Re: [PATCH 04/16] vmx: nest: nested control structure

[Christoph Egger <Christoph.Egger@amd.com>]

On Wednesday 15 September 2010 15:06:03 Dong, Eddie wrote:
> Christoph Egger wrote:
> > On Wednesday 08 September 2010 17:22:12 Qing He wrote:
> >> v->arch.hvm_vmx.nest as control structure
> >>
> >> Signed-off-by: Qing He <qing.he@intel.com>
> >> Signed-off-by: Eddie Dong <eddie.dong@intel.com>
> >>
> >> ---
> >> diff -r fc4de5eedd1d xen/include/asm-x86/hvm/vmx/nest.h
> >> --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
> >> +++ b/xen/include/asm-x86/hvm/vmx/nest.h	Wed Sep 08 21:03:41 2010
> >> +0800 @@ -0,0 +1,45 @@ +/*
> >> + * nest.h: nested virtualization for VMX.
> >> + *
> >> + * Copyright (c) 2010, Intel Corporation.
> >> + * Author: Qing He <qing.he@intel.com>
> >> + *
> >> + * This program is free software; you can redistribute it and/or
> >> modify it + * under the terms and conditions of the GNU General
> >> Public License, + * version 2, as published by the Free Software
> >> Foundation. + * + * This program is distributed in the hope it will
> >> be useful, but WITHOUT + * ANY WARRANTY; without even the implied
> >> warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE.
> >> See the GNU General Public License for + * more details. + *
> >> + * You should have received a copy of the GNU General Public
> >> License along with + * this program; if not, write to the Free
> >> Software Foundation, Inc., 59 Temple + * Place - Suite 330, Boston,
> >> MA 02111-1307 USA. + * + */
> >> +#ifndef __ASM_X86_HVM_NEST_H__
> >> +#define __ASM_X86_HVM_NEST_H__
> >> +
> >> +struct vmcs_struct;
> >> +
> >> +struct vmx_nest_struct {
> >
> > Is it ok to name it 'struct nestedvmx' ?
>
> Fine, renamed to nested_vmx.
>
> >> +    paddr_t              guest_vmxon_pa;
> >> +
> >> +    /* Saved host vmcs for vcpu itself */
> >> +    struct vmcs_struct  *hvmcs;
> >> +
> >> +    /*
> >> +     * Guest's `current vmcs' of vcpu
> >> +     *  - gvmcs_pa: guest VMCS region physical address
> >> +     *  - vvmcs:    (guest) virtual vmcs
> >> +     *  - svmcs:    effective vmcs for the guest of this vcpu
> >> +     *  - valid:    launch state: invalid on clear, valid on ld +
> >> */ +    paddr_t              gvmcs_pa;
> >> +    void                *vvmcs;
> >> +    struct vmcs_struct  *svmcs;
> >> +    int                  vmcs_valid;
> >> +};
> >> +
> >> +#endif /* __ASM_X86_HVM_NEST_H__ */
> >> diff -r fc4de5eedd1d xen/include/asm-x86/hvm/vmx/vmcs.h
> >> --- a/xen/include/asm-x86/hvm/vmx/vmcs.h	Wed Sep 08 21:00:00 2010
> >> +0800 +++ b/xen/include/asm-x86/hvm/vmx/vmcs.h	Wed Sep 08 21:03:41
> >>  2010 +0800 @@ -22,6 +22,7 @@ #include <asm/config.h>
> >>  #include <asm/hvm/io.h>
> >>  #include <asm/hvm/vpmu.h>
> >> +#include <asm/hvm/vmx/nest.h>
> >>
> >>  extern void vmcs_dump_vcpu(struct vcpu *v);
> >>  extern void setup_vmcs_dump(void);
> >> @@ -99,6 +100,9 @@
> >>      u32                  secondary_exec_control;
> >>      u32                  exception_bitmap;
> >>
> >> +    /* nested virtualization */
> >> +    struct vmx_nest_struct nest;
> >> +
> >>  #ifdef __x86_64__
> >>      struct vmx_msr_state msr_state;
> >>      unsigned long        shadow_gs;
> >
> > I think, the structure should be allocated in the
> > nestedhvm_vcpu_initialise() function hook and assigned to the nh_arch
> > pointer in struct nestedhvm.
>
> Well, the structure itself is pretty small, so dynamic allocation is really
> not a good idea. Instead, the internal field such as vvmcs/svmcs are big
> and thus we use a pointer, but they are allocated on demand. This follows
> the style of arch_vmx_struct in vcpu data structure.
>
> I am fine with your nestedhvm_vcpu_initialise "design", but VMX doesn't
> need to use the wrapper so far.

It should be implemented good enough that vcpu creation doesn't fail.

Christoph


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