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KVM: guest_memfd: do not go through struct page 

We have a perfectly usable folio, use it to retrieve the pfn and order.
All that's needed is a version of folio_file_page that returns a pfn.

Reviewed-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
pull/925/head
Paolo Bonzini 2024-07-11 18:27:46 -04:00
parent d04c77d231
commit 7fbdda31b0
1 changed files with 17 additions and 10 deletions
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27
virt/kvm/guest_memfd.c
View File

@ -13,6 +13,18 @@ struct kvm_gmem {
struct list_head entry; struct list_head entry;
}; };
/**
* folio_file_pfn - like folio_file_page, but return a pfn.
* @folio: The folio which contains this index.
* @index: The index we want to look up.
*
* Return: The pfn for this index.
*/
static inline kvm_pfn_t folio_file_pfn(struct folio *folio, pgoff_t index)
{
return folio_pfn(folio) + (index & (folio_nr_pages(folio) - 1));
}
static int kvm_gmem_prepare_folio(struct inode *inode, pgoff_t index, struct folio *folio) static int kvm_gmem_prepare_folio(struct inode *inode, pgoff_t index, struct folio *folio)
{ {
#ifdef CONFIG_HAVE_KVM_GMEM_PREPARE #ifdef CONFIG_HAVE_KVM_GMEM_PREPARE
@ -22,7 +34,6 @@ static int kvm_gmem_prepare_folio(struct inode *inode, pgoff_t index, struct fol
list_for_each_entry(gmem, gmem_list, entry) { list_for_each_entry(gmem, gmem_list, entry) {
struct kvm_memory_slot *slot; struct kvm_memory_slot *slot;
struct kvm *kvm = gmem->kvm; struct kvm *kvm = gmem->kvm;
struct page *page;
kvm_pfn_t pfn; kvm_pfn_t pfn;
gfn_t gfn; gfn_t gfn;
int rc; int rc;
@ -34,13 +45,12 @@ static int kvm_gmem_prepare_folio(struct inode *inode, pgoff_t index, struct fol
if (!slot) if (!slot)
continue; continue;
page = folio_file_page(folio, index); pfn = folio_file_pfn(folio, index);
pfn = page_to_pfn(page);
gfn = slot->base_gfn + index - slot->gmem.pgoff; gfn = slot->base_gfn + index - slot->gmem.pgoff;
rc = kvm_arch_gmem_prepare(kvm, gfn, pfn, compound_order(compound_head(page))); rc = kvm_arch_gmem_prepare(kvm, gfn, pfn, folio_order(folio));
if (rc) { if (rc) {
pr_warn_ratelimited("gmem: Failed to prepare folio for index %lx GFN %llx PFN %llx error %d.\n", pr_warn_ratelimited("gmem: Failed to prepare folio for GFN %llx PFN %llx error %d.\n",
index, gfn, pfn, rc); gfn, pfn, rc);
return rc; return rc;
} }
} }
@ -548,7 +558,6 @@ __kvm_gmem_get_pfn(struct file *file, struct kvm_memory_slot *slot,
pgoff_t index = gfn - slot->base_gfn + slot->gmem.pgoff; pgoff_t index = gfn - slot->base_gfn + slot->gmem.pgoff;
struct kvm_gmem *gmem = file->private_data; struct kvm_gmem *gmem = file->private_data;
struct folio *folio; struct folio *folio;
struct page *page;
if (file != slot->gmem.file) { if (file != slot->gmem.file) {
WARN_ON_ONCE(slot->gmem.file); WARN_ON_ONCE(slot->gmem.file);
@ -571,9 +580,7 @@ __kvm_gmem_get_pfn(struct file *file, struct kvm_memory_slot *slot,
return ERR_PTR(-EHWPOISON); return ERR_PTR(-EHWPOISON);
} }
page = folio_file_page(folio, index); *pfn = folio_file_pfn(folio, index);
*pfn = page_to_pfn(page);
if (max_order) if (max_order)
*max_order = 0; *max_order = 0;