From: Sean Christopherson seanjc@google.com
[ Upstream commit 4af18dc6a9204464db76d9771d1f40e2b46bf6ae ]
Refactor guest_memfd usage of __kvm_gmem_get_pfn() to pass the index into the guest_memfd file instead of the gfn, i.e. resolve the index based on the slot+gfn in the caller instead of in __kvm_gmem_get_pfn(). This will allow kvm_gmem_get_pfn() to retrieve and return the specific "struct page", which requires the index into the folio, without a redoing the index calculation multiple times (which isn't costly, just hard to follow).
Opportunistically add a kvm_gmem_get_index() helper to make the copy+pasted code easier to understand.
Signed-off-by: Sean Christopherson seanjc@google.com Tested-by: Dmitry Osipenko dmitry.osipenko@collabora.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Message-ID: 20241010182427.1434605-46-seanjc@google.com Stable-dep-of: ae431059e75d ("KVM: guest_memfd: Remove bindings on memslot deletion when gmem is dying") Signed-off-by: Sasha Levin sashal@kernel.org --- virt/kvm/guest_memfd.c | 20 +++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-)
diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index bb062d3d24572..73e5db8ef1611 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -304,6 +304,11 @@ static inline struct file *kvm_gmem_get_file(struct kvm_memory_slot *slot) return get_file_active(&slot->gmem.file); }
+static pgoff_t kvm_gmem_get_index(struct kvm_memory_slot *slot, gfn_t gfn) +{ + return gfn - slot->base_gfn + slot->gmem.pgoff; +} + static struct file_operations kvm_gmem_fops = { .open = generic_file_open, .release = kvm_gmem_release, @@ -553,12 +558,11 @@ void kvm_gmem_unbind(struct kvm_memory_slot *slot) }
/* Returns a locked folio on success. */ -static struct folio * -__kvm_gmem_get_pfn(struct file *file, struct kvm_memory_slot *slot, - gfn_t gfn, kvm_pfn_t *pfn, bool *is_prepared, - int *max_order) +static struct folio *__kvm_gmem_get_pfn(struct file *file, + struct kvm_memory_slot *slot, + pgoff_t index, kvm_pfn_t *pfn, + bool *is_prepared, int *max_order) { - pgoff_t index = gfn - slot->base_gfn + slot->gmem.pgoff; struct kvm_gmem *gmem = file->private_data; struct folio *folio;
@@ -594,6 +598,7 @@ __kvm_gmem_get_pfn(struct file *file, struct kvm_memory_slot *slot, int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn, kvm_pfn_t *pfn, int *max_order) { + pgoff_t index = kvm_gmem_get_index(slot, gfn); struct file *file = kvm_gmem_get_file(slot); struct folio *folio; bool is_prepared = false; @@ -602,7 +607,7 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot, if (!file) return -EFAULT;
- folio = __kvm_gmem_get_pfn(file, slot, gfn, pfn, &is_prepared, max_order); + folio = __kvm_gmem_get_pfn(file, slot, index, pfn, &is_prepared, max_order); if (IS_ERR(folio)) { r = PTR_ERR(folio); goto out; @@ -650,6 +655,7 @@ long kvm_gmem_populate(struct kvm *kvm, gfn_t start_gfn, void __user *src, long for (i = 0; i < npages; i += (1 << max_order)) { struct folio *folio; gfn_t gfn = start_gfn + i; + pgoff_t index = kvm_gmem_get_index(slot, gfn); bool is_prepared = false; kvm_pfn_t pfn;
@@ -658,7 +664,7 @@ long kvm_gmem_populate(struct kvm *kvm, gfn_t start_gfn, void __user *src, long break; }
- folio = __kvm_gmem_get_pfn(file, slot, gfn, &pfn, &is_prepared, &max_order); + folio = __kvm_gmem_get_pfn(file, slot, index, &pfn, &is_prepared, &max_order); if (IS_ERR(folio)) { ret = PTR_ERR(folio); break;