On 4/28/2017 3:45 PM, Zhang, Xiong Y wrote:
I found this patch couldn't work, the reason is inline. And need propose to
fix this.
diff --git a/xen/arch/x86/hvm/dm.c b/xen/arch/x86/hvm/dm.c
index 7e0da81..d72b7bd 100644
--- a/xen/arch/x86/hvm/dm.c
+++ b/xen/arch/x86/hvm/dm.c
@@ -384,15 +384,50 @@ static int dm_op(domid_t domid,
case XEN_DMOP_map_mem_type_to_ioreq_server:
{
- const struct xen_dm_op_map_mem_type_to_ioreq_server *data =
+ struct xen_dm_op_map_mem_type_to_ioreq_server *data =
&op.u.map_mem_type_to_ioreq_server;
+ unsigned long first_gfn = data->opaque;
+
+ const_op = false;
rc = -EOPNOTSUPP;
if ( !hap_enabled(d) )
break;
- rc = hvm_map_mem_type_to_ioreq_server(d, data->id,
- data->type, data->flags);
+ if ( first_gfn == 0 )
+ rc = hvm_map_mem_type_to_ioreq_server(d, data->id,
+ data->type,
data->flags);
+ else
+ rc = 0;
+
+ /*
+ * Iterate p2m table when an ioreq server unmaps from
p2m_ioreq_server,
+ * and reset the remaining p2m_ioreq_server entries back to
p2m_ram_rw.
+ */
+ if ( rc == 0 && data->flags == 0 )
+ {
+ struct p2m_domain *p2m = p2m_get_hostp2m(d);
+
+ while ( read_atomic(&p2m->ioreq.entry_count) &&
+ first_gfn <= p2m->max_mapped_pfn )
+ {
+ /* Iterate p2m table for 256 gfns each time. */
+ p2m_finish_type_change(d, _gfn(first_gfn), 256,
+ p2m_ioreq_server,
p2m_ram_rw);
+
+ first_gfn += 256;
+
+ /* Check for continuation if it's not the last iteration. */
+ if ( first_gfn <= p2m->max_mapped_pfn &&
+ hypercall_preempt_check() )
+ {
+ rc = -ERESTART;
+ data->opaque = first_gfn;
+ break;
+ }
+ }
+ }
+
break;
}
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 4169d18..1d57e5c 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -1011,6 +1011,35 @@ void p2m_change_type_range(struct domain *d,
p2m_unlock(p2m);
}
+/* Synchronously modify the p2m type for a range of gfns from ot to nt. */
+void p2m_finish_type_change(struct domain *d,
+ gfn_t first_gfn, unsigned long max_nr,
+ p2m_type_t ot, p2m_type_t nt)
+{
+ struct p2m_domain *p2m = p2m_get_hostp2m(d);
+ p2m_type_t t;
+ unsigned long gfn = gfn_x(first_gfn);
+ unsigned long last_gfn = gfn + max_nr - 1;
+
+ ASSERT(ot != nt);
+ ASSERT(p2m_is_changeable(ot) && p2m_is_changeable(nt));
+
+ p2m_lock(p2m);
+
+ last_gfn = min(last_gfn, p2m->max_mapped_pfn);
+ while ( gfn <= last_gfn )
+ {
+ get_gfn_query_unlocked(d, gfn, &t);
[Zhang, Xiong Y] As the previous patch "asynchronously reset outstanding
p2m_ioreq_server_entries" call ept_chang_entry_type_global() which
set ept_entry.recalc=1 and ept_entry.emt=MTRR_NUM_TYPES. So
get_gfn_query_unlocked(gfn) will recalc gfn mem_type and return
the new mem_type not the old mem_type.
For pfn is old p2m_ioreq_server mem_type, the returned &t is p2m_raw_rw.
Then (t == ot) couldn't be true, and p2m_change_type_one() never be called.
This result a guest vm using this interface couldn't reboot.
The root cause is in the last version of patch 5/6, that p2m_ram_rw is
returned for ioreq server pages whenever there's no mapping ioreq server.
There's no such problem for version 12 and earlier ones.
I have sent Xiong a patch to fix this. Maybe he can send out the fix
patch after XenGT tests pass.
BTW, thanks Xiong for helping find this error. :)
Thanks
Yu
[snip]
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