[RFC v2 PATCH 04/13] KVM: Add fd-based memslot data structure and utils

Chao Peng
2021-11-19T13:49:25Z

For fd-based memslot store the file references for shared fd and the
private fd (if any) in the memslot structure. Since there is no 'hva'
concept we cannot call hva_to_pfn() to get a pfn, instead kvm_memfd_ops
is added to get_pfn/put_pfn from the memory backing stores that provide
these fds.

Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
---
include/linux/kvm_host.h | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 99e9f9969703..1d4ac0c9b63b 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -424,6 +424,12 @@ static inline int kvm_vcpu_exiting_guest_mode(struct kvm_vcpu *vcpu)
*/
#define KVM_MEM_MAX_NR_PAGES ((1UL << 31) - 1)

+struct kvm_memfd_ops {
+ kvm_pfn_t (*get_pfn)(struct kvm_memory_slot *slot, struct file *file,
+ gfn_t gfn, bool alloc, int *order);
+ void (*put_pfn)(kvm_pfn_t pfn);
+};
+
struct kvm_memory_slot {
gfn_t base_gfn;
unsigned long npages;
@@ -433,6 +439,9 @@ struct kvm_memory_slot {
u32 flags;
short id;
u16 as_id;
+ struct file *file;
+ struct file *priv_file;
+ struct kvm_memfd_ops *memfd_ops;
};

static inline bool kvm_slot_dirty_track_enabled(struct kvm_memory_slot *slot)
@@ -1310,6 +1319,20 @@ static inline int memslot_id(struct kvm *kvm, gfn_t gfn)
return gfn_to_memslot(kvm, gfn)->id;
}

+static inline bool memslot_is_memfd(const struct kvm_memory_slot *slot)
+{
+ if (slot && slot->memfd_ops)
+ return true;
+ return false;
+}
+
+static inline bool memslot_has_private(const struct kvm_memory_slot *slot)
+{
+ if (slot && slot->priv_file)
+ return true;
+ return false;
+}
+
static inline gfn_t
hva_to_gfn_memslot(unsigned long hva, struct kvm_memory_slot *slot)
{
--
2.17.1