From: Sean Christopherson <seanjc@google.com>
To: Xu Yilun <yilun.xu@linux.intel.com>
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
"Marc Zyngier" <maz@kernel.org>,
"Oliver Upton" <oliver.upton@linux.dev>,
"Huacai Chen" <chenhuacai@kernel.org>,
"Michael Ellerman" <mpe@ellerman.id.au>,
"Anup Patel" <anup@brainfault.org>,
"Paul Walmsley" <paul.walmsley@sifive.com>,
"Palmer Dabbelt" <palmer@dabbelt.com>,
"Albert Ou" <aou@eecs.berkeley.edu>,
"Alexander Viro" <viro@zeniv.linux.org.uk>,
"Christian Brauner" <brauner@kernel.org>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
kvmarm@lists.linux.dev, linux-mips@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org,
linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
"Xiaoyao Li" <xiaoyao.li@intel.com>,
"Xu Yilun" <yilun.xu@intel.com>,
"Chao Peng" <chao.p.peng@linux.intel.com>,
"Fuad Tabba" <tabba@google.com>,
"Jarkko Sakkinen" <jarkko@kernel.org>,
"Anish Moorthy" <amoorthy@google.com>,
"David Matlack" <dmatlack@google.com>,
"Yu Zhang" <yu.c.zhang@linux.intel.com>,
"Isaku Yamahata" <isaku.yamahata@intel.com>,
"Mickaël Salaün" <mic@digikod.net>,
"Vlastimil Babka" <vbabka@suse.cz>,
"Vishal Annapurve" <vannapurve@google.com>,
"Ackerley Tng" <ackerleytng@google.com>,
"Maciej Szmigiero" <mail@maciej.szmigiero.name>,
"David Hildenbrand" <david@redhat.com>,
"Quentin Perret" <qperret@google.com>,
"Michael Roth" <michael.roth@amd.com>,
Wang <wei.w.wang@intel.com>,
"Liam Merwick" <liam.merwick@oracle.com>,
"Isaku Yamahata" <isaku.yamahata@gmail.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH v13 16/35] KVM: Add KVM_CREATE_GUEST_MEMFD ioctl() for guest-specific backing memory
Date: Mon, 6 Nov 2023 07:43:07 -0800 [thread overview]
Message-ID: <ZUkJiwp8VHY0ICab@google.com> (raw)
In-Reply-To: <ZUYcb6no9ADYytrx@yilunxu-OptiPlex-7050>
On Sat, Nov 04, 2023, Xu Yilun wrote:
> > +KVM_SET_USER_MEMORY_REGION2 is an extension to KVM_SET_USER_MEMORY_REGION that
> > +allows mapping guest_memfd memory into a guest. All fields shared with
> > +KVM_SET_USER_MEMORY_REGION identically. Userspace can set KVM_MEM_PRIVATE in
> > +flags to have KVM bind the memory region to a given guest_memfd range of
> > +[guest_memfd_offset, guest_memfd_offset + memory_size]. The target guest_memfd
> ^
> The range end should be exclusive, is it?
Yes, that should be a ')', not a ']'.
> > +static int __kvm_gmem_create(struct kvm *kvm, loff_t size, u64 flags)
> > +{
> > + const char *anon_name = "[kvm-gmem]";
> > + struct kvm_gmem *gmem;
> > + struct inode *inode;
> > + struct file *file;
> > + int fd, err;
> > +
> > + fd = get_unused_fd_flags(0);
> > + if (fd < 0)
> > + return fd;
> > +
> > + gmem = kzalloc(sizeof(*gmem), GFP_KERNEL);
> > + if (!gmem) {
> > + err = -ENOMEM;
> > + goto err_fd;
> > + }
> > +
> > + /*
> > + * Use the so called "secure" variant, which creates a unique inode
> > + * instead of reusing a single inode. Each guest_memfd instance needs
> > + * its own inode to track the size, flags, etc.
> > + */
> > + file = anon_inode_getfile_secure(anon_name, &kvm_gmem_fops, gmem,
> > + O_RDWR, NULL);
> > + if (IS_ERR(file)) {
> > + err = PTR_ERR(file);
> > + goto err_gmem;
> > + }
> > +
> > + file->f_flags |= O_LARGEFILE;
> > +
> > + inode = file->f_inode;
> > + WARN_ON(file->f_mapping != inode->i_mapping);
>
> Just curious, why should we check the mapping fields which is garanteed in
> other subsystem?
