diff options
| author | Fuad Tabba <tabba@google.com> | 2025-07-29 15:54:52 -0700 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2025-08-27 04:37:03 -0400 |
| commit | 3d3a04fad25a6621828518a2abe536142d2c1a7d (patch) | |
| tree | a72390ea2a3a669a23d63e7eeb8d1f59851429cd /virt | |
| parent | 32e200bd6e4407c31aef0392be041274bfa3f20e (diff) | |
KVM: Allow and advertise support for host mmap() on guest_memfd files
Now that all the x86 and arm64 plumbing for mmap() on guest_memfd is in
place, allow userspace to set GUEST_MEMFD_FLAG_MMAP and advertise support
via a new capability, KVM_CAP_GUEST_MEMFD_MMAP.
The availability of this capability is determined per architecture, and
its enablement for a specific guest_memfd instance is controlled by the
GUEST_MEMFD_FLAG_MMAP flag at creation time.
Update the KVM API documentation to detail the KVM_CAP_GUEST_MEMFD_MMAP
capability, the associated GUEST_MEMFD_FLAG_MMAP, and provide essential
information regarding support for mmap in guest_memfd.
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Shivank Garg <shivankg@amd.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20250729225455.670324-22-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt')
| -rw-r--r-- | virt/kvm/guest_memfd.c | 7 | ||||
| -rw-r--r-- | virt/kvm/kvm_main.c | 2 |
2 files changed, 8 insertions, 1 deletions
diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index d5b445548af4..08a6bc7d25b6 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -314,7 +314,9 @@ static pgoff_t kvm_gmem_get_index(struct kvm_memory_slot *slot, gfn_t gfn) static bool kvm_gmem_supports_mmap(struct inode *inode) { - return false; + const u64 flags = (u64)inode->i_private; + + return flags & GUEST_MEMFD_FLAG_MMAP; } static vm_fault_t kvm_gmem_fault_user_mapping(struct vm_fault *vmf) @@ -522,6 +524,9 @@ int kvm_gmem_create(struct kvm *kvm, struct kvm_create_guest_memfd *args) u64 flags = args->flags; u64 valid_flags = 0; + if (kvm_arch_supports_gmem_mmap(kvm)) + valid_flags |= GUEST_MEMFD_FLAG_MMAP; + if (flags & ~valid_flags) return -EINVAL; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 4f57cb92e109..18f29ef93543 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -4918,6 +4918,8 @@ static int kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg) #ifdef CONFIG_KVM_GUEST_MEMFD case KVM_CAP_GUEST_MEMFD: return 1; + case KVM_CAP_GUEST_MEMFD_MMAP: + return !kvm || kvm_arch_supports_gmem_mmap(kvm); #endif default: break; |