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Hou Wenlong 6a0c61703e KVM: eventfd: Fix false positive RCU usage warning
Fix the following false positive warning:
 =============================
 WARNING: suspicious RCU usage
 5.16.0-rc4+ #57 Not tainted
 -----------------------------
 arch/x86/kvm/../../../virt/kvm/eventfd.c:484 RCU-list traversed in non-reader section!!

 other info that might help us debug this:

 rcu_scheduler_active = 2, debug_locks = 1
 3 locks held by fc_vcpu 0/330:
  #0: ffff8884835fc0b0 (&vcpu->mutex){+.+.}-{3:3}, at: kvm_vcpu_ioctl+0x88/0x6f0 [kvm]
  #1: ffffc90004c0bb68 (&kvm->srcu){....}-{0:0}, at: vcpu_enter_guest+0x600/0x1860 [kvm]
  #2: ffffc90004c0c1d0 (&kvm->irq_srcu){....}-{0:0}, at: kvm_notify_acked_irq+0x36/0x180 [kvm]

 stack backtrace:
 CPU: 26 PID: 330 Comm: fc_vcpu 0 Not tainted 5.16.0-rc4+
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
 Call Trace:
  <TASK>
  dump_stack_lvl+0x44/0x57
  kvm_notify_acked_gsi+0x6b/0x70 [kvm]
  kvm_notify_acked_irq+0x8d/0x180 [kvm]
  kvm_ioapic_update_eoi+0x92/0x240 [kvm]
  kvm_apic_set_eoi_accelerated+0x2a/0xe0 [kvm]
  handle_apic_eoi_induced+0x3d/0x60 [kvm_intel]
  vmx_handle_exit+0x19c/0x6a0 [kvm_intel]
  vcpu_enter_guest+0x66e/0x1860 [kvm]
  kvm_arch_vcpu_ioctl_run+0x438/0x7f0 [kvm]
  kvm_vcpu_ioctl+0x38a/0x6f0 [kvm]
  __x64_sys_ioctl+0x89/0xc0
  do_syscall_64+0x3a/0x90
  entry_SYSCALL_64_after_hwframe+0x44/0xae

Since kvm_unregister_irq_ack_notifier() does synchronize_srcu(&kvm->irq_srcu),
kvm->irq_ack_notifier_list is protected by kvm->irq_srcu. In fact,
kvm->irq_srcu SRCU read lock is held in kvm_notify_acked_irq(), making it
a false positive warning. So use hlist_for_each_entry_srcu() instead of
hlist_for_each_entry_rcu().

Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Hou Wenlong <houwenlong93@linux.alibaba.com>
Message-Id: <f98bac4f5052bad2c26df9ad50f7019e40434512.1643265976.git.houwenlong.hwl@antgroup.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-01-28 07:38:27 -05:00
arch KVM: nVMX: Allow VMREAD when Enlightened VMCS is in use 2022-01-28 07:38:26 -05:00
block
certs
crypto
Documentation KVM: x86: add system attribute to retrieve full set of supported xsave states 2022-01-28 07:33:32 -05:00
drivers Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2022-01-09 10:49:12 -08:00
fs Fixes for 5.16-rc8: 2022-01-08 10:56:47 -08:00
include KVM: x86: add system attribute to retrieve full set of supported xsave states 2022-01-28 07:33:32 -05:00
init
ipc
kernel Merge branch 'for-5.16-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2022-01-07 15:58:06 -08:00
lib
LICENSES
mm
net
samples ftrace/samples: Add missing prototypes direct functions 2022-01-05 18:34:50 -05:00
scripts
security
sound
tools selftests: kvm: check dynamic bits against KVM_X86_XCOMP_GUEST_SUPP 2022-01-28 07:38:25 -05:00
usr
virt KVM: eventfd: Fix false positive RCU usage warning 2022-01-28 07:38:27 -05:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap Merge branch 'kvm-pi-raw-spinlock' into HEAD 2022-01-19 12:14:02 -05:00
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Merge branch 'kvm-pi-raw-spinlock' into HEAD 2022-01-19 12:14:02 -05:00
Makefile Linux 5.16 2022-01-09 14:55:34 -08:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.