Mostly to document the behavior. The vast majority of folks that read this code
will be KVM developers, not file systems developers, and will likely have no clue
about the relationship between f_mapping and i_mapping. And in the extremely
unlikely scenario that anon_inode_getfile_secure() no longer sets f_mapping, a
WARN detects the issue whereas a comment does not.
next prev parent reply other threads:[~2023-11-06 15:43 UTC|newest]
Thread overview: 148+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-27 18:21 [PATCH v13 00/35] KVM: guest_memfd() and per-page attributes Sean Christopherson
2023-10-27 18:21 ` [PATCH v13 01/35] KVM: Tweak kvm_hva_range and hva_handler_t to allow reusing for gfn ranges Sean Christopherson
2023-11-01 12:46 ` Fuad Tabba
2023-10-27 18:21 ` [PATCH v13 02/35] KVM: Assert that mmu_invalidate_in_progress *never* goes negative Sean Christopherson
2023-10-30 16:27 ` Paolo Bonzini
2023-11-01 12:46 ` Fuad Tabba
2023-10-27 18:21 ` [PATCH v13 03/35] KVM: Use gfn instead of hva for mmu_notifier_retry Sean Christopherson
2023-10-30 16:30 ` Paolo Bonzini
2023-10-30 16:53 ` David Matlack
2023-10-30 17:00 ` Paolo Bonzini
2023-10-30 18:21 ` David Matlack
2023-10-30 18:19 ` David Matlack
2023-11-01 15:31 ` Xu Yilun
2023-10-27 18:21 ` [PATCH v13 04/35] KVM: WARN if there are dangling MMU invalidations at VM destruction Sean Christopherson
2023-10-30 16:32 ` Paolo Bonzini
2023-11-01 12:50 ` Fuad Tabba
2023-10-27 18:21 ` [PATCH v13 05/35] KVM: PPC: Drop dead code related to KVM_ARCH_WANT_MMU_NOTIFIER Sean Christopherson
2023-10-30 16:34 ` Paolo Bonzini
2023-11-01 12:51 ` Fuad Tabba
2023-10-27 18:21 ` [PATCH v13 06/35] KVM: PPC: Return '1' unconditionally for KVM_CAP_SYNC_MMU Sean Christopherson
2023-10-27 18:21 ` [PATCH v13 07/35] KVM: Convert KVM_ARCH_WANT_MMU_NOTIFIER to CONFIG_KVM_GENERIC_MMU_NOTIFIER Sean Christopherson
2023-10-30 16:37 ` Paolo Bonzini
2023-11-01 12:54 ` Fuad Tabba
2023-10-27 18:21 ` [PATCH v13 08/35] KVM: Introduce KVM_SET_USER_MEMORY_REGION2 Sean Christopherson
2023-10-30 16:41 ` Paolo Bonzini
2023-10-30 20:25 ` Sean Christopherson
2023-10-30 22:12 ` Sean Christopherson
2023-10-30 23:22 ` Paolo Bonzini
2023-10-31 0:18 ` Sean Christopherson
2023-10-31 2:26 ` Xiaoyao Li
2023-10-31 14:04 ` Sean Christopherson
2023-11-01 14:19 ` Fuad Tabba
2023-10-27 18:21 ` [PATCH v13 09/35] KVM: Add KVM_EXIT_MEMORY_FAULT exit to report faults to userspace Sean Christopherson
2023-10-30 17:22 ` Paolo Bonzini
2023-11-01 7:30 ` Binbin Wu
2023-11-01 10:52 ` Huang, Kai
2023-11-01 17:36 ` Sean Christopherson
2023-11-02 2:19 ` Xiaoyao Li
2023-11-02 15:51 ` Sean Christopherson
2023-11-02 3:17 ` Huang, Kai
2023-11-02 9:35 ` Huang, Kai
2023-11-02 11:03 ` Paolo Bonzini
2023-11-02 15:44 ` Sean Christopherson
2023-11-02 18:35 ` Huang, Kai
2023-11-02 15:56 ` Sean Christopherson
2023-11-02 11:01 ` Paolo Bonzini
2023-11-03 4:09 ` Xu Yilun
