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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH V2] X86/vMCE: handle broken page with regard to migration
On Thu, 2012-11-15 at 01:52 +0000, Liu Jinsong 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
Do you mean "will be mapped"? "would be" is past tense which suggests it
was the behaviour before this patch, which I don't think is what you
meant (here and elsewhere in the commit message).
> (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.
What happens if the page is marked broken during the final pass?
> At the target
> When migration target would populate pages for guest. As for the case
> of broken page wrt migration, we prefer keep the corresponding page,
> for the sake of seamless migration.
I don't understanding this paragraph, what do you mean by "keep the
corresponding page"? My understanding is the patch explicitly doesn't
keep the page, it marks it as broken.
Did you perhaps mean "... we prefer to keep the type of the page for the
sake..." ?
> At target it would set p2m as p2m_ram_broken for broken page. Guest MCE
> may have good chance to handle its broken page, while 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>
> Acked-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
> Acked-by: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
> Acked-by: Jan Beulich <JBeulich@xxxxxxxx>
>
> diff -r 8b93ac0c93f3 -r da7faf53790e tools/libxc/xc_domain.c
> --- a/tools/libxc/xc_domain.c Tue Nov 13 11:19:17 2012 +0000
> +++ b/tools/libxc/xc_domain.c Thu Nov 15 09:42:24 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 8b93ac0c93f3 -r da7faf53790e tools/libxc/xc_domain_restore.c
> --- a/tools/libxc/xc_domain_restore.c Tue Nov 13 11:19:17 2012 +0000
> +++ b/tools/libxc/xc_domain_restore.c Thu Nov 15 09:42:24 2012 +0800
> @@ -1023,9 +1023,15 @@
>
> 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;
> @@ -1267,6 +1273,17 @@
> /* 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 8b93ac0c93f3 -r da7faf53790e tools/libxc/xc_domain_save.c
> --- a/tools/libxc/xc_domain_save.c Tue Nov 13 11:19:17 2012 +0000
> +++ b/tools/libxc/xc_domain_save.c Thu Nov 15 09:42:24 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 8b93ac0c93f3 -r da7faf53790e tools/libxc/xenctrl.h
> --- a/tools/libxc/xenctrl.h Tue Nov 13 11:19:17 2012 +0000
> +++ b/tools/libxc/xenctrl.h Thu Nov 15 09:42:24 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 8b93ac0c93f3 -r da7faf53790e xen/arch/x86/cpu/mcheck/mcaction.c
> --- a/xen/arch/x86/cpu/mcheck/mcaction.c Tue Nov 13 11:19:17 2012 +0000
> +++ b/xen/arch/x86/cpu/mcheck/mcaction.c Thu Nov 15 09:42:24 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, broken
> + * 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 8b93ac0c93f3 -r da7faf53790e xen/arch/x86/domctl.c
> --- a/xen/arch/x86/domctl.c Tue Nov 13 11:19:17 2012 +0000
> +++ b/xen/arch/x86/domctl.c Thu Nov 15 09:42:24 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 8b93ac0c93f3 -r da7faf53790e xen/include/public/domctl.h
> --- a/xen/include/public/domctl.h Tue Nov 13 11:19:17 2012 +0000
> +++ b/xen/include/public/domctl.h Thu Nov 15 09:42:24 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_LTAB_MASK (0xfU<<28)
>
> struct xen_domctl_getpageframeinfo {
> @@ -834,6 +835,12 @@
> 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
> @@ -899,6 +906,7 @@
> #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
> @@ -954,6 +962,7 @@
> 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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