Introduce kvm_gmem_hugetlb_get_folio(), then update kvm_gmem_allocate() and kvm_gmem_truncate() to use hugetlb functions.
Signed-off-by: Ackerley Tng ackerleytng@google.com --- virt/kvm/guest_mem.c | 215 +++++++++++++++++++++++++++++++++++++------ 1 file changed, 188 insertions(+), 27 deletions(-)
diff --git a/virt/kvm/guest_mem.c b/virt/kvm/guest_mem.c index b533143e2878..6271621f6b73 100644 --- a/virt/kvm/guest_mem.c +++ b/virt/kvm/guest_mem.c @@ -43,6 +43,95 @@ static loff_t kvm_gmem_get_size(struct file *file) return i_size_read(file_inode(file)); }
+static struct folio *kvm_gmem_hugetlb_alloc_and_cache_folio( + struct file *file, pgoff_t hindex) +{ + int err; + struct folio *folio; + struct kvm_gmem *gmem; + struct hstate *h; + struct resv_map *resv_map; + unsigned long offset; + struct vm_area_struct pseudo_vma; + + gmem = file->private_data; + h = gmem->hugetlb.h; + resv_map = gmem->hugetlb.resv_map; + offset = hindex << huge_page_shift(h); + + vma_init(&pseudo_vma, NULL); + vm_flags_init(&pseudo_vma, VM_HUGETLB | VM_MAYSHARE | VM_SHARED); + /* vma infrastructure is dependent on vm_file being set */ + pseudo_vma.vm_file = file; + + /* TODO setup NUMA policy. Meanwhile, fallback to get_task_policy(). */ + pseudo_vma.vm_policy = NULL; + folio = alloc_hugetlb_folio_from_subpool( + gmem->hugetlb.spool, h, resv_map, &pseudo_vma, offset, 0); + /* Remember to take and drop refcount from vm_policy */ + if (IS_ERR(folio)) + return folio; + + /* + * FIXME: Skip clearing pages when trusted firmware will do it when + * assigning memory to the guest. + */ + clear_huge_page(&folio->page, offset, pages_per_huge_page(h)); + __folio_mark_uptodate(folio); + err = hugetlb_filemap_add_folio(file->f_mapping, h, folio, hindex); + if (unlikely(err)) { + restore_reserve_on_error(resv_map, hindex, true, folio); + folio_put(folio); + folio = ERR_PTR(err); + } + + return folio; +} + +/** + * Gets a hugetlb folio, from @file, at @index (in terms of PAGE_SIZE) within + * the file. + * + * The returned folio will be in @file's page cache, and locked. + */ +static struct folio *kvm_gmem_hugetlb_get_folio(struct file *file, pgoff_t index) +{ + struct folio *folio; + u32 hash; + /* hindex is in terms of huge_page_size(h) and not PAGE_SIZE */ + pgoff_t hindex; + struct kvm_gmem *gmem; + struct hstate *h; + struct address_space *mapping; + + gmem = file->private_data; + h = gmem->hugetlb.h; + hindex = index >> huge_page_order(h); + + mapping = file->f_mapping; + hash = hugetlb_fault_mutex_hash(mapping, hindex); + mutex_lock(&hugetlb_fault_mutex_table[hash]); + + rcu_read_lock(); + folio = filemap_lock_folio(mapping, hindex); + rcu_read_unlock(); + if (folio) + goto folio_valid; + + folio = kvm_gmem_hugetlb_alloc_and_cache_folio(file, hindex); + /* + * TODO Perhaps the interface of kvm_gmem_get_folio should change to better + * report errors + */ + if (IS_ERR(folio)) + folio = NULL; + +folio_valid: + mutex_unlock(&hugetlb_fault_mutex_table[hash]); + + return folio; +} + static struct folio *kvm_gmem_get_huge_folio(struct file *file, pgoff_t index) { #ifdef CONFIG_TRANSPARENT_HUGEPAGE @@ -74,36 +163,56 @@ static struct folio *kvm_gmem_get_huge_folio(struct file *file, pgoff_t index) #endif }
+/** + * Gets a folio, from @file, at @index (in terms of PAGE_SIZE) within the file. + * + * The returned folio will be in @file's page cache and locked. + */ static struct folio *kvm_gmem_get_folio(struct file *file, pgoff_t index) { struct folio *folio; + struct kvm_gmem *gmem = file->private_data;
- folio = kvm_gmem_get_huge_folio(file, index); - if (!folio) { - folio = filemap_grab_folio(file->f_mapping, index); + if (gmem->flags & KVM_GUEST_MEMFD_HUGETLB) { + folio = kvm_gmem_hugetlb_get_folio(file, index); + + /* hugetlb gmem does not fall back to non-hugetlb pages */ if (!folio) return NULL; - }
- /* - * TODO: Confirm this won't zero in-use pages, and skip clearing pages - * when trusted firmware will do it when assigning memory to the guest. - */ - if (!folio_test_uptodate(folio)) { - unsigned long nr_pages = folio_nr_pages(folio); - unsigned long i; + /* + * Don't need to clear pages because + * kvm_gmem_hugetlb_alloc_and_cache_folio() already clears pages + * when allocating + */ + } else { + folio = kvm_gmem_get_huge_folio(file, index); + if (!folio) { + folio = filemap_grab_folio(file->f_mapping, index); + if (!folio) + return NULL; + }
