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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH V4] X86/vMCE: handle broken page with regard to migration
This patch handles broken page wrt migration. Generally there are below cases:
1. broken page occurs before migration
2. broken page occurs during migration
2.1 broken page occurs during migration but not at the last iteration
2.2 broken page occurs at the last iteration of migration
For case 1, at the sender the broken page will be mapped but not copied
to target (otherwise it may trigger more serious error, say, SRAR error).
While its pfn_type and pfn number will be transferred to target so that
target take appropriate action.
For case 2.1, at the sender mce handler marks the broken page to dirty
bitmap, so that at next iteration, its pfn_type and pfn number will be
transferred to the target and then take appropriate action.
For case 2.2, at the sender it adds a check to see if vMCE occurs at the
last iteration. If yes, it will do more iteration(s) so that the broken
page's pfn_type and pfn number will be transferred to target.
Another point is, if guest save to disk and during which vMCE occurs,
it also need do more iteration(s).
For all cases at the target (if migration not aborted by vMCE):
Target will populates pages for guest. As for the case of broken page,
we prefer to keep the type of the page for the sake of seamless migration.
Target will set p2m as p2m_ram_broken for broken page. If guest access
the broken page again it will kill itself as expected.
All above description is based on the assumption that migration will success.
However, for case 2 there are scenario that may result in guest or hypervisor
crash. When pfn_type detecting fail to get p2m_ram_broken (vMCE occur after the
detecting) and read the broken page, guest/hypervisor may survive or crash,
depending on error nature and how guest/hypervisor handle it. If
guest/hypervisor
survive, migration is OK since it will transfer pfn_type to the target at next
iter and then prevent further harm at target. If guest/hypervisor crash it
definitely needn't care migration any more. Unfortunately we have no way to
predict it, so what we can do is to do the best to handle it, after all we
cannot forbid migration for fear that it may crash guest/hypervisor.
Patch version history:
V4:
- adjust variables and patch description based on feedback
V3:
- handle pages broken at the last iteration
V2:
- migrate continue when broken page occur during migration,
via marking broken page to dirty bitmap
V1:
- migration abort when broken page occur during migration
- transfer pfn_type to target for broken page occur before migration
Suggested-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
Signed-off-by: Liu Jinsong <jinsong.liu@xxxxxxxxx>
Acked-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
- for hypervisor part of the patch
Acked-by: Jan Beulich <JBeulich@xxxxxxxx>
diff -r 8b93ac0c93f3 -r d3378692eece 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 Fri Nov 23 08:21:57 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 d3378692eece 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 Fri Nov 23 08:21:57 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 d3378692eece 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 Fri Nov 23 08:21:57 2012 +0800
@@ -1118,7 +1118,7 @@
/* Now write out each data page, canonicalising page tables as we go... */
for ( ; ; )
{
- unsigned int N, batch, run;
+ unsigned int N, batch, run, broken_before_send, broken_after_send;
char reportbuf[80];
snprintf(reportbuf, sizeof(reportbuf),
@@ -1270,6 +1270,7 @@
goto out;
}
+ broken_before_send = 0;
for ( run = j = 0; j < batch; j++ )
{
unsigned long gmfn = pfn_batch[j];
@@ -1277,6 +1278,14 @@
if ( !hvm )
gmfn = pfn_to_mfn(gmfn);
+ if ( pfn_type[j] == XEN_DOMCTL_PFINFO_BROKEN )
+ {
+ pfn_type[j] |= pfn_batch[j];
+ ++broken_before_send;
+ ++run;
+ continue;
+ }
+
if ( pfn_err[j] )
{
if ( pfn_type[j] == XEN_DOMCTL_PFINFO_XTAB )
@@ -1371,8 +1380,12 @@
}
}
- /* 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;
@@ -1484,6 +1497,38 @@
munmap(region_base, batch*PAGE_SIZE);
+ /*
+ * At the last iter, count the number of broken pages after
sending,
+ * and if there are more than before sending, do one or more iter
+ * to make sure the pages are marked broken on the receiving side.
+ */
+ if ( last_iter )
+ {
+ /* Read pfn type again */
+ for ( j = 0; j < batch; j++ )
+ {
+ if ( hvm )
+ pfn_type[j] = pfn_batch[j];
+ else
+ pfn_type[j] = pfn_to_mfn(pfn_batch[j]);
+ }
+
+ if ( xc_get_pfn_type_batch(xch, dom, batch, pfn_type) )
+ {
+ PERROR("get_pfn_type_batch failed");
+ goto out;
+ }
+
+ /* Count the number of broken pages */
+ broken_after_send = 0;
+ for ( j = 0; j < batch; j++ )
+ if ( pfn_type[j] == XEN_DOMCTL_PFINFO_BROKEN )
+ broken_after_send++;
+
+ /* If there are more than before sending, do more iter(s) */
+ if ( broken_before_send < broken_after_send )
+ last_iter = 0;
+ }
} /* end of this while loop for this iteration */
skip:
@@ -1550,23 +1595,22 @@
PERROR("Error when writing to state file (tsc)");
goto out;
}
+ }
+ }
+ else
+ last_iter = 1;
+ if ( xc_shadow_control(xch, dom,
+ XEN_DOMCTL_SHADOW_OP_CLEAN,
HYPERCALL_BUFFER(to_send),
+ dinfo->p2m_size, NULL, 0, &shadow_stats) !=
dinfo->p2m_size )
+ {
+ PERROR("Error flushing shadow PT");
+ goto out;
+ }
- }
+ sent_last_iter = sent_this_iter;
- if ( xc_shadow_control(xch, dom,
- XEN_DOMCTL_SHADOW_OP_CLEAN,
HYPERCALL_BUFFER(to_send),
- dinfo->p2m_size, NULL, 0, &shadow_stats) !=
dinfo->p2m_size )
- {
- PERROR("Error flushing shadow PT");
- goto out;
- }
-
- sent_last_iter = sent_this_iter;
-
- print_stats(xch, dom, sent_this_iter, &time_stats, &shadow_stats,
1);
-
- }
+ print_stats(xch, dom, sent_this_iter, &time_stats, &shadow_stats, 1);
} /* end of infinite for loop */
DPRINTF("All memory is saved\n");
diff -r 8b93ac0c93f3 -r d3378692eece tools/libxc/xenctrl.h
--- a/tools/libxc/xenctrl.h Tue Nov 13 11:19:17 2012 +0000
+++ b/tools/libxc/xenctrl.h Fri Nov 23 08:21:57 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 d3378692eece 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 Fri Nov 23 08:21:57 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 d3378692eece 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 Fri Nov 23 08:21:57 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 d3378692eece 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 Fri Nov 23 08:21:57 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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