linux-kernel - [PATCH v2 5/6] KVM: x86: Unconditionally set l1tf_flush

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Date: Tue, 21 May 2024 18:40:12 -0700
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>, Michael Ellerman <mpe@...erman.id.au>, 
	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
Subject: [PATCH v2 5/6] KVM: x86: Unconditionally set l1tf_flush_l1d during
 vCPU load

Always set l1tf_flush_l1d during kvm_arch_vcpu_load() instead of setting
it only when the vCPU is being scheduled back in.  The flag is processed
only when VM-Enter is imminent, and KVM obviously needs to load the vCPU
before VM-Enter, so attempting to precisely set l1tf_flush_l1d provides no
meaningful value.  I.e. the flag _will_ be set either way, it's simply a
matter of when.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/x86.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 59aa772af755..60fea297f91f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5006,12 +5006,11 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 {
 	struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
 
-	if (vcpu->scheduled_out) {
-		vcpu->arch.l1tf_flush_l1d = true;
-		if (pmu->version && unlikely(pmu->event_count)) {
-			pmu->need_cleanup = true;
-			kvm_make_request(KVM_REQ_PMU, vcpu);
-		}
+	vcpu->arch.l1tf_flush_l1d = true;
+
+	if (vcpu->scheduled_out && pmu->version && pmu->event_count) {
+		pmu->need_cleanup = true;
+		kvm_make_request(KVM_REQ_PMU, vcpu);
 	}
 
 	/* Address WBINVD may be executed by guest */
-- 
2.45.0.215.g3402c0e53f-goog