_in_folio(priv); + index_floor = round_down(index, nr_pages); + + return kvm_gmem_has_some_shared(inode, index_floor, nr_pages); +} + static inline int kvm_gmem_try_split_folio_in_filemap(struct inode *inode, struct folio *folio) { - size_t to_nr_pages; - void *priv; - if (!kvm_gmem_has_custom_allocator(inode)) return 0; - priv = kvm_gmem_allocator_private(inode); - to_nr_pages = kvm_gmem_allocator_ops(inode)->nr_pages_in_page(priv); - - if (kvm_gmem_has_some_shared(inode, folio->index, to_nr_pages)) + if (kvm_gmem_should_split_at_index(inode, folio->index)) return kvm_gmem_split_folio_in_filemap(inode, folio); return 0; @@ -890,6 +898,12 @@ static long kvm_gmem_merge_truncate_indices(struct inode *inode, pgoff_t index, #else +static inline bool kvm_gmem_should_split_at_index(struct inode *inode, + pgoff_t index) +{ + return false; +} + static inline int kvm_gmem_try_split_folio_in_filemap(struct inode *inode, struct folio *folio) { @@ -1523,7 +1537,7 @@ static inline struct file *kvm_gmem_get_file(struct kvm_memory_slot *slot) return get_file_active(&slot->gmem.file); } -static pgoff_t kvm_gmem_get_index(struct kvm_memory_slot *slot, gfn_t gfn) +static pgoff_t kvm_gmem_get_index(const struct kvm_memory_slot *slot, gfn_t gfn) { return gfn - slot->base_gfn + slot->gmem.pgoff; } @@ -2256,14 +2270,52 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot, EXPORT_SYMBOL_GPL(kvm_gmem_get_pfn); /** - * Returns the mapping order for this @gfn in @slot. + * kvm_gmem_mapping_order() - Get the mapping order for this @gfn in @slot. + * + * @slot: the memslot that gfn belongs to. + * @gfn: the gfn to look up mapping order for. * * This is equal to max_order that would be returned if kvm_gmem_get_pfn() were * called now. + * + * Return: the mapping order for this @gfn in @slot. */ int kvm_gmem_mapping_order(const struct kvm_memory_slot *slot, gfn_t gfn) { - return 0; + struct inode *inode; + struct file *file; + int ret; + + file = kvm_gmem_get_file((struct kvm_memory_slot *)slot); + if (!file) + return 0; + + inode = file_inode(file); + + ret = 0; + if (kvm_gmem_has_custom_allocator(inode)) { + bool should_split; + pgoff_t index; + + index = kvm_gmem_get_index(slot, gfn); + + filemap_invalidate_lock_shared(inode->i_mapping); + should_split = kvm_gmem_should_split_at_index(inode, index); + filemap_invalidate_unlock_shared(inode->i_mapping); + + if (!should_split) { + size_t nr_pages; + void *priv; + + priv = kvm_gmem_allocator_private(inode); + nr_pages = kvm_gmem_allocator_ops(inode)->nr_pages_in_folio(priv); + + ret = ilog2(nr_pages); + } + } + + fput(file); + return ret; } EXPORT_SYMBOL_GPL(kvm_gmem_mapping_order); -- 2.49.0.1045.g170613ef41-goog