From: Wanpeng Li <kernellwp@gmail.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Mark Rutland <mark.rutland@arm.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: [PATCH v2] x86/kvm: Fix broken irq restoration in kvm_wait
Date: Sat, 13 Mar 2021 08:51:25 +0800 [thread overview]
Message-ID: <1615596685-22269-1-git-send-email-wanpengli@tencent.com> (raw)
From: Wanpeng Li <wanpengli@tencent.com>
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 irqflags handling in kvm_wait() which ends up doing:
local_irq_save(flags);
safe_halt();
local_irq_restore(flags);
which triggered a new consistency checking, we generally expect
local_irq_save() and local_irq_restore() to be pared and sanely
nested, and so local_irq_restore() expects to be called with
irqs disabled.
This patch fixes it by playing local_irq_disable()/enable() directly.
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
v1 -> v2:
* select the alternative fix
arch/x86/kernel/kvm.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 5e78e01..7127aef 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -836,12 +836,13 @@ static void kvm_kick_cpu(int cpu)
static void kvm_wait(u8 *ptr, u8 val)
{
- unsigned long flags;
+ bool disabled = irqs_disabled();
if (in_nmi())
return;
- local_irq_save(flags);
+ if (!disabled)
+ local_irq_disable();
if (READ_ONCE(*ptr) != val)
goto out;
@@ -851,13 +852,14 @@ static void kvm_wait(u8 *ptr, u8 val)
* 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))
+ if (disabled)
halt();
else
safe_halt();
out:
- local_irq_restore(flags);
+ if (!disabled)
+ local_irq_enable();
}
#ifdef CONFIG_X86_32
--
2.7.4
reply other threads:[~2021-03-13 0:52 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1615596685-22269-1-git-send-email-wanpengli@tencent.com \
--to=kernellwp@gmail.com \
--cc=jmattson@google.com \
--cc=joro@8bytes.org \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=pbonzini@redhat.com \
--cc=seanjc@google.com \
--cc=tglx@linutronix.de \
--cc=vkuznets@redhat.com \
--cc=wanpengli@tencent.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.