[PATCH] xen: Remove domain_crash_synchronous() completely

* [PATCH] xen: Remove domain_crash_synchronous() completely
@ 2018-08-01 13:29 Andrew Cooper
  2018-08-01 13:40 ` Jan Beulich
  2018-08-01 13:50 ` Roger Pau Monné
  0 siblings, 2 replies; 5+ messages in thread
From: Andrew Cooper @ 2018-08-01 13:29 UTC (permalink / raw)
  To: Xen-devel
  Cc: Stefano Stabellini, Wei Liu, Andrew Cooper, Julien Grall,
	Jan Beulich, Roger Pau Monné

domain_crash_synchronous() is unsafe to use in general as it may leave
spinlocks held, temporary memory allocated, etc.

With domain_crash_synchronous() removed from the ARM code in 4.11, take the
opportunity to remove the infrastructure completely by opencoding the softirq
loop in the remaining callsites, all of which are destined for deletion.

None of these sites are at risk of having a pending ioreq to qemu, which means
that the vcpu_end_shutdown_deferral() isn't necessary.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Stefano Stabellini <sstabellini@kernel.org>
CC: Julien Grall <julien.grall@arm.com>
CC: Wei Liu <wei.liu2@citrix.com>
CC: Roger Pau Monné <roger.pau@citrix.com>

asm_domain_crash_synchronous() will be removed by my "lift exception frame
logic up into C" series, while the waitqueue callers will be removed when the
vm_event ring mapping infrastructure is complete.
---
 xen/arch/x86/traps.c    |  5 ++++-
 xen/common/domain.c     | 11 -----------
 xen/common/wait.c       | 13 ++++++++++---
 xen/include/xen/sched.h | 10 ----------
 4 files changed, 14 insertions(+), 25 deletions(-)

diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 789d7ff..ddff346 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -2215,7 +2215,10 @@ void asm_domain_crash_synchronous(unsigned long addr)
     printk("domain_crash_sync called from entry.S: fault at %p %pS\n",
            _p(addr), _p(addr));
 
-    __domain_crash_synchronous();
+    __domain_crash(current->domain);
+
+    for ( ; ; )
+        do_softirq();
 }
 
 /*
diff --git a/xen/common/domain.c b/xen/common/domain.c
index 08ca4b1..749722b 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -700,17 +700,6 @@ void __domain_crash(struct domain *d)
 }
 
 
-void __domain_crash_synchronous(void)
-{
-    __domain_crash(current->domain);
-
-    vcpu_end_shutdown_deferral(current);
-
-    for ( ; ; )
-        do_softirq();
-}
-
-
 int domain_shutdown(struct domain *d, u8 reason)
 {
     struct vcpu *v;
diff --git a/xen/common/wait.c b/xen/common/wait.c
index a57bc10..4f830a1 100644
--- a/xen/common/wait.c
+++ b/xen/common/wait.c
@@ -20,6 +20,7 @@
  */
 
 #include <xen/sched.h>
+#include <xen/softirq.h>
 #include <xen/wait.h>
 #include <xen/errno.h>
 
@@ -135,7 +136,10 @@ static void __prepare_to_wait(struct waitqueue_vcpu *wqv)
     if ( vcpu_set_hard_affinity(curr, cpumask_of(wqv->wakeup_cpu)) )
     {
         gdprintk(XENLOG_ERR, "Unable to set vcpu affinity\n");
-        domain_crash_synchronous();
+        domain_crash(current->domain);
+
+        for ( ; ; )
+            do_softirq();
     }
 
     /* Hand-rolled setjmp(). */
@@ -166,7 +170,10 @@ static void __prepare_to_wait(struct waitqueue_vcpu *wqv)
     if ( unlikely(wqv->esp == 0) )
     {
         gdprintk(XENLOG_ERR, "Stack too large in %s\n", __func__);
-        domain_crash_synchronous();
+        domain_crash(current->domain);
+
+        for ( ; ; )
+            do_softirq();
     }
 
     cpu_info->guest_cpu_user_regs.entry_vector = entry_vector;
@@ -196,7 +203,7 @@ void check_wakeup_from_wait(void)
         if ( vcpu_set_hard_affinity(curr, cpumask_of(wqv->wakeup_cpu)) )
         {
             gdprintk(XENLOG_ERR, "Unable to set vcpu affinity\n");
-            domain_crash_synchronous();
+            domain_crash(current->domain);
         }
         wait(); /* takes us back into the scheduler */
     }
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 851f11e..3c35473 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -617,16 +617,6 @@ void __domain_crash(struct domain *d);
 } while (0)
 
 /*
- * Mark current domain as crashed and synchronously deschedule from the local
- * processor. This function never returns.
- */
-void noreturn __domain_crash_synchronous(void);
-#define domain_crash_synchronous() do {                                   \
-    printk("domain_crash_sync called from %s:%d\n", __FILE__, __LINE__);  \
-    __domain_crash_synchronous();                                         \
-} while (0)
-
-/*
  * Called from assembly code, with an optional address to help indicate why
  * the crash occured.  If addr is 0, look up address from last extable
  * redirection.
-- 
2.1.4


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