On 08.06.21 10:39, Christian Borntraeger wrote:
On 21.05.21 19:38, David Matlack wrote:vm_get_max_gfn() casts vm->max_gfn from a uint64_t to an unsigned int, which causes the upper 32-bits of the max_gfn to get truncated. Nobody noticed until now likely because vm_get_max_gfn() is only used as a mechanism to create a memslot in an unused region of the guest physical address space (the top), and the top of the 32-bit physical address space was always good enough. This fix reveals a bug in memslot_modification_stress_test which was trying to create a dummy memslot past the end of guest physical memory. Fix that by moving the dummy memslot lower. Fixes: 52200d0d944e ("KVM: selftests: Remove duplicate guest mode handling") Reviewed-by: Venkatesh Srinivas <venkateshs@xxxxxxxxxxxx> Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>As a heads up: I have not yet looked into this, but this broke demand_paging_test and kvm_page_table_test on s390: not ok 4 selftests: kvm: demand_paging_test # exit=254 # selftests: kvm: dirty_log_test # ==== Test Assertion Failure ==== # lib/kvm_util.c:900: ret == 0 # pid=245410 tid=245410 errno=22 - Invalid argument # 1 0x0000000001005457: vm_userspace_mem_region_add at kvm_util.c:900 # 2 0x0000000001002cbf: run_test at dirty_log_test.c:757 # 3 (inlined by) run_test at dirty_log_test.c:702 # 4 0x000000000100c055: for_each_guest_mode at guest_modes.c:37 # 5 0x00000000010022b5: main at dirty_log_test.c:929 (discriminator 3) # 6 0x000003ff96fabdb3: ?? ??:0 # 7 0x000000000100241d: .annobin_lto.hot at crt1.o:? # KVM_SET_USER_MEMORY_REGION IOCTL failed, # rc: -1 errno: 22 # slot: 1 flags: 0x1 # guest_phys_addr: 0xfffffbfe00000 size: 0x40100000
Ah. We do have a limit of 128TB for guest physical memory. The patch now made this apparent as we no longer cut the upper bits off.
