linux-kernel - [PATCH 2/2] KVM: x86: Identify vCPU0 by its vcpu

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Date:   Fri, 10 Sep 2021 11:32:20 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] KVM: x86: Identify vCPU0 by its vcpu_idx instead of
 walking vCPUs array

Use vcpu_idx to identify vCPU0 when updating HyperV's TSC page, which is
shared by all vCPUs and "owned" by vCPU0 (because vCPU0 is the only vCPU
that's guaranteed to exist).  Using kvm_get_vcpu() to find vCPU works,
but it's a rather odd and suboptimal method to check the index of a given
vCPU.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/x86.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 86539c1686fa..6ab851df08d1 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2969,7 +2969,7 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)
 				       offsetof(struct compat_vcpu_info, time));
 	if (vcpu->xen.vcpu_time_info_set)
 		kvm_setup_pvclock_page(v, &vcpu->xen.vcpu_time_info_cache, 0);
-	if (v == kvm_get_vcpu(v->kvm, 0))
+	if (!v->vcpu_idx)
 		kvm_hv_setup_tsc_page(v->kvm, &vcpu->hv_clock);
 	return 0;
 }
-- 
2.33.0.309.g3052b89438-goog