From: Ackerley Tng <[email protected]> Extract a helper out of kvm_gmem_range_is_private() that checks that a range has given attributes.
Optimize setting memory attributes by returning early if all pages in the requested range already has the requested attributes. Reviewed-by: Fuad Tabba <[email protected]> Tested-by: Shivank Garg <[email protected]> Signed-off-by: Ackerley Tng <[email protected]> --- virt/kvm/guest_memfd.c | 35 ++++++++++++++++++++++++----------- 1 file changed, 24 insertions(+), 11 deletions(-) diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index 612fcde4ae8ea..928fc7f4a01e4 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -94,6 +94,24 @@ static bool kvm_gmem_is_shared_mem(struct inode *inode, pgoff_t index) return !kvm_gmem_is_private_mem(inode, index); } +static bool kvm_gmem_range_has_attributes(struct inode *inode, + pgoff_t index, size_t nr_pages, + u64 attributes) +{ + struct maple_tree *mt = &GMEM_I(inode)->attributes; + pgoff_t end = index + nr_pages - 1; + void *entry; + + lockdep_assert(mt_lock_is_held(mt)); + + mt_for_each(mt, entry, index, end) { + if (kvm_gmem_interpret_entry(inode, entry) != attributes) + return false; + } + + return true; +} + /* * Returns a locked folio on success. The caller is responsible for * setting the up-to-date flag before the memory is mapped into the guest. @@ -611,12 +629,15 @@ static int __kvm_gmem_set_attributes(struct inode *inode, pgoff_t start, pgoff_t end = start + nr_pages; struct maple_tree *mt; struct ma_state mas; - int r; + int r = 0; mt = &gi->attributes; filemap_invalidate_lock(mapping); + if (kvm_gmem_range_has_attributes(inode, start, nr_pages, attrs)) + goto out; + mas_init(&mas, mt, start); r = kvm_gmem_mas_preallocate(&mas, attrs, start, nr_pages); if (r) { @@ -1107,22 +1128,14 @@ static bool kvm_range_is_private(struct file *file, pgoff_t index, size_t nr_pages, struct kvm *kvm, gfn_t gfn) { struct inode *inode = file_inode(file); - pgoff_t last = index + nr_pages - 1; - struct maple_tree *mt; - void *entry; if (!gmem_in_place_conversion) return kvm_range_has_vm_memory_attributes(kvm, gfn, gfn + nr_pages, KVM_MEMORY_ATTRIBUTE_PRIVATE, KVM_MEMORY_ATTRIBUTE_PRIVATE); - mt = &GMEM_I(inode)->attributes; - mt_for_each(mt, entry, index, last) { - if (kvm_gmem_interpret_entry(inode, entry) != - KVM_MEMORY_ATTRIBUTE_PRIVATE) - return false; - } - return true; + return kvm_gmem_range_has_attributes(inode, index, nr_pages, + KVM_MEMORY_ATTRIBUTE_PRIVATE); } static long __kvm_gmem_populate(struct kvm *kvm, struct kvm_memory_slot *slot, -- 2.55.0.508.g3f0d502094-goog
