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Re: [Xen-devel] [PATCH] Handle broken page with regard to migration



On Fri, Nov 2, 2012 at 3:25 AM, Liu Jinsong <jinsong.liu@xxxxxxxxx> wrote:
> Generally, there are 2 cases:
> 1. broken page occurs before migration
> 2. broken page occurs during migration
>
> At the sender
>   for case 1, the broken page would be mapped but not copied to target
>   (otherwise it may trigger more serious error, say, SRAR error).
>   While its pfn_type and pfn number would be transferred to target
>   so that target take appropriate action.
>
>   for case 2, mce handler marks the broken page to dirty bitmap, so that
>   at copypages stage of migration, its pfn_type and pfn number would be
>   transferred to target and then take appropriate action.
>
> At the target
>   it would set p2m as p2m_ram_broken for broken page, so that if guest
>   access the broken page again, it would kill itself as expected.
>
> Suggested-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
> Signed-off-by: Liu, Jinsong <jinsong.liu@xxxxxxxxx>

Looks good to me -- thanks, Jinsong!

Acked-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>

>
> diff -r d675797494bd -r 730dd3f22a12 tools/libxc/xc_domain.c
> --- a/tools/libxc/xc_domain.c   Fri Nov 02 11:08:37 2012 +0800
> +++ b/tools/libxc/xc_domain.c   Fri Nov 02 11:08:37 2012 +0800
> @@ -283,6 +283,22 @@
>      return ret;
>  }
>
> +/* set broken page p2m */
> +int xc_set_broken_page_p2m(xc_interface *xch,
> +                           uint32_t domid,
> +                           unsigned long pfn)
> +{
> +    int ret;
> +    DECLARE_DOMCTL;
> +
> +    domctl.cmd = XEN_DOMCTL_set_broken_page_p2m;
> +    domctl.domain = (domid_t)domid;
> +    domctl.u.set_broken_page_p2m.pfn = pfn;
> +    ret = do_domctl(xch, &domctl);
> +
> +    return ret ? -1 : 0;
> +}
> +
>  /* get info from hvm guest for save */
>  int xc_domain_hvm_getcontext(xc_interface *xch,
>                               uint32_t domid,
> diff -r d675797494bd -r 730dd3f22a12 tools/libxc/xc_domain_restore.c
> --- a/tools/libxc/xc_domain_restore.c   Fri Nov 02 11:08:37 2012 +0800
> +++ b/tools/libxc/xc_domain_restore.c   Fri Nov 02 11:08:37 2012 +0800
> @@ -962,9 +962,15 @@
>
>      countpages = count;
>      for (i = oldcount; i < buf->nr_pages; ++i)
> -        if ((buf->pfn_types[i] & XEN_DOMCTL_PFINFO_LTAB_MASK) == 
> XEN_DOMCTL_PFINFO_XTAB
> -            ||(buf->pfn_types[i] & XEN_DOMCTL_PFINFO_LTAB_MASK) == 
> XEN_DOMCTL_PFINFO_XALLOC)
> +    {
> +        unsigned long pagetype;
> +
> +        pagetype = buf->pfn_types[i] & XEN_DOMCTL_PFINFO_LTAB_MASK;
> +        if ( pagetype == XEN_DOMCTL_PFINFO_XTAB ||
> +             pagetype == XEN_DOMCTL_PFINFO_BROKEN ||
> +             pagetype == XEN_DOMCTL_PFINFO_XALLOC )
>              --countpages;
> +    }
>
>      if (!countpages)
>          return count;
> @@ -1200,6 +1206,17 @@
>              /* a bogus/unmapped/allocate-only page: skip it */
>              continue;
>
> +        if ( pagetype == XEN_DOMCTL_PFINFO_BROKEN )
> +        {
> +            if ( xc_set_broken_page_p2m(xch, dom, pfn) )
> +            {
> +                ERROR("Set p2m for broken page failed, "
> +                      "dom=%d, pfn=%lx\n", dom, pfn);
> +                goto err_mapped;
> +            }
> +            continue;
> +        }
> +
>          if (pfn_err[i])
>          {
>              ERROR("unexpected PFN mapping failure pfn %lx map_mfn %lx 
> p2m_mfn %lx",
> diff -r d675797494bd -r 730dd3f22a12 tools/libxc/xc_domain_save.c
> --- a/tools/libxc/xc_domain_save.c      Fri Nov 02 11:08:37 2012 +0800
> +++ b/tools/libxc/xc_domain_save.c      Fri Nov 02 11:08:37 2012 +0800
> @@ -1277,6 +1277,13 @@
>                  if ( !hvm )
>                      gmfn = pfn_to_mfn(gmfn);
>
