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AJvYcCVFTxnrXpP5sWBDUG5FTxgJKWHV4HWhTlDcBHx2VzwiAkU5ha3XX/FVjo9rPFq5D0ZPgI/VI59oGg==@kvack.org X-Gm-Message-State: AOJu0Yz57BBDtJXPphQ2uZy75IKBYC2LVzqNRII9OurXI3UkfhqyU7b2 kcTlh83CnJca9Wa+PcyAPLPSbJUPCyD5PB9nDMOD+qTWm4Z8cb9NPsTdY/zvZyjLbTs4lHUU5A= = X-Google-Smtp-Source: AGHT+IEcG7Zl1YWubAQ/xxzfCc7DzPo7o1l3NxQG19us3iyaCBZ3hbODn54f9bMZd/gVjGPshQUZSrIV3Q== X-Received: from wmsp31.prod.google.com ([2002:a05:600c:1d9f:b0:43d:1f62:f36c]) (user=tabba job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:45c8:b0:43c:fdbe:439b with SMTP id 5b1f17b1804b1-43d84f5de84mr98366605e9.4.1743175900745; Fri, 28 Mar 2025 08:31:40 -0700 (PDT) Date: Fri, 28 Mar 2025 15:31:29 +0000 In-Reply-To: <20250328153133.3504118-1-tabba@google.com> Mime-Version: 1.0 References: <20250328153133.3504118-1-tabba@google.com> X-Mailer: git-send-email 2.49.0.472.ge94155a9ec-goog Message-ID: <20250328153133.3504118-4-tabba@google.com> Subject: [PATCH v7 3/7] KVM: guest_memfd: Track folio sharing within a struct kvm_gmem_private From: Fuad Tabba To: kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org 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, xiaoyao.li@intel.com, 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, tabba@google.com X-Rspamd-Queue-Id: 056C3A0008 X-Stat-Signature: gdmxknd1okp83odacczkbs7f585aa5wy X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1743175901-802268 X-HE-Meta: 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 HDCUwJxu 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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: From: Ackerley Tng Track guest_memfd folio sharing state within the inode, since it is a property of the guest_memfd's memory contents. The guest_memfd PRIVATE memory attribute is not used for two reasons. It reflects the userspace expectation for the memory state, and therefore can be toggled by userspace. Also, although each guest_memfd file has a 1:1 binding with a KVM instance, the plan is to allow multiple files per inode, e.g. to allow intra-host migration to a new KVM instance, without destroying guest_memfd. Signed-off-by: Ackerley Tng Co-developed-by: Vishal Annapurve Signed-off-by: Vishal Annapurve Co-developed-by: Fuad Tabba Signed-off-by: Fuad Tabba --- virt/kvm/guest_memfd.c | 58 ++++++++++++++++++++++++++++++++++++++---- 1 file changed, 53 insertions(+), 5 deletions(-) diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index ac6b8853699d..cde16ed3b230 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -17,6 +17,18 @@ struct kvm_gmem { struct list_head entry; }; +struct kvm_gmem_inode_private { +#ifdef CONFIG_KVM_GMEM_SHARED_MEM + struct xarray shared_offsets; + rwlock_t offsets_lock; +#endif +}; + +static struct kvm_gmem_inode_private *kvm_gmem_private(struct inode *inode) +{ + return inode->i_mapping->i_private_data; +} + #ifdef CONFIG_KVM_GMEM_SHARED_MEM void kvm_gmem_handle_folio_put(struct folio *folio) { @@ -324,8 +336,28 @@ static pgoff_t kvm_gmem_get_index(struct kvm_memory_slot *slot, gfn_t gfn) return gfn - slot->base_gfn + slot->gmem.pgoff; } +static void kvm_gmem_evict_inode(struct inode *inode) +{ + struct kvm_gmem_inode_private *private = kvm_gmem_private(inode); + +#ifdef CONFIG_KVM_GMEM_SHARED_MEM + /* + * .evict_inode can be called before private data is set up if there are + * issues during inode creation. + */ + if (private) + xa_destroy(&private->shared_offsets); +#endif + + truncate_inode_pages_final(inode->i_mapping); + + kfree(private); + clear_inode(inode); +} + static const struct super_operations kvm_gmem_super_operations = { - .statfs = simple_statfs, + .statfs = simple_statfs, + .evict_inode = kvm_gmem_evict_inode, }; static int kvm_gmem_init_fs_context(struct fs_context *fc) @@ -553,6 +585,7 @@ static struct inode *kvm_gmem_inode_make_secure_inode(const char *name, loff_t size, u64 flags) { const struct qstr qname = QSTR_INIT(name, strlen(name)); + struct kvm_gmem_inode_private *private; struct inode *inode; int err; @@ -561,10 +594,20 @@ static struct inode *kvm_gmem_inode_make_secure_inode(const char *name, return inode; err = security_inode_init_security_anon(inode, &qname, NULL); - if (err) { - iput(inode); - return ERR_PTR(err); - } + if (err) + goto out; + + err = -ENOMEM; + private = kzalloc(sizeof(*private), GFP_KERNEL); + if (!private) + goto out; + +#ifdef CONFIG_KVM_GMEM_SHARED_MEM + xa_init(&private->shared_offsets); + rwlock_init(&private->offsets_lock); +#endif + + inode->i_mapping->i_private_data = private; inode->i_private = (void *)(unsigned long)flags; inode->i_op = &kvm_gmem_iops; @@ -577,6 +620,11 @@ static struct inode *kvm_gmem_inode_make_secure_inode(const char *name, WARN_ON_ONCE(!mapping_unevictable(inode->i_mapping)); return inode; + +out: + iput(inode); + + return ERR_PTR(err); } static struct file *kvm_gmem_inode_create_getfile(void *priv, loff_t size,