[Xen-devel] [PATCH v2] x86/hvm: do not register hpet mmio during s3 cycle

[Eric Chanudet <chanudete@xxxxxxxxxxxx>]

Do it once at domain creation (hpet_init).

Sleep -> Resume cycles will end up crashing an HVM guest with hpet as
the sequence during resume takes the path:
-> hvm_s3_suspend
  -> hpet_reset
    -> hpet_deinit
    -> hpet_init
      -> register_mmio_handler
        -> hvm_next_io_handler

register_mmio_handler will use a new io handler each time, until
eventually it reaches NR_IO_HANDLERS, then hvm_next_io_handler calls
domain_crash.

Signed-off-by: Eric Chanudet <chanudete@xxxxxxxxxxxx>

---
v2:
  * make hpet_reinit static inline (one call site in this file)
  * remove single use local variable.
---
 xen/arch/x86/hvm/hpet.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/xen/arch/x86/hvm/hpet.c b/xen/arch/x86/hvm/hpet.c
index 3ea895a0fb..d8c61ca155 100644
--- a/xen/arch/x86/hvm/hpet.c
+++ b/xen/arch/x86/hvm/hpet.c
@@ -635,14 +635,10 @@ static int hpet_load(struct domain *d, 
hvm_domain_context_t *h)
 
 HVM_REGISTER_SAVE_RESTORE(HPET, hpet_save, hpet_load, 1, HVMSR_PER_DOM);
 
-void hpet_init(struct domain *d)
+static void hpet_set(HPETState *h)
 {
-    HPETState *h = domain_vhpet(d);
     int i;
 
-    if ( !has_vhpet(d) )
-        return;
-
     memset(h, 0, sizeof(HPETState));
 
     rwlock_init(&h->lock);
@@ -668,11 +664,26 @@ void hpet_init(struct domain *d)
         h->hpet.comparator64[i] = ~0ULL;
         h->pt[i].source = PTSRC_isa;
     }
+}
 
+void hpet_init(struct domain *d)
+{
+    if ( !has_vhpet(d) )
+        return;
+
+    hpet_set(domain_vhpet(d));
     register_mmio_handler(d, &hpet_mmio_ops);
     d->arch.hvm_domain.params[HVM_PARAM_HPET_ENABLED] = 1;
 }
 
+static inline void hpet_reinit(struct domain *d)
+{
+    if ( !has_vhpet(d) )
+        return;
+
+    hpet_set(domain_vhpet(d));
+}
+
 void hpet_deinit(struct domain *d)
 {
     int i;
@@ -698,7 +709,7 @@ void hpet_deinit(struct domain *d)
 void hpet_reset(struct domain *d)
 {
     hpet_deinit(d);
-    hpet_init(d);
+    hpet_reinit(d);
 }
 
 /*
-- 
2.14.2

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