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xen-ia64-devel
Re: [Xen-ia64-devel] Patch for PV-on-HVM for IPF
Sorry, I forgot to attach the patch.
DOI Tsunehisa wrote:
> Hi all,
>
> Currently, we are testing PV-on-HVM driver for IPF. so, we found
> a problem that hypervisor crashes during VT-i domain destruction
> with PV-on-HVM driver.
>
> The procedure to reproduce this problem are:
>
> * Create a VT-i domain.
> [dom0]# xm create -f hvm.conf
> * Insert modules for PV-on-HVM on the domain.
> [domvti]# insmod xen-platform-pci.ko
> [domvti]# insmod xenbus.ko
> [domvti]# insmod xen-vbd.ko
> [domvti]# insmod xen-vnif.ko
> * Activate VNIF network interface.
> [dom0]# xm network-attach <domid> eth1
> [domvti]# ifconfig eth1 up
> * Destruct the domain
> [dom0]# xm destroy <domid>
> ..... hypervisor crash ....
>
> We were investigating the hypervisor crash mechanism, thus we found
> a reason of it.
>
> * VNIF of PV-on-HVM uses gnttab_copy() function.
> - it's used for copy-method of VNIF backend.
> - it needs to refer p2m table.
> * gnttab_copy() function may be called during the domain destruction.
> - it's called by dom0 VNIF backend.
> * Hypervisor invalidates p2m table at first during the destruction.
> - gnttab_copy() won't be able to refer p2m table, thus it occurs
> hypervisor crash.
> - In x86 code, p2m table invalidation is delayed at last phase of
> domain destruction.
> => but we don't like it. it seems that p2m table exists after
> memory relinquised.
>
> So, I'll post a patch to avoid hypervisor crash.
>
> * pv-avoid-crash.patch
> + modify p2m table converter (gmfn_to_mfn_foreign())
> - return INVALID_MFN during VT-i domain destruction
>
> We tested that the problem is solved.
>
> Thanks,
> - Tsunehisa Doi
>
>
> _______________________________________________
> Xen-ia64-devel mailing list
> Xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-ia64-devel
# HG changeset patch
# User Doi.Tsunehisa@xxxxxxxxxxxxxx
# Node ID 354f40902eb9e3f92fdf8b5e9268052cd955230b
# Parent f34e37d0742d80ccfefd017a91f93310ebc2dfe8
Modify p2m converter to avoid hypervisor crash
during destruction of VT-i domain with PV-on-HVM.
Signed-off-by: Tsunehisa Doi <Doi.Tsunehisa@xxxxxxxxxxxxxx>
Signed-off-by: Tomonari Horikoshi <t.horikoshi@xxxxxxxxxxxxxx>
diff -r f34e37d0742d -r 354f40902eb9 xen/arch/ia64/xen/mm.c
--- a/xen/arch/ia64/xen/mm.c Tue Sep 26 19:11:33 2006 -0600
+++ b/xen/arch/ia64/xen/mm.c Wed Sep 27 17:24:58 2006 +0900
@@ -396,6 +396,12 @@ gmfn_to_mfn_foreign(struct domain *d, un
{
unsigned long pte;
+ // This function may be called from __gnttab_copy()
+ // during destruction of VT-i domain with PV-on-HVM driver.
+ if (unlikely(d->arch.mm.pgd == NULL)) {
+ if (VMX_DOMAIN(d->vcpu[0]))
+ return INVALID_MFN;
+ }
pte = lookup_domain_mpa(d,gpfn << PAGE_SHIFT, NULL);
if (!pte) {
panic("gmfn_to_mfn_foreign: bad gpfn. spinning...\n");
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