From 2eb06c306a579853346d22eda73332ed4f3e81e3 Mon Sep 17 00:00:00 2001 From: Wanpeng Li Date: Fri, 17 May 2019 16:49:49 +0800 Subject: KVM: Fix spinlock taken warning during host resume MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit WARNING: CPU: 0 PID: 13554 at kvm/arch/x86/kvm//../../../virt/kvm/kvm_main.c:4183 kvm_resume+0x3c/0x40 [kvm] CPU: 0 PID: 13554 Comm: step_after_susp Tainted: G OE 5.1.0-rc4+ #1 RIP: 0010:kvm_resume+0x3c/0x40 [kvm] Call Trace: syscore_resume+0x63/0x2d0 suspend_devices_and_enter+0x9d1/0xa40 pm_suspend+0x33a/0x3b0 state_store+0x82/0xf0 kobj_attr_store+0x12/0x20 sysfs_kf_write+0x4b/0x60 kernfs_fop_write+0x120/0x1a0 __vfs_write+0x1b/0x40 vfs_write+0xcd/0x1d0 ksys_write+0x5f/0xe0 __x64_sys_write+0x1a/0x20 do_syscall_64+0x6f/0x6c0 entry_SYSCALL_64_after_hwframe+0x49/0xbe Commit ca84d1a24 (KVM: x86: Add clock sync request to hardware enable) mentioned that "we always hold kvm_lock when hardware_enable is called. The one place that doesn't need to worry about it is resume, as resuming a frozen CPU, the spinlock won't be taken." However, commit 6706dae9 (virt/kvm: Replace spin_is_locked() with lockdep) introduces a bug, it asserts when the lock is not held which is contrary to the original goal. This patch fixes it by WARN_ON when the lock is held. Cc: Paolo Bonzini Cc: Radim Krčmář Cc: Paul E. McKenney Signed-off-by: Wanpeng Li Fixes: 6706dae9 ("virt/kvm: Replace spin_is_locked() with lockdep") [Wrap with #ifdef CONFIG_LOCKDEP - Paolo] Signed-off-by: Paolo Bonzini --- virt/kvm/kvm_main.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index f0d13d9d125d..1fadfb9cf36e 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -52,6 +52,7 @@ #include #include #include +#include #include #include @@ -4181,7 +4182,9 @@ static int kvm_suspend(void) static void kvm_resume(void) { if (kvm_usage_count) { - lockdep_assert_held(&kvm_count_lock); +#ifdef CONFIG_LOCKDEP + WARN_ON(lockdep_is_held(&kvm_count_lock)); +#endif hardware_enable_nolock(NULL); } } -- cgit v1.2.3