On Wed, Mar 20, 2024 at 03:39:03AM -0500, Michael Roth wrote: > From: Xiaoyao Li <xiaoyao.li@xxxxxxxxx> > > 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@xxxxxxxxx> > Reviewed-by: David Hildenbrand <david@xxxxxxxxxx> > --- > Changes in v4: > - rename "require_guest_memfd" to "guest_memfd" in struct > HostMemoryBackend; (David Hildenbrand) > Signed-off-by: Michael Roth <michael.roth@xxxxxxx> > --- > 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 ac3e433cbd..3c69db7946 100644 > --- a/backends/hostmem-file.c > +++ b/backends/hostmem-file.c > @@ -85,6 +85,7 @@ 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->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, > diff --git a/backends/hostmem-memfd.c b/backends/hostmem-memfd.c > index 3923ea9364..745ead0034 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->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); > } > diff --git a/backends/hostmem-ram.c b/backends/hostmem-ram.c > index d121249f0f..f7d81af783 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->guest_memfd ? RAM_GUEST_MEMFD : 0; > return memory_region_init_ram_flags_nomigrate(&backend->mr, OBJECT(backend), > name, backend->size, > ram_flags, errp); These change look a bit confusing to me, as I don't see how gmemfd can be used with either file or ram typed memory backends.. When specified gmemfd=on with those, IIUC it'll allocate both the memory (ramblock->host) and gmemfd, but without using ->host. Meanwhile AFAIU the ramblock->host will start to conflict with gmemfd in the future when it might be able to be mapp-able (having valid ->host). I have a local fix for this (and actually more than below.. but starting from it), I'm not sure whether I overlooked something, but from reading the cover letter it's only using memfd backend which makes perfect sense to me so far. I also don't know the planning of coco patches merging so I don't think even if valid this is urgent - I don't want to mess up on merging plans.. but still want to collect some comments on whether it's valid: ===8<===
