linux/arch
Paolo Bonzini a73896cb5b KVM: vmx: defer load of APIC access page address during reset
Most call paths to vmx_vcpu_reset do not hold the SRCU lock.  Defer loading
the APIC access page to the next vmentry.

This avoids the following lockdep splat:

[ INFO: suspicious RCU usage. ]
3.18.0-rc2-test2+ #70 Not tainted
-------------------------------
include/linux/kvm_host.h:474 suspicious rcu_dereference_check() usage!

other info that might help us debug this:

rcu_scheduler_active = 1, debug_locks = 0
1 lock held by qemu-system-x86/2371:
 #0:  (&vcpu->mutex){+.+...}, at: [<ffffffffa037d800>] vcpu_load+0x20/0xd0 [kvm]

stack backtrace:
CPU: 4 PID: 2371 Comm: qemu-system-x86 Not tainted 3.18.0-rc2-test2+ #70
Hardware name: Dell Inc. OptiPlex 9010/0M9KCM, BIOS A12 01/10/2013
 0000000000000001 ffff880209983ca8 ffffffff816f514f 0000000000000000
 ffff8802099b8990 ffff880209983cd8 ffffffff810bd687 00000000000fee00
 ffff880208a2c000 ffff880208a10000 ffff88020ef50040 ffff880209983d08
Call Trace:
 [<ffffffff816f514f>] dump_stack+0x4e/0x71
 [<ffffffff810bd687>] lockdep_rcu_suspicious+0xe7/0x120
 [<ffffffffa037d055>] gfn_to_memslot+0xd5/0xe0 [kvm]
 [<ffffffffa03807d3>] __gfn_to_pfn+0x33/0x60 [kvm]
 [<ffffffffa0380885>] gfn_to_page+0x25/0x90 [kvm]
 [<ffffffffa038aeec>] kvm_vcpu_reload_apic_access_page+0x3c/0x80 [kvm]
 [<ffffffffa08f0a9c>] vmx_vcpu_reset+0x20c/0x460 [kvm_intel]
 [<ffffffffa039ab8e>] kvm_vcpu_reset+0x15e/0x1b0 [kvm]
 [<ffffffffa039ac0c>] kvm_arch_vcpu_setup+0x2c/0x50 [kvm]
 [<ffffffffa037f7e0>] kvm_vm_ioctl+0x1d0/0x780 [kvm]
 [<ffffffff810bc664>] ? __lock_is_held+0x54/0x80
 [<ffffffff812231f0>] do_vfs_ioctl+0x300/0x520
 [<ffffffff8122ee45>] ? __fget+0x5/0x250
 [<ffffffff8122f0fa>] ? __fget_light+0x2a/0xe0
 [<ffffffff81223491>] SyS_ioctl+0x81/0xa0
 [<ffffffff816fed6d>] system_call_fastpath+0x16/0x1b

Reported-by: Takashi Iwai <tiwai@suse.de>
Reported-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Reviewed-by: Wanpeng Li <wanpeng.li@linux.intel.com>
Tested-by: Wanpeng Li <wanpeng.li@linux.intel.com>
Fixes: 38b9917350
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-11-02 08:37:18 +01:00
..
alpha Merge git://git.infradead.org/users/eparis/audit 2014-10-19 16:25:56 -07:00
arc The "weak" attribute is commonly used for the default version of a 2014-10-23 15:04:27 -07:00
arm ARM: SoC fixes for -rc2 2014-10-26 11:35:51 -07:00
arm64 arm64 fixes: 2014-10-24 12:48:04 -07:00
avr32 Merge branch 'for-linus' of git://git.infradead.org/users/vkoul/slave-dma 2014-10-18 18:11:04 -07:00
blackfin Merge branch 'for-3.18-consistent-ops' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2014-10-15 07:48:18 +02:00
c6x
cris Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-10-13 16:23:15 +02:00
frv frv: remove unused declarations of __start___ex_table and __stop___ex_table 2014-10-14 02:18:28 +02:00
hexagon Merge branch 'locking-arch-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-10-13 15:48:00 +02:00
ia64 Merge branch 'x86-efi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-10-23 14:45:09 -07:00
m32r Merge branch 'locking-arch-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-10-13 15:48:00 +02:00
m68k Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu 2014-10-14 03:51:22 +02:00
metag Merge branch 'for-3.18-consistent-ops' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2014-10-15 07:48:18 +02:00
microblaze Merge git://git.infradead.org/users/eparis/audit 2014-10-19 16:25:56 -07:00
mips MIPS: SEAD3: Fix I2C device registration. 2014-10-24 13:34:42 +02:00
mn10300 Merge branch 'locking-arch-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-10-13 15:48:00 +02:00
openrisc Merge git://git.infradead.org/users/eparis/audit 2014-10-19 16:25:56 -07:00
parisc Merge git://git.infradead.org/users/eparis/audit 2014-10-19 16:25:56 -07:00
powerpc Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mpe/linux 2014-10-21 07:48:56 -07:00
s390 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux 2014-10-21 07:47:54 -07:00
score score: use Kbuild logic to include <asm-generic/sections.h> 2014-10-09 22:25:46 -04:00
sh Merge git://git.infradead.org/users/eparis/audit 2014-10-19 16:25:56 -07:00
sparc Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc 2014-10-24 12:45:47 -07:00
tile Merge branch 'for-3.18-consistent-ops' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2014-10-15 07:48:18 +02:00
um Merge git://git.infradead.org/users/eparis/audit 2014-10-19 16:25:56 -07:00
unicore32 nosave: consolidate __nosave_{begin,end} in <asm/sections.h> 2014-10-09 22:26:04 -04:00
x86 KVM: vmx: defer load of APIC access page address during reset 2014-11-02 08:37:18 +01:00
xtensa Merge git://git.infradead.org/users/eparis/audit 2014-10-19 16:25:56 -07:00
.gitignore
Kconfig