[PATCH v3 04/70] HostMem: Add mechanism to opt in kvm guest memfd via MachineState

Xiaoyao Li
2023-11-15T07:16:03Z

Add a new member "require_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 @require_guest_memfd is wired with @require_guest_memfd
field of MachineState. 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>
---
backends/hostmem-file.c | 1 +
backends/hostmem-memfd.c | 1 +
backends/hostmem-ram.c | 1 +
backends/hostmem.c | 1 +
hw/core/machine.c | 5 +++++
include/hw/boards.h | 2 ++
include/sysemu/hostmem.h | 1 +
7 files changed, 12 insertions(+)

diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c
index 361d4a8103ef..d5ea2879f321 100644
--- a/backends/hostmem-file.c
+++ b/backends/hostmem-file.c
@@ -84,6 +84,7 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
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->require_guest_memfd ? RAM_GUEST_MEMFD : 0;
ram_flags |= fb->is_pmem ? RAM_PMEM : 0;
ram_flags |= RAM_NAMED_FILE;
memory_region_init_ram_from_file(&backend->mr, OBJECT(backend), name,
diff --git a/backends/hostmem-memfd.c b/backends/hostmem-memfd.c
index 3fc85c3db81b..011e2311f088 100644
--- a/backends/hostmem-memfd.c
+++ b/backends/hostmem-memfd.c
@@ -55,6 +55,7 @@ memfd_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
name = host_memory_backend_get_name(backend);
ram_flags = backend->share ? RAM_SHARED : 0;
ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
+ ram_flags |= backend->require_guest_memfd ? RAM_GUEST_MEMFD : 0;
memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend), name,
backend->size, ram_flags, fd, 0, errp);
g_free(name);
diff --git a/backends/hostmem-ram.c b/backends/hostmem-ram.c
index b8e55cdbd0f8..7d2e1327f8c8 100644
--- a/backends/hostmem-ram.c
+++ b/backends/hostmem-ram.c
@@ -30,6 +30,7 @@ ram_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
name = host_memory_backend_get_name(backend);
ram_flags = backend->share ? RAM_SHARED : 0;
ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
+ ram_flags |= backend->require_guest_memfd ? RAM_GUEST_MEMFD : 0;
memory_region_init_ram_flags_nomigrate(&backend->mr, OBJECT(backend), name,
backend->size, ram_flags, errp);
g_free(name);
diff --git a/backends/hostmem.c b/backends/hostmem.c
index 747e7838c031..2deb2b78bcb8 100644
--- a/backends/hostmem.c
+++ b/backends/hostmem.c
@@ -279,6 +279,7 @@ static void host_memory_backend_init(Object *obj)
/* TODO: convert access to globals to compat properties */
backend->merge = machine_mem_merge(machine);
backend->dump = machine_dump_guest_core(machine);
+ backend->require_guest_memfd = machine_require_guest_memfd(machine);
backend->reserve = true;
backend->prealloc_threads = machine->smp.cpus;
}
diff --git a/hw/core/machine.c b/hw/core/machine.c
index 0c1739814124..b1b0a46ea52f 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -1189,6 +1189,11 @@ bool machine_mem_merge(MachineState *machine)
return machine->mem_merge;
}

+bool machine_require_guest_memfd(MachineState *machine)
+{
+ return machine->require_guest_memfd;
+}
+
static char *cpu_slot_to_string(const CPUArchId *cpu)
{
GString *s = g_string_new(NULL);
diff --git a/include/hw/boards.h b/include/hw/boards.h
index a7359992980a..227aded07209 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -30,6 +30,7 @@ bool machine_usb(MachineState *machine);
int machine_phandle_start(MachineState *machine);
bool machine_dump_guest_core(MachineState *machine);
bool machine_mem_merge(MachineState *machine);
+bool machine_require_guest_memfd(MachineState *machine);
HotpluggableCPUList *machine_query_hotpluggable_cpus(MachineState *machine);
void machine_set_cpu_numa_node(MachineState *machine,
const CpuInstanceProperties *props,
@@ -364,6 +365,7 @@ struct MachineState {
char *dt_compatible;
bool dump_guest_core;
bool mem_merge;
+ bool require_guest_memfd;
bool usb;
bool usb_disabled;
char *firmware;
diff --git a/include/sysemu/hostmem.h b/include/sysemu/hostmem.h
index 39326f1d4f9c..92f7fd469639 100644
--- a/include/sysemu/hostmem.h
+++ b/include/sysemu/hostmem.h
@@ -66,6 +66,7 @@ struct HostMemoryBackend {
uint64_t size;
bool merge, dump, use_canonical_path;
bool prealloc, is_mapped, share, reserve;
+ bool require_guest_memfd;
uint32_t prealloc_threads;
ThreadContext *prealloc_context;
DECLARE_BITMAP(host_nodes, MAX_NODES + 1);
--
2.34.1