linux-kernel - [PATCH 4/7] KVM: x86: Don't load/put vCPU when unloading its MMU during teardown

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Message-ID: <20250224235542.2562848-5-seanjc@google.com>
Date: Mon, 24 Feb 2025 15:55:39 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
	Tianrui Zhao <zhaotianrui@...ngson.cn>, Bibo Mao <maobibo@...ngson.cn>, 
	Huacai Chen <chenhuacai@...nel.org>, Madhavan Srinivasan <maddy@...ux.ibm.com>, 
	Anup Patel <anup@...infault.org>, Paul Walmsley <paul.walmsley@...ive.com>, 
	Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	Christian Borntraeger <borntraeger@...ux.ibm.com>, Janosch Frank <frankja@...ux.ibm.com>, 
	Claudio Imbrenda <imbrenda@...ux.ibm.com>, Sean Christopherson <seanjc@...gle.com>, 
	Paolo Bonzini <pbonzini@...hat.com>
Cc: linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev, 
	kvm@...r.kernel.org, loongarch@...ts.linux.dev, linux-mips@...r.kernel.org, 
	linuxppc-dev@...ts.ozlabs.org, kvm-riscv@...ts.infradead.org, 
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	Aaron Lewis <aaronlewis@...gle.com>, Jim Mattson <jmattson@...gle.com>, 
	Yan Zhao <yan.y.zhao@...el.com>, Rick P Edgecombe <rick.p.edgecombe@...el.com>, 
	Kai Huang <kai.huang@...el.com>, Isaku Yamahata <isaku.yamahata@...el.com>
Subject: [PATCH 4/7] KVM: x86: Don't load/put vCPU when unloading its MMU
 during teardown

Don't load (and then put) a vCPU when unloading its MMU during VM
destruction, as nothing in kvm_mmu_unload() accesses vCPU state beyond the
root page/address of each MMU, i.e. can't possible need to run with the
vCPU loaded.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/x86.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 045c61cc7e54..9978ed4c0917 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -12767,13 +12767,6 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 	return ret;
 }
 
-static void kvm_unload_vcpu_mmu(struct kvm_vcpu *vcpu)
-{
-	vcpu_load(vcpu);
-	kvm_mmu_unload(vcpu);
-	vcpu_put(vcpu);
-}
-
 static void kvm_unload_vcpu_mmus(struct kvm *kvm)
 {
 	unsigned long i;
@@ -12781,7 +12774,7 @@ static void kvm_unload_vcpu_mmus(struct kvm *kvm)
 
 	kvm_for_each_vcpu(i, vcpu, kvm) {
 		kvm_clear_async_pf_completion_queue(vcpu);
-		kvm_unload_vcpu_mmu(vcpu);
+		kvm_mmu_unload(vcpu);
 	}
 }
 
-- 
2.48.1.658.g4767266eb4-goog