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authorWanpeng Li <wanpengli@tencent.com>2021-03-15 09:55:28 +0300
committerPaolo Bonzini <pbonzini@redhat.com>2021-03-18 20:58:14 +0300
commitf4e61f0c9add3b00bd5f2df3c814d688849b8707 (patch)
tree288941d008a8996551da972d7db2bcf283961e78 /arch
parentc2162e13d6e2f43e5001a356196871642de070ba (diff)
downloadlinux-f4e61f0c9add3b00bd5f2df3c814d688849b8707.tar.xz
x86/kvm: Fix broken irq restoration in kvm_wait
After commit 997acaf6b4b59c (lockdep: report broken irq restoration), the guest splatting below during boot: raw_local_irq_restore() called with IRQs enabled WARNING: CPU: 1 PID: 169 at kernel/locking/irqflag-debug.c:10 warn_bogus_irq_restore+0x26/0x30 Modules linked in: hid_generic usbhid hid CPU: 1 PID: 169 Comm: systemd-udevd Not tainted 5.11.0+ #25 RIP: 0010:warn_bogus_irq_restore+0x26/0x30 Call Trace: kvm_wait+0x76/0x90 __pv_queued_spin_lock_slowpath+0x285/0x2e0 do_raw_spin_lock+0xc9/0xd0 _raw_spin_lock+0x59/0x70 lockref_get_not_dead+0xf/0x50 __legitimize_path+0x31/0x60 legitimize_root+0x37/0x50 try_to_unlazy_next+0x7f/0x1d0 lookup_fast+0xb0/0x170 path_openat+0x165/0x9b0 do_filp_open+0x99/0x110 do_sys_openat2+0x1f1/0x2e0 do_sys_open+0x5c/0x80 __x64_sys_open+0x21/0x30 do_syscall_64+0x32/0x50 entry_SYSCALL_64_after_hwframe+0x44/0xae The new consistency checking, expects local_irq_save() and local_irq_restore() to be paired and sanely nested, and therefore expects local_irq_restore() to be called with irqs disabled. The irqflags handling in kvm_wait() which ends up doing: local_irq_save(flags); safe_halt(); local_irq_restore(flags); instead triggers it. This patch fixes it by using local_irq_disable()/enable() directly. Cc: Thomas Gleixner <tglx@linutronix.de> Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Wanpeng Li <wanpengli@tencent.com> Message-Id: <1615791328-2735-1-git-send-email-wanpengli@tencent.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/kvm.c23
1 files changed, 10 insertions, 13 deletions
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 5e78e01ca3b4..78bb0fae3982 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -836,28 +836,25 @@ static void kvm_kick_cpu(int cpu)
static void kvm_wait(u8 *ptr, u8 val)
{
- unsigned long flags;
-
if (in_nmi())
return;
- local_irq_save(flags);
-
- if (READ_ONCE(*ptr) != val)
- goto out;
-
/*
* halt until it's our turn and kicked. Note that we do safe halt
* for irq enabled case to avoid hang when lock info is overwritten
* in irq spinlock slowpath and no spurious interrupt occur to save us.
*/
- if (arch_irqs_disabled_flags(flags))
- halt();
- else
- safe_halt();
+ if (irqs_disabled()) {
+ if (READ_ONCE(*ptr) == val)
+ halt();
+ } else {
+ local_irq_disable();
-out:
- local_irq_restore(flags);
+ if (READ_ONCE(*ptr) == val)
+ safe_halt();
+
+ local_irq_enable();
+ }
}
#ifdef CONFIG_X86_32