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| author | Paolo Bonzini <pbonzini@redhat.com> | 2014-11-02 07:54:30 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2014-11-02 08:37:18 +0100 |
| commit | a73896cb5bbdce672945745db8224352a689f580 (patch) | |
| tree | 15efc04f2fc6ae3fa04024263bbedfa45d68219c /arch | |
| parent | 282da870f4b5868efadcd4dc2a5a738d6fdf65d4 (diff) | |
| download | lwn-a73896cb5bbdce672945745db8224352a689f580.tar.gz lwn-a73896cb5bbdce672945745db8224352a689f580.zip | |
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: 38b9917350cb2946e368ba684cfc33d1672f104e
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kvm/vmx.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index a0f78dbaabee..3e556c68351b 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -4579,7 +4579,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu) vmcs_write32(TPR_THRESHOLD, 0); } - kvm_vcpu_reload_apic_access_page(vcpu); + kvm_make_request(KVM_REQ_APIC_PAGE_RELOAD, vcpu); if (vmx_vm_has_apicv(vcpu->kvm)) memset(&vmx->pi_desc, 0, sizeof(struct pi_desc)); |