lkml.org 
[lkml]   [2021]   [May]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: [PATCH] selftests: kvm: fix overlapping addresses in memslot_perf_test
    Date
    On 28/05/21 21:51, Maciej S. Szmigiero wrote:
    > On 28.05.2021 21:11, Paolo Bonzini wrote:
    >> The memory that is allocated in vm_create is already mapped close to
    >> GPA 0, because test_execute passes the requested memory to
    >> prepare_vm.  This causes overlapping memory regions and the
    >> test crashes.  For simplicity just move MEM_GPA higher.
    >>
    >> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
    >
    > I am not sure that I understand the issue correctly, is vm_create_default()
    > already reserving low GPAs (around 0x10000000) on some arches or run
    > environments?

    It maps the number of pages you pass in the second argument, see
    vm_create.

    if (phy_pages != 0)
    vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
    0, 0, phy_pages, 0);

    In this case:

    data->vm = vm_create_default(VCPU_ID, mempages, guest_code);

    called here:

    if (!prepare_vm(data, nslots, maxslots, tdata->guest_code,
    mem_size, slot_runtime)) {

    where mempages is mem_size, which is declared as:

    uint64_t mem_size = tdata->mem_size ? : MEM_SIZE_PAGES;

    but actually a better fix is just to pass a small fixed value (e.g.
    1024) to vm_create_default, since all other regions are added by hand.

    Paolo

    \
     
     \ /
      Last update: 2021-05-29 12:21    [W:6.985 / U:0.824 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site