On 3/21/2017 6:00 PM, Paul Durrant wrote:
-----Original Message-----
From: Yu Zhang [mailto:yu.c.zh...@linux.intel.com]
Sent: 21 March 2017 02:53
To: xen-devel@lists.xen.org
Cc: zhiyuan...@intel.com; Paul Durrant <paul.durr...@citrix.com>; Jan
Beulich <jbeul...@suse.com>; Andrew Cooper
<andrew.coop...@citrix.com>; George Dunlap
<george.dun...@citrix.com>
Subject: [PATCH v9 5/5] x86/ioreq server: Synchronously reset outstanding
p2m_ioreq_server entries when an ioreq server unmaps.
After an ioreq server has unmapped, the remaining p2m_ioreq_server
entries need to be reset back to p2m_ram_rw. This patch does this
synchronously by iterating the p2m table.
The synchronous resetting is necessary because we need to guarantee
the p2m table is clean before another ioreq server is mapped. And
since the sweeping of p2m table could be time consuming, it is done
with hypercall continuation.
Signed-off-by: Yu Zhang <yu.c.zh...@linux.intel.com>
---
Cc: Paul Durrant <paul.durr...@citrix.com>
Cc: Jan Beulich <jbeul...@suse.com>
Cc: Andrew Cooper <andrew.coop...@citrix.com>
Cc: George Dunlap <george.dun...@eu.citrix.com>
changes in v2:
- According to comments from Jan and Andrew: do not use the
HVMOP type hypercall continuation method. Instead, adding
an opaque in xen_dm_op_map_mem_type_to_ioreq_server to
store the gfn.
- According to comments from Jan: change routine's comments
and name of parameters of p2m_finish_type_change().
changes in v1:
- This patch is splitted from patch 4 of last version.
- According to comments from Jan: update the gfn_start for
when use hypercall continuation to reset the p2m type.
- According to comments from Jan: use min() to compare gfn_end
and max mapped pfn in p2m_finish_type_change()
---
xen/arch/x86/hvm/dm.c | 41
++++++++++++++++++++++++++++++++++++++---
xen/arch/x86/mm/p2m.c | 29 +++++++++++++++++++++++++++++
xen/include/asm-x86/p2m.h | 7 +++++++
3 files changed, 74 insertions(+), 3 deletions(-)
diff --git a/xen/arch/x86/hvm/dm.c b/xen/arch/x86/hvm/dm.c
index 3f9484d..a24d0f8 100644
--- a/xen/arch/x86/hvm/dm.c
+++ b/xen/arch/x86/hvm/dm.c
@@ -385,16 +385,51 @@ 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;
+ unsigned long last_gfn;
+
+ const_op = false;
rc = -EOPNOTSUPP;
/* Only support for HAP enabled hvm. */
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);
+ /*
+ * 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 ( (first_gfn > 0) || (data->flags == 0 && rc == 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. */
+ last_gfn = first_gfn + 0xff;
+
Might be worth a comment here to sat that p2m_finish_type_change() limits
last_gfn appropriately because it kind of looks wrong to be blindly calling it
with first_gfn + 0xff. Or perhaps, rather than passing last_gfn, pass a
'max_nr' parameter of 256 instead. Then you can drop last_gfn altogether. If
you prefer the parameters as they are then at least limit the scope of last_gfn
to this while loop.
Thanks for your comments, Paul. :)
Well, setting last_gfn with first_gfn+0xff looks a bit awkward. But why
using a 'max_nr' with a magic number, say 256, looks better? Or any
other benefits? :-)
Yu
+ p2m_finish_type_change(d, first_gfn, last_gfn,
+ p2m_ioreq_server, p2m_ram_rw);
+
+ first_gfn = last_gfn + 1;
+
+ /* 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 e3e54f1..0a2f276 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -1038,6 +1038,35 @@ 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,
As I said above, consider a 'max_nr' parameter here rather than last_gfn.
Paul
+ unsigned long first_gfn, unsigned long last_gfn,
+ p2m_type_t ot, p2m_type_t nt)
+{
+ struct p2m_domain *p2m = p2m_get_hostp2m(d);
+ p2m_type_t t;
+ unsigned long gfn = first_gfn;
+
+ ASSERT(first_gfn <= last_gfn);
+ 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);
+
+ if ( t == ot )
+ p2m_change_type_one(d, gfn, t, nt);
+
+ gfn++;
+ }
+
+ p2m_unlock(p2m);
+}
+
/*
* Returns:
* 0 for success
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index 395f125..3d665e8 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -611,6 +611,13 @@ void p2m_change_type_range(struct domain *d,
int p2m_change_type_one(struct domain *d, unsigned long gfn,
p2m_type_t ot, p2m_type_t nt);
+/* Synchronously change the p2m type for a range of gfns:
+ * [first_gfn ... last_gfn]. */
+void p2m_finish_type_change(struct domain *d,
+ unsigned long first_gfn,
+ unsigned long last_gfn,
+ p2m_type_t ot, p2m_type_t nt);
+
/* Report a change affecting memory types. */
void p2m_memory_type_changed(struct domain *d);
--
1.9.1
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