2023-10-27 18:21 ` [PATCH v13 10/35] KVM: Add a dedicated mmu_notifier flag for reclaiming freed memory Sean Christopherson
2023-10-30 17:11 ` Paolo Bonzini
2023-11-02 13:55 ` Fuad Tabba
2023-10-27 18:21 ` [PATCH v13 11/35] KVM: Drop .on_unlock() mmu_notifier hook Sean Christopherson
2023-10-30 17:18 ` Paolo Bonzini
2023-11-02 13:55 ` Fuad Tabba
2023-10-27 18:21 ` [PATCH v13 12/35] KVM: Prepare for handling only shared mappings in mmu_notifier events Sean Christopherson
2023-10-30 17:21 ` Paolo Bonzini
2023-10-30 22:07 ` Sean Christopherson
2023-11-02 5:59 ` Binbin Wu
2023-11-02 11:14 ` Paolo Bonzini
2023-11-02 14:01 ` Fuad Tabba
2023-11-02 14:41 ` Sean Christopherson
2023-11-02 14:57 ` Fuad Tabba
2023-10-27 18:21 ` [PATCH v13 13/35] KVM: Introduce per-page memory attributes Sean Christopherson
2023-10-30 8:11 ` Chao Gao
2023-10-30 16:10 ` Sean Christopherson
2023-10-30 22:05 ` Sean Christopherson
2023-10-31 16:43 ` David Matlack
2023-11-02 3:01 ` Huang, Kai
2023-11-02 10:32 ` Paolo Bonzini
2023-11-02 10:55 ` Huang, Kai
2023-10-27 18:21 ` [PATCH v13 14/35] mm: Add AS_UNMOVABLE to mark mapping as completely unmovable Sean Christopherson
2023-10-30 17:24 ` Paolo Bonzini
2023-10-27 18:21 ` [PATCH v13 15/35] fs: Export anon_inode_getfile_secure() for use by KVM Sean Christopherson
2023-10-30 17:30 ` Paolo Bonzini
2023-11-02 16:24 ` Christian Brauner
2023-11-03 10:40 ` Paolo Bonzini
2023-10-27 18:21 ` [PATCH v13 16/35] KVM: Add KVM_CREATE_GUEST_MEMFD ioctl() for guest-specific backing memory Sean Christopherson
2023-10-31 2:27 ` Xiaoyao Li
2023-10-31 6:30 ` Chao Gao
2023-10-31 14:10 ` Sean Christopherson
2023-10-31 15:05 ` Fuad Tabba
2023-10-31 22:13 ` Sean Christopherson
2023-10-31 22:18 ` Paolo Bonzini
2023-11-01 10:51 ` Fuad Tabba
2023-11-01 21:55 ` Sean Christopherson
2023-11-02 13:52 ` Fuad Tabba
2023-11-03 23:17 ` Sean Christopherson
2023-10-31 18:24 ` David Matlack
2023-10-31 21:36 ` Sean Christopherson
2023-10-31 22:39 ` David Matlack
2023-11-02 15:48 ` Paolo Bonzini
2023-11-02 16:03 ` Sean Christopherson
2023-11-02 16:28 ` David Matlack
2023-11-02 17:37 ` Sean Christopherson
2023-11-03 9:42 ` Fuad Tabba
2023-11-04 10:26 ` Xu Yilun
2023-11-06 15:43 ` Sean Christopherson [this message]
2023-10-27 18:21 ` [PATCH v13 17/35] KVM: Add transparent hugepage support for dedicated guest memory Sean Christopherson
2023-10-31 8:35 ` Xiaoyao Li
2023-10-31 14:16 ` Sean Christopherson
2023-11-01 7:25 ` Xiaoyao Li
2023-11-01 13:41 ` Sean Christopherson
2023-11-01 13:49 ` Paolo Bonzini
2023-11-01 16:36 ` Sean Christopherson
2023-11-01 22:28 ` Paolo Bonzini
2023-11-01 22:34 ` Sean Christopherson
2023-11-01 23:17 ` Paolo Bonzini
2023-11-02 15:38 ` Sean Christopherson
2023-11-02 15:46 ` Paolo Bonzini
2023-11-27 11:13 ` Vlastimil Babka
2023-11-29 22:40 ` Sean Christopherson
2023-10-27 18:22 ` [PATCH v13 18/35] KVM: x86: "Reset" vcpu->run->exit_reason early in KVM_RUN Sean Christopherson
