From b1c3368c4b8cc033d5d8769d7fa669e4bbb8697c Mon Sep 17 00:00:00 2001 From: Xiaoyao Li Date: Mon, 31 Jul 2023 04:20:52 -0400 Subject: [PATCH] kvm/memory: Make memory type private by default if it has guest memfd backend KVM side leaves the memory to shared by default, while may incur the overhead of paging conversion on the first visit of each page. Because the expectation is that page is likely to private for the VMs that require private memory (has guest memfd). Explicitly set the memory to private when memory region has valid guest memfd backend. Signed-off-by: Xiaoyao Li --- accel/kvm/kvm-all.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c index fe2eb3f069..0c0719a030 100644 --- a/accel/kvm/kvm-all.c +++ b/accel/kvm/kvm-all.c @@ -1451,6 +1451,16 @@ static void kvm_set_phys_mem(KVMMemoryListener *kml, strerror(-err)); abort(); } + + if (memory_region_has_guest_memfd(mr)) { + err = kvm_set_memory_attributes_private(start_addr, slot_size); + if (err) { + error_report("%s: failed to set memory attribute private: %s\n", + __func__, strerror(-err)); + exit(1); + } + } + start_addr += slot_size; ram_start_offset += slot_size; ram += slot_size;