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| author | Wanpeng Li <wanpengli@tencent.com> | 2021-03-15 14:55:28 +0800 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-03-18 13:58:14 -0400 |
| commit | f4e61f0c9add3b00bd5f2df3c814d688849b8707 (patch) | |
| tree | 288941d008a8996551da972d7db2bcf283961e78 | |
| parent | c2162e13d6e2f43e5001a356196871642de070ba (diff) | |
| download | linux-f4e61f0c9add3b00bd5f2df3c814d688849b8707.tar.gz linux-f4e61f0c9add3b00bd5f2df3c814d688849b8707.tar.bz2 linux-f4e61f0c9add3b00bd5f2df3c814d688849b8707.zip | |
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>
| -rw-r--r-- | arch/x86/kernel/kvm.c | 23 |
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 |