[RFC PATCH 09/19] i386/kvm: Create gmem fd for KVM_X86_SW_PROTECTED_VM

[Xiaoyao Li <xiaoyao.li@xxxxxxxxx>]

Register a memory listener for KVM_X86_SW_PROVTED_VM. It creates gmem
for the backend who sets the private property.

Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
---
 include/exec/memory.h |  1 +
 target/i386/kvm/kvm.c | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/include/exec/memory.h b/include/exec/memory.h
index e119d3ce1a1d..ddf0e14970b0 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -814,6 +814,7 @@ struct IOMMUMemoryRegion {
 #define MEMORY_LISTENER_PRIORITY_MIN            0
 #define MEMORY_LISTENER_PRIORITY_ACCEL          10
 #define MEMORY_LISTENER_PRIORITY_DEV_BACKEND    10
+#define MEMORY_LISTENER_PRIORITY_ACCEL_HIGH     20
 
 /**
  * struct MemoryListener: callbacks structure for updates to the physical memory map
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 7971f0fd74b1..df3a5f89396e 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -37,6 +37,7 @@
 #include "hyperv-proto.h"
 
 #include "exec/gdbstub.h"
+#include "exec/ramblock.h"
 #include "qemu/host-utils.h"
 #include "qemu/main-loop.h"
 #include "qemu/ratelimit.h"
@@ -2591,8 +2592,41 @@ static void register_smram_listener(Notifier *n, void *unused)
                                  &smram_address_space, 1, "kvm-smram");
 }
 
+static void kvm_x86_sw_protected_vm_region_add(MemoryListener *listenr,
+                                       MemoryRegionSection *section)
+{
+    MemoryRegion *mr = section->mr;
+    Object *owner = memory_region_owner(mr);
+    int fd;
+
+    if (owner && object_dynamic_cast(owner, TYPE_MEMORY_BACKEND) &&
+        object_property_get_bool(owner, "private", NULL) &&
+        mr->ram_block && mr->ram_block->gmem_fd < 0) {
+        struct kvm_create_guest_memfd gmem = {
+            .size = memory_region_size(mr),
+            /* TODO: to decide whether KVM_GUEST_MEMFD_ALLOW_HUGEPAGE is supported */
+            .flags = KVM_GUEST_MEMFD_ALLOW_HUGEPAGE,
+        };
+
+        fd = kvm_vm_ioctl(kvm_state, KVM_CREATE_GUEST_MEMFD, &gmem);
+        if (fd < 0) {
+            error_report("%s: error creating gmem: %s\n", __func__, strerror(-fd));
+            exit(1);
+        }
+        memory_region_set_gmem_fd(mr, fd);
+    }
+}
+
+static MemoryListener kvm_x86_sw_protected_vm_memory_listener = {
+    .name = "kvm_x86_sw_protected_vm_memory_listener",
+    .region_add = kvm_x86_sw_protected_vm_region_add,
+    /* Higher than KVM memory listener = 10. */
+    .priority = MEMORY_LISTENER_PRIORITY_ACCEL_HIGH,
+};
+
 int kvm_arch_init(MachineState *ms, KVMState *s)
 {
+    X86MachineState *x86ms = X86_MACHINE(ms);
     uint64_t identity_base = 0xfffbc000;
     uint64_t shadow_mem;
     int ret;
@@ -2617,6 +2651,10 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
         return ret;
     }
 
+    if (x86ms->vm_type == KVM_X86_SW_PROTECTED_VM) {
+        memory_listener_register(&kvm_x86_sw_protected_vm_memory_listener, &address_space_memory);
+    }
+
     if (!kvm_check_extension(s, KVM_CAP_IRQ_ROUTING)) {
         error_report("kvm: KVM_CAP_IRQ_ROUTING not supported by KVM");
         return -ENOTSUP;
-- 
2.34.1