[Xen-devel] [PATCH v3 13/17] livepatch: Expand spin_debug_disable in [apply|revert]_payload

[Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx>]

Under ARM64 the vmap calls were all done with IRQs disabled which
didn't trip the spinlock debug check (as seen on x86):

livepatch.c:1330: livepatch: xen_hello_world: timeout is 30000000ns
livepatch.c:1437: livepatch: xen_hello_world: CPU3 - IPIing the other 3 CPUs
Applying xen_hello_world... (XEN) livepatch: xen_hello_world: Applying 1 
functions
Xen BUG at spinlock.c:47
..snip..
    [<ffff82d0802379b1>] spinlock.c#check_lock+0x3e/0x44
    [<ffff82d080237a70>] _spin_lock+0x11/0x4a
    [<ffff82d08023e2de>] __vmap+0x78/0x381
    [<ffff82d080219c13>] livepatch.c#livepatch_quiesce+0xc4/0x1bf
    [<ffff82d080219ee3>] livepatch.c#apply_payload+0x3a/0x102
    [<ffff82d08021a19e>] check_for_livepatch_work+0x1f3/0x390
    [<ffff82d08027b7f4>] domain.c#continue_idle_domain+0x1b/0x22

But are definitly the case on x86 - so we expand the scope
of the spin_debug_disable.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
 xen/common/livepatch.c | 30 ++++++++++++++++--------------
 1 file changed, 16 insertions(+), 14 deletions(-)

diff --git a/xen/common/livepatch.c b/xen/common/livepatch.c
index 93083cda1a..2f5ee1ae75 100644
--- a/xen/common/livepatch.c
+++ b/xen/common/livepatch.c
@@ -1154,22 +1154,22 @@ static int apply_payload(struct payload *data)
     printk(XENLOG_INFO LIVEPATCH "%s: Applying %u functions\n",
             data->name, data->nfuncs);
 
+    /*
+     * Since we are running with IRQs disabled and the hooks may call common
+     * code - which expects certain spinlocks to run with IRQs enabled - we
+     * temporarily disable the spin locks IRQ state checks.
+     */
+    spin_debug_disable();
     rc = livepatch_quiesce(data->funcs, data->nfuncs);
     if ( rc )
     {
+        spin_debug_enable();
         printk(XENLOG_ERR LIVEPATCH "%s: unable to quiesce!\n", data->name);
         return rc;
     }
 
-    /*
-     * Since we are running with IRQs disabled and the hooks may call common
-     * code - which expects certain spinlocks to run with IRQs enabled - we
-     * temporarily disable the spin locks IRQ state checks.
-     */
-    spin_debug_disable();
     for ( i = 0; i < data->n_load_funcs; i++ )
         data->load_funcs[i]();
-    spin_debug_enable();
 
     ASSERT(!local_irq_is_enabled());
 
@@ -1177,6 +1177,7 @@ static int apply_payload(struct payload *data)
         arch_livepatch_apply(&data->funcs[i]);
 
     livepatch_revive();
+    spin_debug_enable();
 
     /*
      * We need RCU variant (which has barriers) in case we crash here.
@@ -1195,9 +1196,16 @@ static int revert_payload(struct payload *data)
 
     printk(XENLOG_INFO LIVEPATCH "%s: Reverting\n", data->name);
 
+    /*
+     * Since we are running with IRQs disabled and the hooks may call common
+     * code - which expects certain spinlocks to run with IRQs enabled - we
+     * temporarily disable the spin locks IRQ state checks.
+     */
+    spin_debug_disable();
     rc = livepatch_quiesce(data->funcs, data->nfuncs);
     if ( rc )
     {
+        spin_debug_enable();
         printk(XENLOG_ERR LIVEPATCH "%s: unable to quiesce!\n", data->name);
         return rc;
     }
@@ -1205,19 +1213,13 @@ static int revert_payload(struct payload *data)
     for ( i = 0; i < data->nfuncs; i++ )
         livepatch_revert(&data->funcs[i]);
 
-    /*
-     * Since we are running with IRQs disabled and the hooks may call common
-     * code - which expects certain spinlocks to run with IRQs enabled - we
-     * temporarily disable the spin locks IRQ state checks.
-     */
-    spin_debug_disable();
     for ( i = 0; i < data->n_unload_funcs; i++ )
         data->unload_funcs[i]();
-    spin_debug_enable();
 
     ASSERT(!local_irq_is_enabled());
 
     livepatch_revive();
+    spin_debug_enable();
 
     /*
      * We need RCU variant (which has barriers) in case we crash here.
-- 
2.13.3


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