2023-10-30 17:31 ` Paolo Bonzini
2023-11-02 14:16 ` Fuad Tabba
2023-10-27 18:22 ` [PATCH v13 19/35] KVM: x86: Disallow hugepages when memory attributes are mixed Sean Christopherson
2023-10-27 18:22 ` [PATCH v13 20/35] KVM: x86/mmu: Handle page fault for private memory Sean Christopherson
2023-11-02 14:34 ` Fuad Tabba
2023-11-05 13:02 ` Xu Yilun
2023-11-05 16:19 ` Paolo Bonzini
2023-11-06 13:29 ` Xu Yilun
2023-11-06 15:56 ` Sean Christopherson
2023-10-27 18:22 ` [PATCH v13 21/35] KVM: Drop superfluous __KVM_VCPU_MULTIPLE_ADDRESS_SPACE macro Sean Christopherson
2023-11-02 14:35 ` Fuad Tabba
2023-10-27 18:22 ` [PATCH v13 22/35] KVM: Allow arch code to track number of memslot address spaces per VM Sean Christopherson
2023-10-30 17:34 ` Paolo Bonzini
2023-11-02 14:52 ` Fuad Tabba
2023-10-27 18:22 ` [PATCH v13 23/35] KVM: x86: Add support for "protected VMs" that can utilize private memory Sean Christopherson
2023-10-30 17:36 ` Paolo Bonzini
2023-11-06 11:00 ` Fuad Tabba
2023-11-06 11:03 ` Paolo Bonzini
2023-10-27 18:22 ` [PATCH v13 24/35] KVM: selftests: Drop unused kvm_userspace_memory_region_find() helper Sean Christopherson
2023-10-27 18:22 ` [PATCH v13 25/35] KVM: selftests: Convert lib's mem regions to KVM_SET_USER_MEMORY_REGION2 Sean Christopherson
2024-04-25 14:12 ` Dan Carpenter
2024-04-25 14:45 ` Shuah Khan
2024-04-25 15:09 ` Sean Christopherson
2024-04-25 16:22 ` Shuah Khan
2024-04-26 7:33 ` Jarkko Sakkinen
2023-10-27 18:22 ` [PATCH v13 26/35] KVM: selftests: Add support for creating private memslots Sean Christopherson
2023-10-27 18:22 ` [PATCH v13 27/35] KVM: selftests: Add helpers to convert guest memory b/w private and shared Sean Christopherson
2023-11-06 11:26 ` Fuad Tabba
2023-10-27 18:22 ` [PATCH v13 28/35] KVM: selftests: Add helpers to do KVM_HC_MAP_GPA_RANGE hypercalls (x86) Sean Christopherson
2023-10-27 18:22 ` [PATCH v13 29/35] KVM: selftests: Introduce VM "shape" to allow tests to specify the VM type Sean Christopherson
2023-10-27 18:22 ` [PATCH v13 30/35] KVM: selftests: Add GUEST_SYNC[1-6] macros for synchronizing more data Sean Christopherson
2023-10-27 18:22 ` [PATCH v13 31/35] KVM: selftests: Add x86-only selftest for private memory conversions Sean Christopherson
2023-10-27 18:22 ` [PATCH v13 32/35] KVM: selftests: Add KVM_SET_USER_MEMORY_REGION2 helper Sean Christopherson
2023-10-27 18:22 ` [PATCH v13 33/35] KVM: selftests: Expand set_memory_region_test to validate guest_memfd() Sean Christopherson
2023-10-27 18:22 ` [PATCH v13 34/35] KVM: selftests: Add basic selftest for guest_memfd() Sean Christopherson
2023-10-27 18:22 ` [PATCH v13 35/35] KVM: selftests: Test KVM exit behavior for private memory/access Sean Christopherson
2023-10-30 17:39 ` [PATCH v13 00/35] KVM: guest_memfd() and per-page attributes Paolo Bonzini
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