> +                if ( pfn_type[j] == XEN_DOMCTL_PFINFO_BROKEN )
> +                {
> +                    pfn_type[j] |= pfn_batch[j];
> +                    ++run;
> +                    continue;
> +                }
> +
>                  if ( pfn_err[j] )
>                  {
>                      if ( pfn_type[j] == XEN_DOMCTL_PFINFO_XTAB )
> @@ -1371,8 +1378,12 @@
>                      }
>                  }
>
> -                /* skip pages that aren't present or are alloc-only */
> +                /*
> +                 * skip pages that aren't present,
> +                 * or are broken, or are alloc-only
> +                 */
>                  if ( pagetype == XEN_DOMCTL_PFINFO_XTAB
> +                    || pagetype == XEN_DOMCTL_PFINFO_BROKEN
>                      || pagetype == XEN_DOMCTL_PFINFO_XALLOC )
>                      continue;
>
> diff -r d675797494bd -r 730dd3f22a12 tools/libxc/xenctrl.h
> --- a/tools/libxc/xenctrl.h     Fri Nov 02 11:08:37 2012 +0800
> +++ b/tools/libxc/xenctrl.h     Fri Nov 02 11:08:37 2012 +0800
> @@ -575,6 +575,17 @@
>                            xc_domaininfo_t *info);
>
>  /**
> + * This function set p2m for broken page
> + * &parm xch a handle to an open hypervisor interface
> + * @parm domid the domain id which broken page belong to
> + * @parm pfn the pfn number of the broken page
> + * @return 0 on success, -1 on failure
> + */
> +int xc_set_broken_page_p2m(xc_interface *xch,
> +                           uint32_t domid,
> +                           unsigned long pfn);
> +
> +/**
>   * This function returns information about the context of a hvm domain
>   * @parm xch a handle to an open hypervisor interface
>   * @parm domid the domain to get information from
> diff -r d675797494bd -r 730dd3f22a12 xen/arch/x86/cpu/mcheck/mcaction.c
> --- a/xen/arch/x86/cpu/mcheck/mcaction.c        Fri Nov 02 11:08:37 2012 +0800
> +++ b/xen/arch/x86/cpu/mcheck/mcaction.c        Fri Nov 02 11:08:37 2012 +0800
> @@ -1,5 +1,6 @@
>  #include <xen/types.h>
>  #include <xen/sched.h>
> +#include <asm/p2m.h>
>  #include "mcaction.h"
>  #include "vmce.h"
>  #include "mce.h"
> @@ -91,6 +92,24 @@
>                      goto vmce_failed;
>                  }
>
> +                if ( is_hvm_domain(d) && !d->arch.hvm_domain.dirty_vram &&
> +                     paging_mode_log_dirty(d) )
> +                {
> +                    /*
> +                     * vMCE occur during migration
> +                     *
> +                     *   At sender, it marks broken page to dirty bitmap,
> +                     *   so that at copypages stage of migration, brokan
> +                     *   page's pfn_type and pfn number would be transferred
> +                     *   to target and then take appropriate action.
> +                     *
> +                     *   At target, it would set p2m as p2m_ram_broken for
> +                     *   broken page, so that if guest access the broken page
> +                     *   again, it would kill itself as expected.
> +                     */
> +                    paging_mark_dirty(d, mfn);
> +                }
> +
>                  if ( unmmap_broken_page(d, _mfn(mfn), gfn) )
>                  {
>                      printk("Unmap broken memory %lx for DOM%d failed\n",
> diff -r d675797494bd -r 730dd3f22a12 xen/arch/x86/domctl.c
> --- a/xen/arch/x86/domctl.c     Fri Nov 02 11:08:37 2012 +0800
> +++ b/xen/arch/x86/domctl.c     Fri Nov 02 11:08:37 2012 +0800
> @@ -209,12 +209,18 @@
>                  for ( j = 0; j < k; j++ )
>                  {
>                      unsigned long type = 0;
> +                    p2m_type_t t;
>
> -                    page = get_page_from_gfn(d, arr[j], NULL, P2M_ALLOC);
> +                    page = get_page_from_gfn(d, arr[j], &t, P2M_ALLOC);
>
