Re: [Xen-devel] [PATCH v5 0/4] nested vmx: enable VMCS shadowing feature

["Xu, Dongxiao" <dongxiao.xu@xxxxxxxxx>]

> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: Wednesday, January 23, 2013 10:31 PM
> To: Xu, Dongxiao
> Cc: Dong, Eddie; Nakajima, Jun; Zhang, Xiantao; xen-devel
> Subject: Re: [PATCH v5 0/4] nested vmx: enable VMCS shadowing feature
> 
> >>> On 23.01.13 at 09:39, Dongxiao Xu <dongxiao.xu@xxxxxxxxx> wrote:
> > Changes from v4 to v5:
> >  - Change the size for vvmcs buffer from 500 to 100.
> >  - Store page_info in per-pCPU structure instead of MFN in per-vCPU
> structure
> > for vmread/vmwrite bitmaps.
> >  - Define correct data type to avoid force type conversion.
> 
> Looks good to me now, so I guess all that's needed is an ack from
> Jun or Eddie, and a check of yours that this still applies to the tip of
> the staging tree.

Thanks!
I checked the latest staging tree, and there is a tiny conflict, I will fix it 
and re-send them out.

Thanks,
Dongxiao

> 
> Jan
> 
> > Changes from v3 to v4:
> >  - Allocate a buffer in initialization time for data exchange instead of
> > runtime allocation (reflect Jun's comment).
> >  - Move the vmread/vmwrite bitmap logic into nvmx_vcpu_initialise(), also
> > track MFN instead of virtual address in the vcpu global data. (reflect Jan's
> > comment).
> >
> > Changes from v2 to v3:
> >  - Use pfn_to_paddr() to get the address from frame number instead of
> doing
> > shift directly.
> >  - Remove some unnecessary initialization code and add "static" to
> > vmentry_fields and gpdptr_fields.
> >  - Enable the VMREAD/VMWRITE bitmap only if nested hvm is enabled.
> >  - Use clear_page() to set all 0 to the page instead of memset().
> >  - Use domheap to allocate the VMREAD/VMWRITE bitmap instead of
> xenheap.
> >
> > Changes from v1 to v2:
> >  - Use domain_page_map_to_mfn() instead of virt_to_mfn() to get the
> machine
> > frame.
> >  - Address other comments from Jan, including some programming format,
> return
> > value type, etc.
> >
> > Latest Intel SDM introduced a new feature "VMCS shadowing" at bit 14 in
> > Secondary Processor-Based VM-Execution Controls for nested virtualization.
> >
> > The main purpose of this feature is to reduce or eliminate the number of VM
> > exit
> > for non-root VMREAD and VMWRITE. It provides the capability to link a
> > "virtual VMCS" with the current running VMCS, so that after VM entry, the
> > non-root VMREAD and VMWRITE can get/set related data directly from/to
> the
> > "virtual VMCS" without trap and emulation.
> >
> > A separate bitmap is introduced for VMREAD and VMWRITE, from which
> > hypervisor
> > can control whether VMREAD/VMWRITE from/to certain VMCS field will
> trigger
> > VM exit or directly get/set data by hardware.
> >
> > With the new feature introduced, all the in "virtual VMCS" need to be
> > operated
> > by VMREAD and VMWRITE because this VMCS will also be loaded into
> hardware.
> > This requires the capability to VMWRITE all the VMCS fields, including those
> > readonly ones. Intel SDM introduces this functionality at bit 29 in
> > IA32_VMX_MISC MSR.
> >
> > For details, please refer to:
> >
> http://www.intel.com/content/www/us/en/processors/architectures-software
> -devel
> > oper-manuals.html
> >
> > Thanks,
> > Dongxiao
> >
> > Dongxiao Xu (4):
> >   nested vmx: Use a list to store the launched vvmcs for L1 VMM
> >   nested vmx: use VMREAD/VMWRITE to construct vVMCS if enabled VMCS
> >     shadowing
> >   nested vmx: optimize for bulk access of virtual VMCS
> >   nested vmx: enable VMCS shadowing feature
> >
> >  xen/arch/x86/hvm/vmx/vmcs.c        |   48 ++++++
> >  xen/arch/x86/hvm/vmx/vvmx.c        |  324
> ++++++++++++++++++++++++++++++++----
> >  xen/include/asm-x86/hvm/vmx/vmcs.h |   23 +++-
> >  xen/include/asm-x86/hvm/vmx/vvmx.h |   24 +++-
> >  4 files changed, 383 insertions(+), 36 deletions(-)
> 
> 


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