[PATCH] KVM: VMX: Do not overwrite vcpu->srcu_idx in vmx_vcpu_reset

[Jan Kiszka <jan.kiszka@siemens.com>]

vmx_vcpu_reset may now be called while already holding the srcu lock, so
we may overwrite what was already saved there. Also, we lock and unlock
in the same context, thus there was no need to save to the vcpu anyway.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---

Marcelo just suggested this as the simplest fix for the issue caused by
the INIT/SIPI patch. Avoiding srcu lock for TSS handling might still be
possible but more tricky.

 arch/x86/kvm/vmx.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 958ac3a..be5b1dc 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -4117,6 +4117,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 	u64 msr;
+	int idx;
 
 	vmx->rmode.vm86_active = 0;
 
@@ -4190,9 +4191,9 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu)
 		vmcs_write16(VIRTUAL_PROCESSOR_ID, vmx->vpid);
 
 	vmx->vcpu.arch.cr0 = X86_CR0_NW | X86_CR0_CD | X86_CR0_ET;
-	vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
+	idx = srcu_read_lock(&vcpu->kvm->srcu);
 	vmx_set_cr0(&vmx->vcpu, kvm_read_cr0(vcpu)); /* enter rmode */
-	srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
+	srcu_read_unlock(&vcpu->kvm->srcu, idx);
 	vmx_set_cr4(&vmx->vcpu, 0);
 	vmx_set_efer(&vmx->vcpu, 0);
 	vmx_fpu_activate(&vmx->vcpu);
-- 
1.7.3.4