Hi Yamahata-san,
Thank you for your comment.
You (yamahata) said:
> On Tue, Mar 06, 2007 at 09:56:14PM +0900, DOI Tsunehisa wrote:
>> - we have to modify guest_physmap_add_page() to support it.
>> (this is straight reason of hypervisor crash)
>
> The patch breaks the the p2m/m2p table convension.
> get_page() shouldn't fail because xen heap page must be owned
> by the domain when guest_physmap_add_page() is called.
> share_xen_page_with_guest() does it.
I've thought that this patch is tricky, but I didn't find the
correct way to modify to avoid hypervisor crash issue.
> What kind of page was passed when you observed the panic?
> Who allocated and passed it?
Currently, without this patch, hypervisor crashes in PV-on-HVM
initialization phase..
* at share_info page remapping: success
- called from HYPERVISOR_memory_op in init_xen_info()..
(unmodified_drivers/linux-2.6/platform-pci/platform-pci.c)
* at grant table page remapping: crash
- called from gnttab_init() in init_xen_info()
- call tree in driver code is
gnttab_init() -> gnttab_resume() -> gnttab_map()
-> HYPERVISOR_memory_op
(linux-2.6-xen-sparse/drivers/xen/core/gnttab.c)
- at guest_physmap_add_page() in hypervisor code,
1706 void
1707 guest_physmap_add_page(struct domain *d, unsigned long gpfn,
1708 unsigned long mfn)
1709 {
1710 int ret;
1711
1712 BUG_ON(!mfn_valid(mfn));
1713 ret = get_page(mfn_to_page(mfn), d);
1714 BUG_ON(ret == 0); <<==== it crashes at this point.
1715 set_gpfn_from_mfn(mfn, gpfn);
1716 smp_mb();
So, at grant table page remapping, the hypervisor crashes,
I think.
Thanks,
- Tsunehisa Doi
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