linux-kernel - Re: [PATCH] KVM: vmx: fix VPID is 0000H in non-root operation

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Date:	Wed, 16 Sep 2015 14:42:30 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Jan Kiszka <jan.kiszka@...mens.com>,
	Wanpeng Li <wanpeng.li@...mail.com>
Cc:	Bandan Das <bsd@...hat.com>, Wincy Van <fanwenyi0529@...il.com>,
	kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: vmx: fix VPID is 0000H in non-root operation



On 16/09/2015 14:32, Jan Kiszka wrote:
> 
> BTW, what will happen if allocate_vpid runs out of free slots and
> returns 0? Will we always fail then...?

The return value of vmx_secondary_exec_control will not have
SECONDARY_EXEC_ENABLE_VPID, so it's okay.  However, I think
we need this in the nested VPID patches:

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index c23482cda1a7..e6859b45b00b 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -9456,7 +9460,7 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
 	else
 		vmcs_write64(TSC_OFFSET, vmx->nested.vmcs01_tsc_offset);
 
-	if (enable_vpid) {
+	if (vmx->nested.vpid02) {
 		/*
 		 * There is no direct mapping between vpid02 and vpid12, the
 		 * vpid02 is per-vCPU for L0 and reused while the value of

Paolo
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