linux/arch
David Woodhouse 8228c77d8b KVM: x86: switch pvclock_gtod_sync_lock to a raw spinlock
On the preemption path when updating a Xen guest's runstate times, this
lock is taken inside the scheduler rq->lock, which is a raw spinlock.
This was shown in a lockdep warning:

[   89.138354] =============================
[   89.138356] [ BUG: Invalid wait context ]
[   89.138358] 5.15.0-rc5+ #834 Tainted: G S        I E
[   89.138360] -----------------------------
[   89.138361] xen_shinfo_test/2575 is trying to lock:
[   89.138363] ffffa34a0364efd8 (&kvm->arch.pvclock_gtod_sync_lock){....}-{3:3}, at: get_kvmclock_ns+0x1f/0x130 [kvm]
[   89.138442] other info that might help us debug this:
[   89.138444] context-{5:5}
[   89.138445] 4 locks held by xen_shinfo_test/2575:
[   89.138447]  #0: ffff972bdc3b8108 (&vcpu->mutex){+.+.}-{4:4}, at: kvm_vcpu_ioctl+0x77/0x6f0 [kvm]
[   89.138483]  #1: ffffa34a03662e90 (&kvm->srcu){....}-{0:0}, at: kvm_arch_vcpu_ioctl_run+0xdc/0x8b0 [kvm]
[   89.138526]  #2: ffff97331fdbac98 (&rq->__lock){-.-.}-{2:2}, at: __schedule+0xff/0xbd0
[   89.138534]  #3: ffffa34a03662e90 (&kvm->srcu){....}-{0:0}, at: kvm_arch_vcpu_put+0x26/0x170 [kvm]
...
[   89.138695]  get_kvmclock_ns+0x1f/0x130 [kvm]
[   89.138734]  kvm_xen_update_runstate+0x14/0x90 [kvm]
[   89.138783]  kvm_xen_update_runstate_guest+0x15/0xd0 [kvm]
[   89.138830]  kvm_arch_vcpu_put+0xe6/0x170 [kvm]
[   89.138870]  kvm_sched_out+0x2f/0x40 [kvm]
[   89.138900]  __schedule+0x5de/0xbd0

Cc: stable@vger.kernel.org
Reported-by: syzbot+b282b65c2c68492df769@syzkaller.appspotmail.com
Fixes: 30b5c851af ("KVM: x86/xen: Add support for vCPU runstate information")
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <1b02a06421c17993df337493a68ba923f3bd5c0f.camel@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-10-25 08:14:38 -04:00
..
alpha alpha: enable GENERIC_PCI_IOMAP unconditionally 2021-09-19 10:37:00 -07:00
arc Merge branch 'akpm' (patches from Andrew) 2021-09-08 12:55:35 -07:00
arm entry: rseq: Call rseq_handle_notify_resume() in tracehook_notify_resume() 2021-09-22 10:24:01 -04:00
arm64 KVM/arm64 fixes for 5.15, take #2 2021-10-15 04:47:55 -04:00
csky entry: rseq: Call rseq_handle_notify_resume() in tracehook_notify_resume() 2021-09-22 10:24:01 -04:00
h8300 Merge branch 'akpm' (patches from Andrew) 2021-09-08 12:55:35 -07:00
hexagon Merge branch 'akpm' (patches from Andrew) 2021-09-08 12:55:35 -07:00
ia64 Merge branch 'akpm' (patches from Andrew) 2021-09-08 12:55:35 -07:00
m68k m68k: mvme: Remove overdue #warnings in RTC handling 2021-09-13 11:19:05 +02:00
microblaze Microblaze patches for 5.15-rc1 2021-09-08 16:02:13 -07:00
mips entry: rseq: Call rseq_handle_notify_resume() in tracehook_notify_resume() 2021-09-22 10:24:01 -04:00
nds32 nds32/setup: remove unused memblock_region variable in setup_memory() 2021-09-08 18:45:53 -07:00
nios2 Merge branch 'akpm' (patches from Andrew) 2021-09-08 12:55:35 -07:00
openrisc Merge branch 'akpm' (patches from Andrew) 2021-09-08 12:55:35 -07:00
parisc parisc: Declare pci_iounmap() parisc version only when CONFIG_PCI enabled 2021-09-19 10:36:09 -07:00
powerpc entry: rseq: Call rseq_handle_notify_resume() in tracehook_notify_resume() 2021-09-22 10:24:01 -04:00
riscv Merge branch 'gcc-min-version-5.1' (make gcc-5.1 the minimum version) 2021-09-13 10:43:04 -07:00
s390 KVM: s390: Function documentation fixes 2021-09-28 17:56:54 +02:00
sh sh: Add missing FORCE prerequisites in Makefile 2021-09-19 10:13:42 +09:00
sparc dma-mapping fixes for Linux 5.15 2021-09-17 11:54:48 -07:00
um This pull request contains the following changes for UML: 2021-09-09 13:45:26 -07:00
x86 KVM: x86: switch pvclock_gtod_sync_lock to a raw spinlock 2021-10-25 08:14:38 -04:00
xtensa Tracing updates for 5.15: 2021-09-05 11:50:41 -07:00
.gitignore
Kconfig Merge branch 'akpm' (patches from Andrew) 2021-09-08 12:55:35 -07:00