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From: Henry Wang <Henry.Wang@arm.com>
To: xen-devel@lists.xenproject.org
Cc: Henry Wang <Henry.Wang@arm.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Julien Grall <julien@xen.org>,
	Bertrand Marquis <bertrand.marquis@arm.com>,
	Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	George Dunlap <george.dunlap@citrix.com>,
	Jan Beulich <jbeulich@suse.com>, Wei Liu <wl@xen.org>,
	Wei Chen <wei.chen@arm.com>, Henry Wang <henry.wang@arm.com>,
	Wei Chen <Wei.Chen@arm.com>, Julien Grall <jgrall@amazon.com>
Subject: [PATCH v2 1/2] xen/arm: Defer request_irq on secondary CPUs after local_irq_enable
Date: Fri,  6 May 2022 13:52:00 +0800	[thread overview]
Message-ID: <20220506055201.999277-2-Henry.Wang@arm.com> (raw)
In-Reply-To: <20220506055201.999277-1-Henry.Wang@arm.com>

With the enhanced ASSERT_ALLOC_CONTEXT, calling request_irq before
local_irq_enable on secondary cores will lead to

(XEN) Xen call trace:
(XEN) [<000000000021d86c>] alloc_xenheap_pages+0x74/0x194 (PC)
(XEN) [<000000000021d864>] alloc_xenheap_pages+0x6c/0x194 (LR)
(XEN) [<0000000000229e90>] xmalloc_tlsf.c#xmalloc_pool_get+0x1c/0x28
(XEN) [<000000000022a270>] xmem_pool_alloc+0x21c/0x448
(XEN) [<000000000022a8dc>] _xmalloc+0x8c/0x290
(XEN) [<000000000026b57c>] request_irq+0x40/0xb8
(XEN) [<0000000000272780>] init_timer_interrupt+0x74/0xcc
(XEN) [<000000000027212c>] start_secondary+0x1b4/0x238
(XEN) [<0000000084000200>] 0000000084000200
(XEN)
(XEN)
(XEN) ****************************************
(XEN) Panic on CPU 4:
(XEN) Assertion '!in_irq() && (local_irq_is_enabled() ||
num_online_cpus() <= 1)' failed at common/page_alloc.c:2212
(XEN) ****************************************

on systems without a big enough pool for xmalloc() to cater the
requested size.

Moving the call of request_irq() past local_irq_enable() on
secondary cores will make sure the assertion condition in
alloc_xenheap_pages(), i.e. !in_irq && local_irq_enabled() is
satisfied. It is also safe because the timer and GIC maintenance
interrupt will not be used until the CPU is fully online.

Reported-by: Wei Chen <Wei.Chen@arm.com>
Suggested-by: Julien Grall <jgrall@amazon.com>
Signed-off-by: Henry Wang <Henry.Wang@arm.com>
---
v1 -> v2:
- Explain why the moving of code is safe in the commit message and
add comments.
---
 xen/arch/arm/smpboot.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/xen/arch/arm/smpboot.c b/xen/arch/arm/smpboot.c
index 7bfd0a73a7..9bb32a301a 100644
--- a/xen/arch/arm/smpboot.c
+++ b/xen/arch/arm/smpboot.c
@@ -361,9 +361,6 @@ void start_secondary(void)
 
     init_secondary_IRQ();
 
-    init_maintenance_interrupt();
-    init_timer_interrupt();
-
     set_current(idle_vcpu[cpuid]);
 
     setup_cpu_sibling_map(cpuid);
@@ -380,6 +377,15 @@ void start_secondary(void)
     cpumask_set_cpu(cpuid, &cpu_online_map);
 
     local_irq_enable();
+
+    /*
+     * Calling request_irq() after local_irq_enable() on secondary cores
+     * will make sure the assertion condition in alloc_xenheap_pages(),
+     * i.e. !in_irq && local_irq_enabled() is satisfied.
+     */
+    init_maintenance_interrupt();
+    init_timer_interrupt();
+
     local_abort_enable();
 
     check_local_cpu_errata();
-- 
2.25.1



  reply	other threads:[~2022-05-06  5:52 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-06  5:51 [PATCH v2 0/2] Adjustment after introducing ASSERT_ALLOC_CONTEXT Henry Wang
2022-05-06  5:52 ` Henry Wang [this message]
2022-05-06  5:52 ` [PATCH v2 2/2] xen/common: Use enhanced ASSERT_ALLOC_CONTEXT in xmalloc() Henry Wang
2022-05-06 10:32   ` Jan Beulich
2022-05-06 12:03     ` Henry Wang
2022-05-06 12:27       ` Jan Beulich
2022-05-06 12:39         ` Henry Wang

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