Re: [PATCH v2] doc: kvm: Fix return description of KVM_SET_MSRS

[Xiaoyao Li]

On 9/5/2019 1:41 AM, Sean Christopherson wrote:
> On Wed, Sep 04, 2019 at 02:01:18PM +0800, Xiaoyao Li wrote:
> > Userspace can use ioctl KVM_SET_MSRS to update a set of MSRs of guest.
> > This ioctl sets specified MSRs one by one. Once it fails to set an MSR
> > due to setting reserved bits, the MSR is not supported/emulated by kvm,
> > or violating other restrictions, it stops further processing and returns
> > the number of MSRs have been set successfully.
> >
> > Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
> > ---
> > v2:
> >    elaborate the changelog and description of ioctl KVM_SET_MSRS based on
> >    Sean's comments.
> >
> > ---
> >   Documentation/virt/kvm/api.txt | 7 ++++++-
> >   1 file changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/Documentation/virt/kvm/api.txt b/Documentation/virt/kvm/api.txt
> > index 2d067767b617..4638e893dec0 100644
> > --- a/Documentation/virt/kvm/api.txt
> > +++ b/Documentation/virt/kvm/api.txt
> > @@ -586,7 +586,7 @@ Capability: basic
> >   Architectures: x86
> >   Type: vcpu ioctl
> >   Parameters: struct kvm_msrs (in)
> > -Returns: 0 on success, -1 on error
> > +Returns: number of msrs successfully set (see below), -1 on error
> >   
> >   Writes model-specific registers to the vcpu.  See KVM_GET_MSRS for the
> >   data structures.
> > @@ -595,6 +595,11 @@ Application code should set the 'nmsrs' member (which indicates the
> >   size of the entries array), and the 'index' and 'data' members of each
> >   array entry.
> >   
> > +It tries to set the MSRs in array entries[] one by one. Once failing to
>
> Probably better to say 'If' as opposed to 'Once', don't want to imply that
> userspace is incompetent :)
>
> > +set an MSR (due to setting reserved bits, the MSR is not supported/emulated
> > +by kvm, or violating other restrctions),
>
> Make it clear the list is not exhaustive, e.g.:
>
> It tries to set the MSRs in array entries[] one by one.  If setting an MSR
> fails, e.g. due to setting reserved bits, the MSR isn't supported/emulated by
> KVM, etc..., it stops processing the MSR list and returns the number of MSRs
> that have been set successfully.

Refine it as you commented and send out v3, thanks.

> > it stops setting following MSRs
> > +and returns the number of MSRs have been set successfully.
> > +
> >   
> >   4.20 KVM_SET_CPUID
> >   
> > --
> > 2.19.1