linux-kernel - [PATCH 2/3] KVM: gmem: add a complete set of functions to query page preparedness

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20241108155056.332412-3-pbonzini@redhat.com>
Date: Fri,  8 Nov 2024 10:50:55 -0500
From: Paolo Bonzini <pbonzini@...hat.com>
To: linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org
Cc: michael.roth@....com,
	seanjc@...gle.com
Subject: [PATCH 2/3] KVM: gmem: add a complete set of functions to query page preparedness

In preparation for moving preparedness out of the folio flags, pass
the struct file* or struct inode* down to kvm_gmem_mark_prepared,
as well as the offset within the gmem file.  Introduce new functions
to unprepare page on punch-hole, and to query the state.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 virt/kvm/guest_memfd.c | 27 ++++++++++++++++++++-------
 1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
index 3ea5a7597fd4..416e02a00cae 100644
--- a/virt/kvm/guest_memfd.c
+++ b/virt/kvm/guest_memfd.c
@@ -107,18 +107,28 @@ static int __kvm_gmem_prepare_folio(struct kvm *kvm, struct kvm_memory_slot *slo
 	return 0;
 }
 
-static inline void kvm_gmem_mark_prepared(struct folio *folio)
+static void kvm_gmem_mark_prepared(struct file *file, pgoff_t index, struct folio *folio)
 {
 	folio_mark_uptodate(folio);
 }
 
+static void kvm_gmem_mark_range_unprepared(struct inode *inode, pgoff_t index, pgoff_t npages)
+{
+}
+
+static bool kvm_gmem_is_prepared(struct file *file, pgoff_t index, struct folio *folio)
+{
+	return folio_test_uptodate(folio);
+}
+
 /*
  * Process @folio, which contains @gfn, so that the guest can use it.
  * The folio must be locked and the gfn must be contained in @slot.
  * On successful return the guest sees a zero page so as to avoid
  * leaking host data and the up-to-date flag is set.
  */
-static int kvm_gmem_prepare_folio(struct kvm *kvm, struct kvm_memory_slot *slot,
+static int kvm_gmem_prepare_folio(struct kvm *kvm, struct file *file,
+				  struct kvm_memory_slot *slot,
 				  gfn_t gfn, struct folio *folio)
 {
 	unsigned long nr_pages, i;
@@ -147,7 +157,7 @@ static int kvm_gmem_prepare_folio(struct kvm *kvm, struct kvm_memory_slot *slot,
 	index = ALIGN_DOWN(index, 1 << folio_order(folio));
 	r = __kvm_gmem_prepare_folio(kvm, slot, index, folio);
 	if (!r)
-		kvm_gmem_mark_prepared(folio);
+		kvm_gmem_mark_prepared(file, index, folio);
 
 	return r;
 }
@@ -231,6 +241,7 @@ static long kvm_gmem_punch_hole(struct inode *inode, loff_t offset, loff_t len)
 		kvm_gmem_invalidate_begin(gmem, start, end);
 
 	truncate_inode_pages_range(inode->i_mapping, offset, offset + len - 1);
+	kvm_gmem_mark_range_unprepared(inode, start, end - start);
 
 	list_for_each_entry(gmem, gmem_list, entry)
 		kvm_gmem_invalidate_end(gmem, start, end);
@@ -682,7 +693,7 @@ __kvm_gmem_get_pfn(struct file *file, struct kvm_memory_slot *slot,
 	if (max_order)
 		*max_order = 0;
 
-	*is_prepared = folio_test_uptodate(folio);
+	*is_prepared = kvm_gmem_is_prepared(file, index, folio);
 	return folio;
 }
 
@@ -704,7 +715,7 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot,
 	}
 
 	if (!is_prepared)
-		r = kvm_gmem_prepare_folio(kvm, slot, gfn, folio);
+		r = kvm_gmem_prepare_folio(kvm, file, slot, gfn, folio);
 
 	folio_unlock(folio);
 	if (r < 0)
@@ -781,8 +792,10 @@ long kvm_gmem_populate(struct kvm *kvm, gfn_t start_gfn, void __user *src, long
 
 		p = src ? src + i * PAGE_SIZE : NULL;
 		ret = post_populate(kvm, gfn, pfn, p, max_order, opaque);
-		if (!ret)
-			kvm_gmem_mark_prepared(folio);
+		if (!ret) {
+			pgoff_t index = gfn - slot->base_gfn + slot->gmem.pgoff;
+			kvm_gmem_mark_prepared(file, index, folio);
+		}
 
 put_folio_and_exit:
 		folio_put(folio);
-- 
2.43.5