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AJvYcCWSIifLZFZFdF2iSwmTF7GAmwphEYP2VuCg2TgAzLdpxUxgXYPPmYGrnkAYc4zyAXlSDjz2tUgCYA==@kvack.org X-Gm-Message-State: AOJu0YyWgr+edB3xJXcZdpD3IiSR0eba+Z6HvvKl4zFEyNX9pQGWmwJO 49S8CXpjENEWmPwtcF/gXlAtj4tbfbbypuPPGcrQMpzZl72p/izHoMH+h1HR1irTaLxScmn/1Q= = X-Google-Smtp-Source: AGHT+IGl0L+YQjnz7OSpay/gXAo8oxSXXskgyTEmCA9MZ9D7uSR+5ym8M6rluFfuo6rcX+QX8YfBK7dWiQ== X-Received: from wmqe11.prod.google.com ([2002:a05:600c:4e4b:b0:43d:4038:9229]) (user=tabba job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:1504:b0:43c:ed33:a500 with SMTP id 5b1f17b1804b1-43d3b9cc07fmr27713425e9.10.1742314853967; Tue, 18 Mar 2025 09:20:53 -0700 (PDT) Date: Tue, 18 Mar 2025 16:20:42 +0000 In-Reply-To: <20250318162046.4016367-1-tabba@google.com> Mime-Version: 1.0 References: <20250318162046.4016367-1-tabba@google.com> X-Mailer: git-send-email 2.49.0.rc1.451.g8f38331e32-goog Message-ID: <20250318162046.4016367-4-tabba@google.com> Subject: [PATCH v6 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, tabba@google.com X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 363A1180004 X-Stat-Signature: mdsz3djn1x9rz7f1yzankrbcouph51cb X-HE-Tag: 1742314854-154584 X-HE-Meta: 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 fwwq75KH 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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 | 56 ++++++++++++++++++++++++++++++++++++++---- 1 file changed, 51 insertions(+), 5 deletions(-) diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index ac6b8853699d..a7f7c6eb6b4a 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -17,6 +17,17 @@ struct kvm_gmem { struct list_head entry; }; +struct kvm_gmem_inode_private { +#ifdef CONFIG_KVM_GMEM_SHARED_MEM + struct xarray shared_offsets; +#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 +335,28 @@ 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 +584,7 @@ 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 +593,19 @@ 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); +#endif + + inode->i_mapping->i_private_data = private; inode->i_private = (void *)(unsigned long)flags; inode->i_op = &kvm_gmem_iops; @@ -577,6 +618,11 @@ 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,