On 7/23/2025 8:06 PM, Philippe Mathieu-Daudé wrote:
On 23/7/25 09:09, Xiaoyao Li wrote:
Current QEMU unconditionally sets the mmem.guest_memfd_offset in
kvm_set_user_memory_region(), which leads to the trace of
kvm_set_user_memory
look as:
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.
Signed-off-by: Xiaoyao Li <xiaoyao...@intel.com>
---
accel/kvm/kvm-all.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 4f4c30fc84b2..2b6fbf58a127 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -367,7 +367,9 @@ static int
kvm_set_user_memory_region(KVMMemoryListener *kml, KVMSlot *slot, boo
mem.userspace_addr = (unsigned long)slot->ram;
mem.flags = slot->flags;
mem.guest_memfd = slot->guest_memfd;
- mem.guest_memfd_offset = slot->guest_memfd_offset;
+ if (slot->guest_memfd >= 0) {
+ mem.guest_memfd_offset = slot->guest_memfd_offset;
+ }
IMHO the issue is in when the KVMSlot is filled in kvm_set_phys_mem():
Agreed, fix it in the origin。
-- >8 --
diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 890d5ea9f86..631f14b996a 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -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 = mr->ram_block->guest_memfd
+ ? (uint8_t*)ram - mr->ram_block->host : 0;
it should be
mr->ram_block->guest_memfd >= 0 ? (uint8_t*)ram - mr->ram_block->host :
0;
I will use the fixed version in v2.
Thanks!
kvm_slot_init_dirty_bitmap(mem);
err = kvm_set_user_memory_region(kml, mem, true);
---
