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authorPaolo Bonzini <pbonzini@redhat.com>2014-11-02 09:54:30 +0300
committerPaolo Bonzini <pbonzini@redhat.com>2014-11-02 10:37:18 +0300
commita73896cb5bbdce672945745db8224352a689f580 (patch)
tree15efc04f2fc6ae3fa04024263bbedfa45d68219c
parent282da870f4b5868efadcd4dc2a5a738d6fdf65d4 (diff)
downloadlinux-a73896cb5bbdce672945745db8224352a689f580.tar.xz
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>
-rw-r--r--arch/x86/kvm/vmx.c2
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));