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accel/kvm: Set guest_memfd_offset to non-zero value only when guest_memfd is valid

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Current QEMU unconditionally sets the guest_memfd_offset of KVMSlot in
kvm_set_phys_mem(), which leads to the trace of kvm_set_user_memory looks:

kvm_set_user_memory AddrSpace#0 Slot#4 flags=0x2 gpa=0xe0000 size=0x20000 ua=0x7f5840de0000 guest_memfd=-1 guest_memfd_offset=0x3e0000 ret=0

It's confusing that the guest_memfd_offset has a non-zero value while
the guest_memfd is invalid (-1).

Change to only set guest_memfd_offset when guest_memfd is valid and
leave it as 0 when no valid guest_memfd.

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20250728115707.1374614-4-xiaoyao.li@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Xiaoyao Li 2025-07-28 19:57:07 +08:00 • committed by Paolo Bonzini
parent 80030f66ad
commit 00c0911c68
1 changed files with 2 additions and 1 deletions
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3
accel/kvm/kvm-all.c
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@ -1595,7 +1595,8 @@ static void kvm_set_phys_mem(KVMMemoryListener *kml,
mem->ram = ram;
mem->flags = kvm_mem_flags(mr);
mem->guest_memfd = mr->ram_block->guest_memfd;
mem->guest_memfd_offset = (uint8_t*)ram - mr->ram_block->host;
mem->guest_memfd_offset = mem->guest_memfd >= 0 ?
(uint8_t*)ram - mr->ram_block->host : 0;
kvm_slot_init_dirty_bitmap(mem);
err = kvm_set_user_memory_region(kml, mem, true);