Re: [Xen-devel] [v2 05/11] vmx: add new data structure member to support PML

[Kai Huang <kai.huang@xxxxxxxxxxxxxxx>]

On 04/17/2015 10:31 AM, Kai Huang wrote:
> On 04/17/2015 06:39 AM, Tian, Kevin wrote:
> > > From: Kai Huang [mailto:kai.huang@xxxxxxxxxxxxxxx]
> > > Sent: Wednesday, April 15, 2015 3:04 PM
> > >
> > > A new 4K page pointer is added to arch_vmx_struct as PML buffer for 
> > > vcpu.
> > > And a
> > > new 'status' field is added to vmx_domain to indicate whether PML is 
> > > enabled
> > > for
> > > the domain or not. The 'status' field also can be used for further 
> > > similiar
> > > purpose.
> > not sure about the last sentence. what's the similar purpose to 
> > "whether PML
> > is enabled"? :-)
> I mean potentially there might be such feature in the future, and I 
> can't give you an example right now. If you are just commenting the 
> description here but fine with the current code, I can remove that 
> last sentence if you like. Or do you suggest to just use a "bool_t 
> pml_enabled"? I am fine with both, but looks there's no objection from 
> others so I intend to keep it as 'unsigned int status', if you agree.
Hi Kevin,

What's your opinion here? Is 'unsigned int status' OK to you?

> > > Note both new members don't have to be initialized to zero 
> > > explicitly as both
> > > vcpu and domain structure are zero-ed when they are created.
> > no initialization in this patch, so why explaining it here?
> OK. Looks it's a common sense to all of you so I'll just remove this 
> sentence.
> > > Signed-off-by: Kai Huang <kai.huang@xxxxxxxxxxxxxxx>
> > > ---
> > >   xen/include/asm-x86/hvm/vmx/vmcs.h | 7 +++++++
> > >   1 file changed, 7 insertions(+)
> > >
> > > diff --git a/xen/include/asm-x86/hvm/vmx/vmcs.h
> > > b/xen/include/asm-x86/hvm/vmx/vmcs.h
> > > index f831a78..2c679ac 100644
> > > --- a/xen/include/asm-x86/hvm/vmx/vmcs.h
> > > +++ b/xen/include/asm-x86/hvm/vmx/vmcs.h
> > > @@ -70,8 +70,12 @@ struct ept_data {
> > >       cpumask_var_t synced_mask;
> > >   };
> > >
> > > +#define _VMX_DOMAIN_PML_ENABLED    0
> > > +#define VMX_DOMAIN_PML_ENABLED     (1ul <<
> > > _VMX_DOMAIN_PML_ENABLED)
> > >   struct vmx_domain {
> > >       unsigned long apic_access_mfn;
> > > +    /* VMX_DOMAIN_* */
> > > +    unsigned long status;
> > >   };
> > >
> > >   struct pi_desc {
> > > @@ -142,6 +146,9 @@ struct arch_vmx_struct {
> > >       /* Bitmap to control vmexit policy for Non-root VMREAD/VMWRITE */
> > >       struct page_info     *vmread_bitmap;
> > >       struct page_info     *vmwrite_bitmap;
> > > +
> > > +#define NR_PML_ENTRIES   512
> > > +    struct page_info     *pml_pg;
> > move the macro out of the structure.
> OK. I will move it just above the declaration of struct arch_vmx_struct.
>
> > and is pml_buffer or pml_buf more clear?
> To me pml_buffer or pml_buf is more likely a virtual address you can 
> access the buffer directly, while pml_pg indicates it's a pointer of 
> struct page_info. If you you look at patch 6, you can find statements 
> like:
>     uint64_t *pml_buf;
>
>     pml_buf = __map_domain_page(v->arch.hvm_vmx.pml_pg);
>
> So I intend to keep it.
And this one? Are you OK with 'pml_pg'?

Thanks,
-Kai
> Thanks,
> -Kai
> > >   };
> > >
> > >   int vmx_create_vmcs(struct vcpu *v);
> > > --
> > > 2.1.0
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> > http://lists.xen.org/xen-devel
>
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