commit 37662d85b0b7dded0ebdf6747bef6c3bb7ed6a0c
author Xiaoyao Li <xiaoyao.li@intel.com> Wed Mar 20 03:39:03 2024 -0500
committer Paolo Bonzini <pbonzini@redhat.com> Tue Apr 23 17:35:25 2024 +0200
tree b5d8be3492b7aa7e3df4d1ec71a44180255077fb
parent bd3bcf6962b664ca3bf9c60fdcc4534e8e3d0641

HostMem: Add mechanism to opt in kvm guest memfd via MachineState

Add a new member "guest_memfd" to memory backends. When it's set
to true, it enables RAM_GUEST_MEMFD in ram_flags, thus private kvm
guest_memfd will be allocated during RAMBlock allocation.

Memory backend's @guest_memfd is wired with @require_guest_memfd
field of MachineState. It avoid looking up the machine in phymem.c.

MachineState::require_guest_memfd is supposed to be set by any VMs
that requires KVM guest memfd as private memory, e.g., TDX VM.

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Message-ID: <20240320083945.991426-8-michael.roth@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

backends/hostmem-file.c

diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c
index ac3e433..3c69db7 100644
--- a/backends/hostmem-file.c
+++ b/backends/hostmem-file.c
@@ -85,6 +85,7 @@
     ram_flags |= fb->readonly ? RAM_READONLY_FD : 0;
     ram_flags |= fb->rom == ON_OFF_AUTO_ON ? RAM_READONLY : 0;
     ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
+    ram_flags |= backend->guest_memfd ? RAM_GUEST_MEMFD : 0;
     ram_flags |= fb->is_pmem ? RAM_PMEM : 0;
     ram_flags |= RAM_NAMED_FILE;
     return memory_region_init_ram_from_file(&backend->mr, OBJECT(backend), name,

backends/hostmem-memfd.c

diff --git a/backends/hostmem-memfd.c b/backends/hostmem-memfd.c
index 3923ea9..745ead0 100644
--- a/backends/hostmem-memfd.c
+++ b/backends/hostmem-memfd.c
@@ -55,6 +55,7 @@
     name = host_memory_backend_get_name(backend);
     ram_flags = backend->share ? RAM_SHARED : 0;
     ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
+    ram_flags |= backend->guest_memfd ? RAM_GUEST_MEMFD : 0;
     return memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend), name,
                                           backend->size, ram_flags, fd, 0, errp);
 }

backends/hostmem-ram.c

diff --git a/backends/hostmem-ram.c b/backends/hostmem-ram.c
index d121249..f7d81af 100644
--- a/backends/hostmem-ram.c
+++ b/backends/hostmem-ram.c
@@ -30,6 +30,7 @@
     name = host_memory_backend_get_name(backend);
     ram_flags = backend->share ? RAM_SHARED : 0;
     ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
+    ram_flags |= backend->guest_memfd ? RAM_GUEST_MEMFD : 0;
     return memory_region_init_ram_flags_nomigrate(&backend->mr, OBJECT(backend),
                                                   name, backend->size,
                                                   ram_flags, errp);

backends/hostmem.c

diff --git a/backends/hostmem.c b/backends/hostmem.c
index 81a72ce..eb9682b 100644
--- a/backends/hostmem.c
+++ b/backends/hostmem.c
@@ -277,6 +277,7 @@
     /* TODO: convert access to globals to compat properties */
     backend->merge = machine_mem_merge(machine);
     backend->dump = machine_dump_guest_core(machine);
+    backend->guest_memfd = machine_require_guest_memfd(machine);
     backend->reserve = true;
     backend->prealloc_threads = machine->smp.cpus;
 }