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Date: Fri, 5 Dec 2025 16:58:31 +0000
From: "Kalyazin, Nikita" <kalyazin@...zon.co.uk>
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Subject: [PATCH v8 04/13] KVM: guest_memfd: Add stub for
 kvm_arch_gmem_invalidate

From: Patrick Roy <patrick.roy@...ux.dev>

Add a no-op stub for kvm_arch_gmem_invalidate if
CONFIG_HAVE_KVM_ARCH_GMEM_INVALIDATE=n. This allows defining
kvm_gmem_free_folio without ifdef-ery, which allows more cleanly using
guest_memfd's free_folio callback for non-arch-invalidation related
code.

Acked-by: David Hildenbrand (Red Hat)" <david@...nel.org
Signed-off-by: Patrick Roy <patrick.roy@...ux.dev>
Signed-off-by: Nikita Kalyazin <kalyazin@...zon.com>
---
 include/linux/kvm_host.h | 2 ++
 virt/kvm/guest_memfd.c   | 4 ----
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index d93f75b05ae2..27796a09d29b 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -2589,6 +2589,8 @@ long kvm_gmem_populate(struct kvm *kvm, gfn_t gfn, void __user *src, long npages
 
 #ifdef CONFIG_HAVE_KVM_ARCH_GMEM_INVALIDATE
 void kvm_arch_gmem_invalidate(kvm_pfn_t start, kvm_pfn_t end);
+#else
+static inline void kvm_arch_gmem_invalidate(kvm_pfn_t start, kvm_pfn_t end) { }
 #endif
 
 #ifdef CONFIG_KVM_GENERIC_PRE_FAULT_MEMORY
diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
index fdaea3422c30..92e7f8c1f303 100644
--- a/virt/kvm/guest_memfd.c
+++ b/virt/kvm/guest_memfd.c
@@ -527,7 +527,6 @@ static int kvm_gmem_error_folio(struct address_space *mapping, struct folio *fol
 	return MF_DELAYED;
 }
 
-#ifdef CONFIG_HAVE_KVM_ARCH_GMEM_INVALIDATE
 static void kvm_gmem_free_folio(struct folio *folio)
 {
 	struct page *page = folio_page(folio, 0);
@@ -536,15 +535,12 @@ static void kvm_gmem_free_folio(struct folio *folio)
 
 	kvm_arch_gmem_invalidate(pfn, pfn + (1ul << order));
 }
-#endif
 
 static const struct address_space_operations kvm_gmem_aops = {
 	.dirty_folio = noop_dirty_folio,
 	.migrate_folio	= kvm_gmem_migrate_folio,
 	.error_remove_folio = kvm_gmem_error_folio,
-#ifdef CONFIG_HAVE_KVM_ARCH_GMEM_INVALIDATE
 	.free_folio = kvm_gmem_free_folio,
-#endif
 };
 
 static int kvm_gmem_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
-- 
2.50.1

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