2017-02-28 13:07-0800, Jim Mattson: > I believe this happens when the VMCS12 MSR bitmap address is valid, > but no device is configured to respond to the bus request. I agree > that the warning should be removed. However, in this case, the VMCS12 > MSR bitmap should read as all 1s. The same is true everywhere that > nested_get_page returns NULL. Reads should return all 1s and writes > should be ignored. Yes, we have already checked that the address is within physical limits and page-aligned. After that, any errors seem like undefined behavior. Going to do a bare-metal check and send a patch, thanks. > On Tue, Feb 28, 2017 at 11:06 AM, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote: >> >> ------------[ cut here ]------------ >> WARNING: CPU: 0 PID: 7832 at arch/x86/kvm/vmx.c:9709 >> warn_slowpath_null+0x2c/0x40 kernel/panic.c:583 >> nested_vmx_merge_msr_bitmap arch/x86/kvm/vmx.c:9709 [inline] >> nested_get_vmcs12_pages+0xfb6/0x15c0 arch/x86/kvm/vmx.c:9640 >> enter_vmx_non_root_mode arch/x86/kvm/vmx.c:10471 [inline] >> nested_vmx_run+0x6186/0xaab0 arch/x86/kvm/vmx.c:10561 >> >> If I am reading this correctly, failure to map msr bitmap is trivially >> trigger-able by guest (specify an invalid address?) and thus should >> not be a warning. The case is already handled by disabling >> acceleration. So can we remove the warning? or replace with pr_err?
