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KVM: x86: drop calling kvm_mmu_zap_all in emulator_fix_hypercall

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Quote Gleb's mail:

| Back then kvm->lock protected memslot access so code like:
|
| mutex_lock(&vcpu->kvm->lock);
| kvm_mmu_zap_all(vcpu->kvm);
| mutex_unlock(&vcpu->kvm->lock);
|
| which is what 7aa81cc0 does was enough to guaranty that no vcpu will
| run while code is patched. This is no longer the case and
| mutex_lock(&vcpu->kvm->lock); is gone from that code path long time ago,
| so now kvm_mmu_zap_all() there is useless and the code is incorrect.

So we drop it and it will be fixed later

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
This commit is contained in:
Xiao Guangrong 2013-05-31 08:36:20 +08:00 committed by Gleb Natapov
parent 6ea34c9b78
commit 758ccc89b8
1 changed files with 0 additions and 7 deletions
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7
arch/x86/kvm/x86.c
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@ -5523,13 +5523,6 @@ static int emulator_fix_hypercall(struct x86_emulate_ctxt *ctxt)
char instruction[3]; char instruction[3];
unsigned long rip = kvm_rip_read(vcpu); unsigned long rip = kvm_rip_read(vcpu);
/*
* Blow out the MMU to ensure that no other VCPU has an active mapping
* to ensure that the updated hypercall appears atomically across all
* VCPUs.
*/
kvm_mmu_zap_all(vcpu->kvm);
kvm_x86_ops->patch_hypercall(vcpu, instruction); kvm_x86_ops->patch_hypercall(vcpu, instruction);
return emulator_write_emulated(ctxt, rip, instruction, 3, NULL); return emulator_write_emulated(ctxt, rip, instruction, 3, NULL);