diff options
| author | Fuad Tabba <tabba@google.com> | 2025-07-29 15:54:42 -0700 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2025-08-27 04:35:00 -0400 |
| commit | 576d035e2aef52f8d8d3ce29af556d4c6bd2e0fe (patch) | |
| tree | ba7e3deec682136b266a9d5e8665d7bf5b45dedb /virt | |
| parent | a12578e1477cbfb547256ed8dee6d5142a59cdcd (diff) | |
KVM: guest_memfd: Track guest_memfd mmap support in memslot
Add a new internal flag, KVM_MEMSLOT_GMEM_ONLY, to the top half of
memslot->flags (which makes it strictly for KVM's internal use). This
flag tracks when a guest_memfd-backed memory slot supports host
userspace mmap operations, which implies that all memory, not just
private memory for CoCo VMs, is consumed through guest_memfd: "gmem
only".
This optimization avoids repeatedly checking the underlying guest_memfd
file for mmap support, which would otherwise require taking and
releasing a reference on the file for each check. By caching this
information directly in the memslot, we reduce overhead and simplify the
logic involved in handling guest_memfd-backed pages for host mappings.
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Shivank Garg <shivankg@amd.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Acked-by: David Hildenbrand <david@redhat.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20250729225455.670324-12-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt')
| -rw-r--r-- | virt/kvm/guest_memfd.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index 67e7cd7210ef..d5b445548af4 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -578,6 +578,8 @@ int kvm_gmem_bind(struct kvm *kvm, struct kvm_memory_slot *slot, */ WRITE_ONCE(slot->gmem.file, file); slot->gmem.pgoff = start; + if (kvm_gmem_supports_mmap(inode)) + slot->flags |= KVM_MEMSLOT_GMEM_ONLY; xa_store_range(&gmem->bindings, start, end - 1, slot, GFP_KERNEL); filemap_invalidate_unlock(inode->i_mapping); |