Re: [Xen-devel] [RFC XEN PATCH 02/16] x86_64/mm: explicitly specify the location to place the M2P table

[Haozhong Zhang <haozhong.zhang@xxxxxxxxx>]

On 12/09/16 16:38 -0500, Konrad Rzeszutek Wilk wrote:
> On Mon, Oct 10, 2016 at 08:32:21AM +0800, Haozhong Zhang wrote:
> > A reserved area on each pmem region is used to place the M2P table.
> > However, it's not at the beginning of the pmem region, so we need to
> > specify the location explicitly when creating the M2P table.
> >
> > Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>
> > ---
> > Cc: Jan Beulich <jbeulich@xxxxxxxx>
> > Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> > ---
> >  xen/arch/x86/x86_64/mm.c | 14 ++++++++------
> >  1 file changed, 8 insertions(+), 6 deletions(-)
> >
> > diff --git a/xen/arch/x86/x86_64/mm.c b/xen/arch/x86/x86_64/mm.c
> > index 33f226a..5c0f527 100644
> > --- a/xen/arch/x86/x86_64/mm.c
> > +++ b/xen/arch/x86/x86_64/mm.c
> > @@ -317,7 +317,8 @@ void destroy_m2p_mapping(struct mem_hotadd_info *info)
> >   * spfn/epfn: the pfn ranges to be setup
> >   * free_s/free_e: the pfn ranges that is free still
> >   */
> > -static int setup_compat_m2p_table(struct mem_hotadd_info *info)
> > +static int setup_compat_m2p_table(struct mem_hotadd_info *info,
> > +                                  struct mem_hotadd_info *alloc_info)
> >  {
> >      unsigned long i, va, smap, emap, rwva, epfn = info->epfn, mfn;
> >      unsigned int n;
> > @@ -371,7 +372,7 @@ static int setup_compat_m2p_table(struct mem_hotadd_info 
> > *info)
> >          if ( n == CNT )
> >              continue;
> >
> > -        mfn = alloc_hotadd_mfn(info);
> > +        mfn = alloc_hotadd_mfn(alloc_info);
> >          err = map_pages_to_xen(rwva, mfn, 1UL << PAGETABLE_ORDER,
> >                                 PAGE_HYPERVISOR);
> >          if ( err )
> > @@ -391,7 +392,8 @@ static int setup_compat_m2p_table(struct mem_hotadd_info 
> > *info)
> >   * Allocate and map the machine-to-phys table.
> >   * The L3 for RO/RWRW MPT and the L2 for compatible MPT should be setup already
> >   */
> > -static int setup_m2p_table(struct mem_hotadd_info *info)
> > +static int setup_m2p_table(struct mem_hotadd_info *info,
> > +                           struct mem_hotadd_info *alloc_info)
> >  {
> >      unsigned long i, va, smap, emap;
> >      unsigned int n;
> > @@ -440,7 +442,7 @@ static int setup_m2p_table(struct mem_hotadd_info *info)
> >                  break;
> >          if ( n < CNT )
> >          {
> > -            unsigned long mfn = alloc_hotadd_mfn(info);
> > +            unsigned long mfn = alloc_hotadd_mfn(alloc_info);
> >
> >              ret = map_pages_to_xen(
> >                          RDWR_MPT_VIRT_START + i * sizeof(unsigned long),
> > @@ -485,7 +487,7 @@ static int setup_m2p_table(struct mem_hotadd_info *info)
> >  #undef CNT
> >  #undef MFN
> >
> > -    ret = setup_compat_m2p_table(info);
> > +    ret = setup_compat_m2p_table(info, alloc_info);
> >  error:
> >      return ret;
> >  }
> > @@ -1427,7 +1429,7 @@ int memory_add(unsigned long spfn, unsigned long epfn, 
> > unsigned int pxm)
> >      total_pages += epfn - spfn;
> >
> >      set_pdx_range(spfn, epfn);
> > -    ret = setup_m2p_table(&info);
> > +    ret = setup_m2p_table(&info, &info);
> I am not sure I follow this logic. You are passing the same contents, it
> is just that 'alloc_info' and 'info' are aliased together?
Similarly to patch 1, the two parameters of setup_m2p_table() are
identical for the ordinary RAM, and can be different for NVDIMM.

Haozhong

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