[RFC PATCH v5 01/16] KVM: guest_memfd: Add a handle for provider PFNs

["Aneesh Kumar K.V (Arm)" <aneesh.kumar@kernel.org>]

Add an MMIO PFN flag, separate from KVM memory attributes.

Add struct guest_memfd_handle to hold a PFN, its attributes, the order
of the contiguous range and an optional folio reference. Later patches
use this handle for both folio and PFN providers.

Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
---
 include/linux/guest_memfd.h | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/include/linux/guest_memfd.h b/include/linux/guest_memfd.h
index 3e2c0714ca33..659d7d4baa58 100644
--- a/include/linux/guest_memfd.h
+++ b/include/linux/guest_memfd.h
@@ -2,13 +2,30 @@
 #ifndef _LINUX_GUEST_MEMFD_H
 #define _LINUX_GUEST_MEMFD_H
 
+#include <linux/bits.h>
 #include <linux/types.h>
 
+#define GUEST_MEMFD_PFN_MMIO	BIT_ULL(0)
+
 struct file;
 struct folio;
 struct inode;
 struct mempolicy;
 
+/**
+ * struct guest_memfd_handle - PFN information and an optional folio reference
+ * @pfn: Physical frame number
+ * @pfn_attrs: GUEST_MEMFD_PFN_* memory type and permissions
+ * @max_order: Largest order of a contiguous range with the same PFN attributes
+ * @folio: Optional locked folio reference, managed by the core
+ */
+struct guest_memfd_handle {
+	unsigned long pfn;
+	u64 pfn_attrs;
+	int max_order;
+	struct folio *folio;
+};
+
 /**
  * struct guest_memfd_provider_operations - Operations for external memory providers
  * @attach: Attach to a resource file, perform filesystem-specific validation,
-- 
2.43.0