Re: [Xen-devel] [PATCH] don't save Xen heap pages during domain save

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

I've applied all your patches as of xen-unstable:21621. Are they all
suitable for Xen 4.0.x do you think? What about 3.4.x?

 Thanks,
 Keir

On 15/06/2010 12:45, "Jan Beulich" <JBeulich@xxxxxxxxxx> wrote:

> As discussed in the thread starting at
> http://lists.xensource.com/archives/html/xen-devel/2010-05/msg01383.html,
> don't save Xen heap pages in order to avoid overallocation when the
> domain gets restored, as those pages would get (temporarily) backed
> with normal RAM pages by the restore code.
> 
> This requires making DOMCTL_getpageframeinfo{2,3} usable for HVM guests,
> meaning that the input to these must be treated as GMFNs.
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
> 
> --- 2010-06-15.orig/tools/libxc/xc_domain_save.c 2010-06-01 13:39:57.000000000
> +0200
> +++ 2010-06-15/tools/libxc/xc_domain_save.c 2010-06-15 09:32:42.000000000
> +0200
> @@ -1288,58 +1288,64 @@ int xc_domain_save(xc_interface *xch, in
>                  goto out;
>              }
>  
> -            if ( hvm )
> +            /* Get page types */
> +            if ( xc_get_pfn_type_batch(xch, dom, batch, pfn_type) )
>              {
> -                /* Look for and skip completely empty batches. */
> -                for ( j = 0; j < batch; j++ )
> -                {
> -                    if ( !pfn_err[j] )
> -                        break;
> -                    pfn_type[j] |= XEN_DOMCTL_PFINFO_XTAB;
> -                }
> -                if ( j == batch )
> -                {
> -                    munmap(region_base, batch*PAGE_SIZE);
> -                    continue; /* bail on this batch: no valid pages */
> -                }
> -                for ( ; j < batch; j++ )
> -                    if ( pfn_err[j] )
> -                        pfn_type[j] |= XEN_DOMCTL_PFINFO_XTAB;
> +                PERROR("get_pfn_type_batch failed");
> +                goto out;
>              }
> -            else
> +
> +            for ( run = j = 0; j < batch; j++ )
>              {
> -                /* Get page types */
> -                if ( xc_get_pfn_type_batch(xch, dom, batch, pfn_type) )
> -                {
> -                    PERROR("get_pfn_type_batch failed");
> -                    goto out;
> -                }
> +                unsigned long gmfn = pfn_batch[j];
>  
> -                for ( j = 0; j < batch; j++ )
> +                if ( !hvm )
> +                    gmfn = pfn_to_mfn(gmfn);
> +
> +                if ( pfn_err[j] )
>                  {
> -                    unsigned long mfn = pfn_to_mfn(pfn_batch[j]);
> -                
>                      if ( pfn_type[j] == XEN_DOMCTL_PFINFO_XTAB )
> -                    {
> -                        DPRINTF("type fail: page %i mfn %08lx\n",
> -                                j, mfn);
>                          continue;
> -                    }
> -                
> -                    if ( debug )
> +                    DPRINTF("map fail: page %i mfn %08lx err %d\n",
> +                            j, gmfn, pfn_err[j]);
> +                    pfn_type[j] = XEN_DOMCTL_PFINFO_XTAB;
> +                    continue;
> +                }
> +
> +                if ( pfn_type[j] == XEN_DOMCTL_PFINFO_XTAB )
> +                {
> +                    DPRINTF("type fail: page %i mfn %08lx\n", j, gmfn);
> +                    continue;
> +                }
> +
> +                /* canonicalise mfn->pfn */
> +                pfn_type[j] |= pfn_batch[j];
> +                ++run;
> +
> +                if ( debug )
> +                {
> +                    if ( hvm )
> +                        DPRINTF("%d pfn=%08lx sum=%08lx\n",
> +                                iter,
> +                                pfn_type[j],
> +                                csum_page(region_base + (PAGE_SIZE*j)));
> +                    else
>                          DPRINTF("%d pfn= %08lx mfn= %08lx [mfn]= %08lx"
>                                  " sum= %08lx\n",
>                                  iter,
> -                                pfn_type[j] | pfn_batch[j],
> -                                mfn,
> -                                mfn_to_pfn(mfn),
> +                                pfn_type[j],
> +                                gmfn,
> +                                mfn_to_pfn(gmfn),
>                                  csum_page(region_base + (PAGE_SIZE*j)));
> -                
> -                    /* canonicalise mfn->pfn */
> -                    pfn_type[j] |= pfn_batch[j];
>                  }
>              }
>  
> +            if ( !run )
> +            {
> +                munmap(region_base, batch*PAGE_SIZE);
> +                continue; /* bail on this batch: no valid pages */
> +            }
> +
>              if ( wrexact(io_fd, &batch, sizeof(unsigned int)) )
>              {
>                  PERROR("Error when writing to state file (2)");
> --- 2010-06-15.orig/xen/arch/x86/domctl.c 2010-03-02 09:11:28.000000000 +0100
> +++ 2010-06-15/xen/arch/x86/domctl.c 2010-06-15 09:32:42.000000000 +0200
> @@ -207,11 +207,12 @@ long arch_do_domctl(
>  
>                  for ( j = 0; j < k; j++ )
>                  {
> -                    unsigned long type = 0, mfn = arr[j];
> +                    unsigned long type = 0, mfn = gmfn_to_mfn(d, arr[j]);
>  
>                      page = mfn_to_page(mfn);
>  
> -                    if ( unlikely(!mfn_valid(mfn)) )
> +                    if ( unlikely(!mfn_valid(mfn)) ||
> +                         unlikely(is_xen_heap_mfn(mfn)) )
>                          type = XEN_DOMCTL_PFINFO_XTAB;
>                      else if ( xsm_getpageframeinfo(page) != 0 )
>                          ;
> @@ -306,14 +307,15 @@ long arch_do_domctl(
>              for ( j = 0; j < k; j++ )
>              {   
>                  struct page_info *page;
> -                unsigned long mfn = arr32[j];
> +                unsigned long mfn = gmfn_to_mfn(d, arr32[j]);
>  
>                  page = mfn_to_page(mfn);
>  
>                  if ( domctl->cmd == XEN_DOMCTL_getpageframeinfo3)
>                      arr32[j] = 0;
>  
> -                if ( unlikely(!mfn_valid(mfn)) )
> +                if ( unlikely(!mfn_valid(mfn)) ||
> +                     unlikely(is_xen_heap_mfn(mfn)) )
>                      arr32[j] |= XEN_DOMCTL_PFINFO_XTAB;
>                  else if ( xsm_getpageframeinfo(page) != 0 )
>                      continue;
> 
> 



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