- for (i = 0; i < nr_pages; i++) - clear_highpage(folio_page(folio, i)); - } + /* + * TODO: Confirm this won't zero in-use pages, and skip clearing pages + * when trusted firmware will do it when assigning memory to the guest. + */ + if (!folio_test_uptodate(folio)) { + unsigned long nr_pages = folio_nr_pages(folio); + unsigned long i;
- /* - * filemap_grab_folio() uses FGP_ACCESSED, which already called - * folio_mark_accessed(), so we clear it. - * TODO: Should we instead be clearing this when truncating? - * TODO: maybe don't use FGP_ACCESSED at all and call __filemap_get_folio directly. - */ - folio_clear_referenced(folio); + for (i = 0; i < nr_pages; i++) + clear_highpage(folio_page(folio, i)); + } + + /* + * filemap_grab_folio() uses FGP_ACCESSED, which already called + * folio_mark_accessed(), so we clear it. + * TODO: Should we instead be clearing this when truncating? + * TODO: maybe don't use FGP_ACCESSED at all and call __filemap_get_folio directly. + */ + folio_clear_referenced(folio); + }
/* * Indicate that this folio matches the backing store (in this case, has @@ -156,6 +265,44 @@ static void kvm_gmem_invalidate_end(struct kvm *kvm, struct kvm_gmem *gmem, KVM_MMU_UNLOCK(kvm); }
+static void kvm_gmem_hugetlb_truncate_range(struct inode *inode, + loff_t offset, loff_t len) +{ + loff_t hsize; + loff_t full_hpage_start; + loff_t full_hpage_end; + struct kvm_gmem *gmem; + struct hstate *h; + struct address_space *mapping; + + mapping = inode->i_mapping; + gmem = mapping->private_data; + h = gmem->hugetlb.h; + hsize = huge_page_size(h); + full_hpage_start = round_up(offset, hsize); + full_hpage_end = round_down(offset + len, hsize); + + /* If range starts before first full page, zero partial page. */ + if (offset < full_hpage_start) { + hugetlb_zero_partial_page( + h, mapping, offset, min(offset + len, full_hpage_start)); + } + + /* Remove full pages from the file. */ + if (full_hpage_end > full_hpage_start) { + remove_mapping_hugepages(mapping, h, gmem->hugetlb.spool, + gmem->hugetlb.resv_map, inode, + full_hpage_start, full_hpage_end); + } + + + /* If range extends beyond last full page, zero partial page. */ + if ((offset + len) > full_hpage_end && (offset + len) > full_hpage_start) { + hugetlb_zero_partial_page( + h, mapping, full_hpage_end, offset + len); + } +} + static long kvm_gmem_punch_hole(struct file *file, loff_t offset, loff_t len) { struct kvm_gmem *gmem = file->private_data; @@ -171,7 +318,10 @@ static long kvm_gmem_punch_hole(struct file *file, loff_t offset, loff_t len)
kvm_gmem_invalidate_begin(kvm, gmem, start, end);
- truncate_inode_pages_range(file->f_mapping, offset, offset + len - 1); + if (gmem->flags & KVM_GUEST_MEMFD_HUGETLB) + kvm_gmem_hugetlb_truncate_range(file_inode(file), offset, len); + else + truncate_inode_pages_range(file->f_mapping, offset, offset + len - 1);
kvm_gmem_invalidate_end(kvm, gmem, start, end);
@@ -183,6 +333,7 @@ static long kvm_gmem_punch_hole(struct file *file, loff_t offset, loff_t len) static long kvm_gmem_allocate(struct file *file, loff_t offset, loff_t len) { struct address_space *mapping = file->f_mapping; + struct kvm_gmem *gmem = file->private_data; pgoff_t start, index, end; int r;
@@ -192,9 +343,14 @@ static long kvm_gmem_allocate(struct file *file, loff_t offset, loff_t len)
filemap_invalidate_lock_shared(mapping);
- start = offset >> PAGE_SHIFT; - /* Align so that at least 1 page is allocated */ - end = ALIGN(offset + len, PAGE_SIZE) >> PAGE_SHIFT; + if (gmem->flags & KVM_GUEST_MEMFD_HUGETLB) { + start = offset >> huge_page_shift(gmem->hugetlb.h); + end = ALIGN(offset + len, huge_page_size(gmem->hugetlb.h)) >> PAGE_SHIFT; + } else { + start = offset >> PAGE_SHIFT; + /* Align so that at least 1 page is allocated */ + end = ALIGN(offset + len, PAGE_SIZE) >> PAGE_SHIFT; + }
r = 0; for (index = start; index < end; ) { @@ -211,7 +367,7 @@ static long kvm_gmem_allocate(struct file *file, loff_t offset, loff_t len) break; }
- index = folio_next_index(folio); + index += folio_nr_pages(folio);
folio_unlock(folio); folio_put(folio); @@ -625,7 +781,12 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot, return -ENOMEM; }
- page = folio_file_page(folio, index); + /* + * folio_file_page() always returns the head page for hugetlb + * folios. Reimplement to get the page within this folio, even for + * hugetlb pages. + */ + page = folio_page(folio, index & (folio_nr_pages(folio) - 1));
*pfn = page_to_pfn(page); *order = thp_order(compound_head(page));