linux-kernel - [RFC PATCH 18/28] KVM: arm64: Handle realm VCPU load

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Date:   Fri, 27 Jan 2023 11:29:22 +0000
From:   Steven Price <steven.price@....com>
To:     kvm@...r.kernel.org, kvmarm@...ts.linux.dev
Cc:     Steven Price <steven.price@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Marc Zyngier <maz@...nel.org>, Will Deacon <will@...nel.org>,
        James Morse <james.morse@....com>,
        Oliver Upton <oliver.upton@...ux.dev>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Zenghui Yu <yuzenghui@...wei.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Joey Gouly <joey.gouly@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Christoffer Dall <christoffer.dall@....com>,
        Fuad Tabba <tabba@...gle.com>, linux-coco@...ts.linux.dev
Subject: [RFC PATCH 18/28] KVM: arm64: Handle realm VCPU load

When loading a realm VCPU much of the work is handled by the RMM so only
some of the actions are required. Rearrange kvm_arch_vcpu_load()
slightly so we can bail out early for a realm guest.

Signed-off-by: Steven Price <steven.price@....com>
---
 arch/arm64/kvm/arm.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index fd9e28f48903..46c152a9a150 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -451,19 +451,25 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 
 	vcpu->cpu = cpu;
 
+	if (single_task_running())
+		vcpu_clear_wfx_traps(vcpu);
+	else
+		vcpu_set_wfx_traps(vcpu);
+
 	kvm_vgic_load(vcpu);
 	kvm_timer_vcpu_load(vcpu);
+
+	if (kvm_arm_is_pvtime_enabled(&vcpu->arch))
+		kvm_make_request(KVM_REQ_RECORD_STEAL, vcpu);
+
+	/* No additional state needs to be loaded on Realmed VMs */
+	if (vcpu_is_rec(vcpu))
+		return;
+
 	if (has_vhe())
 		kvm_vcpu_load_sysregs_vhe(vcpu);
 	kvm_arch_vcpu_load_fp(vcpu);
 	kvm_vcpu_pmu_restore_guest(vcpu);
-	if (kvm_arm_is_pvtime_enabled(&vcpu->arch))
-		kvm_make_request(KVM_REQ_RECORD_STEAL, vcpu);
-
-	if (single_task_running())
-		vcpu_clear_wfx_traps(vcpu);
-	else
-		vcpu_set_wfx_traps(vcpu);
 
 	if (vcpu_has_ptrauth(vcpu))
 		vcpu_ptrauth_disable(vcpu);
-- 
2.34.1