Re: [PATCH] KVM: x86: fix access memslots w/o hold srcu read lock

From: Wanpeng Li
Date: Fri Oct 31 2014 - 22:50:03 EST


Hi Paolo,
On 14/10/31 äå6:36, Paolo Bonzini wrote:

On 31/10/2014 06:30, Chen, Tiejun wrote:
@@ -4442,6 +4442,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
struct msr_data apic_base_msr;
+ int idx;

vmx->rmode.vm86_active = 0;

@@ -4509,7 +4510,9 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu)
vmcs_write32(TPR_THRESHOLD, 0);
}

+ idx = srcu_read_lock(&vcpu->kvm->srcu);
kvm_vcpu_reload_apic_access_page(vcpu);
+ srcu_read_unlock(&vcpu->kvm->srcu, idx);

if (vmx_vm_has_apicv(vcpu->kvm))
memset(&vmx->pi_desc, 0, sizeof(struct pi_desc));
Not enough; you can call vcpu_enter_guest -> kvm_apic_accept_events ->
kvm_vcpu_reset -> vmx_vcpu_reset while under the SRCU lock. The right
place to add the lock is kvm_arch_vcpu_setup.

This is also not enough. I see the warning in the below path during the test:

kvm_arch_vcpu_ioctl_run
-> kvm_apic_accept_events
-> kvm_vcpu_reset

I just send out the version 3 and hope it can take care all the situations. ;-)

Regards,
Wanpeng Li


Thanks,

Paolo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/