Re: [PATCH RFC 1/3] x86/kvm/vmx: read MSR_FS_BASE from current->thread

[Vitaly Kuznetsov]

Andy Lutomirski <luto@xxxxxxxxxx> writes:

> On Fri, Mar 2, 2018 at 10:55 AM, Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> wrote:
>> vmx_save_host_state() is only called from kvm_arch_vcpu_ioctl_run() so
>> the context is pretty well defined
>>
>
> True.
>
>> and MSR_FS_BASE should always be
>> equal to current->thread.fsbase.
>
> Not true.  current->thread.fsbase is almost entirely undefined in this
> context.  What you *could* do is export save_fsgs() and call it first.
> When FSGSBASE support lands (which will happen eventually!), the code
> in your patch will be completely wrong.
>
> Admittedly, your patch isn't 100% bogus, but the reason is subtle and
> you need lots of comments there *and* in save_fsgs().

Thank you Andy,

I'll take a look.

-- 
  Vitaly