>                      if ( unlikely(!page) ||
>                           unlikely(is_xen_heap_page(page)) )
> -                        type = XEN_DOMCTL_PFINFO_XTAB;
> +                    {
> +                        if ( p2m_is_broken(t) )
> +                            type = XEN_DOMCTL_PFINFO_BROKEN;
> +                        else
> +                            type = XEN_DOMCTL_PFINFO_XTAB;
> +                    }
>                      else
>                      {
>                          switch( page->u.inuse.type_info & PGT_type_mask )
> @@ -235,6 +241,9 @@
>
>                          if ( page->u.inuse.type_info & PGT_pinned )
>                              type |= XEN_DOMCTL_PFINFO_LPINTAB;
> +
> +                        if ( page->count_info & PGC_broken )
> +                            type = XEN_DOMCTL_PFINFO_BROKEN;
>                      }
>
>                      if ( page )
> @@ -1568,6 +1577,29 @@
>      }
>      break;
>
> +    case XEN_DOMCTL_set_broken_page_p2m:
> +    {
> +        struct domain *d;
> +
> +        d = rcu_lock_domain_by_id(domctl->domain);
> +        if ( d != NULL )
> +        {
> +            p2m_type_t pt;
> +            unsigned long pfn = domctl->u.set_broken_page_p2m.pfn;
> +            mfn_t mfn = get_gfn_query(d, pfn, &pt);
> +
> +            if ( unlikely(!mfn_valid(mfn_x(mfn)) || !p2m_is_ram(pt) ||
> +                         (p2m_change_type(d, pfn, pt, p2m_ram_broken) != 
> pt)) )
> +                ret = -EINVAL;
> +
> +            put_gfn(d, pfn);
> +            rcu_unlock_domain(d);
> +        }
> +        else
> +            ret = -ESRCH;
> +    }
> +    break;
> +
>      default:
>          ret = iommu_do_domctl(domctl, u_domctl);
>          break;
> diff -r d675797494bd -r 730dd3f22a12 xen/include/public/domctl.h
> --- a/xen/include/public/domctl.h       Fri Nov 02 11:08:37 2012 +0800
> +++ b/xen/include/public/domctl.h       Fri Nov 02 11:08:37 2012 +0800
> @@ -136,6 +136,7 @@
>  #define XEN_DOMCTL_PFINFO_LPINTAB (0x1U<<31)
>  #define XEN_DOMCTL_PFINFO_XTAB    (0xfU<<28) /* invalid page */
>  #define XEN_DOMCTL_PFINFO_XALLOC  (0xeU<<28) /* allocate-only page */
> +#define XEN_DOMCTL_PFINFO_BROKEN  (0xdU<<28) /* broken page */
>  #define XEN_DOMCTL_PFINFO_PAGEDTAB (0x8U<<28)
>  #define XEN_DOMCTL_PFINFO_LTAB_MASK (0xfU<<28)
>
> @@ -835,6 +836,12 @@
>  typedef struct xen_domctl_set_access_required 
> xen_domctl_set_access_required_t;
>  DEFINE_XEN_GUEST_HANDLE(xen_domctl_set_access_required_t);
>
> +struct xen_domctl_set_broken_page_p2m {
> +    uint64_aligned_t pfn;
> +};
> +typedef struct xen_domctl_set_broken_page_p2m 
> xen_domctl_set_broken_page_p2m_t;
> +DEFINE_XEN_GUEST_HANDLE(xen_domctl_set_broken_page_p2m_t);
> +
>  struct xen_domctl {
>      uint32_t cmd;
>  #define XEN_DOMCTL_createdomain                   1
> @@ -900,6 +907,7 @@
>  #define XEN_DOMCTL_set_access_required           64
>  #define XEN_DOMCTL_audit_p2m                     65
>  #define XEN_DOMCTL_set_virq_handler              66
> +#define XEN_DOMCTL_set_broken_page_p2m           67
>  #define XEN_DOMCTL_gdbsx_guestmemio            1000
>  #define XEN_DOMCTL_gdbsx_pausevcpu             1001
>  #define XEN_DOMCTL_gdbsx_unpausevcpu           1002
> @@ -955,6 +963,7 @@
>          struct xen_domctl_audit_p2m         audit_p2m;
>          struct xen_domctl_set_virq_handler  set_virq_handler;
>          struct xen_domctl_gdbsx_memio       gdbsx_guest_memio;
> +        struct xen_domctl_set_broken_page_p2m set_broken_page_p2m;
>          struct xen_domctl_gdbsx_pauseunp_vcpu gdbsx_pauseunp_vcpu;
>          struct xen_domctl_gdbsx_domstatus   gdbsx_domstatus;
>          uint8_t                             pad[128];
>
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> http://lists.xen.org/xen-devel

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