linux-kernel - [PATCH kvmtool v4 06/15] arm64: Use KVM_SET_MP

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Message-ID: <20250930103130.197534-8-suzuki.poulose@arm.com>
Date: Tue, 30 Sep 2025 11:31:21 +0100
From: Suzuki K Poulose <suzuki.poulose@....com>
To: kvmarm@...ts.linux.dev
Cc: kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	will@...nel.org,
	oliver.upton@...ux.dev,
	maz@...nel.org,
	alexandru.elisei@....com,
	aneesh.kumar@...nel.org,
	steven.price@....com,
	tabba@...gle.com,
	Suzuki K Poulose <suzuki.poulose@....com>
Subject: [PATCH kvmtool v4 06/15] arm64: Use KVM_SET_MP_STATE ioctl to power off non-boot vCPUs

From: Oliver Upton <oliver.upton@...ux.dev>

Using the POWER_OFF flag in kvm_vcpu_init gets in the way of resetting a
vCPU in response to a PSCI CPU_ON call, for obvious reasons. Drop the
flag in favor of using the KVM_SET_MP_STATE call for non-boot vCPUs.

Signed-off-by: Oliver Upton <oliver.upton@...ux.dev>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
---
 arm64/kvm-cpu.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/arm64/kvm-cpu.c b/arm64/kvm-cpu.c
index 3d914112..c7286484 100644
--- a/arm64/kvm-cpu.c
+++ b/arm64/kvm-cpu.c
@@ -143,10 +143,6 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm *kvm, unsigned long cpu_id)
 	if (vcpu->kvm_run == MAP_FAILED)
 		die("unable to mmap vcpu fd");
 
-	/* VCPU 0 is the boot CPU, the others start in a poweroff state. */
-	if (cpu_id > 0)
-		vcpu_init.features[0] |= (1UL << KVM_ARM_VCPU_POWER_OFF);
-
 	/* Set KVM_ARM_VCPU_PSCI_0_2 if available */
 	if (kvm__supports_extension(kvm, KVM_CAP_ARM_PSCI_0_2)) {
 		vcpu_init.features[0] |= (1UL << KVM_ARM_VCPU_PSCI_0_2);
@@ -201,6 +197,16 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm *kvm, unsigned long cpu_id)
 	if (err || target->init(vcpu))
 		die("Unable to initialise vcpu");
 
+	/* VCPU 0 is the boot CPU, the others start in a poweroff state. */
+	if (cpu_id > 0) {
+		struct kvm_mp_state mp_state = {
+			.mp_state	= KVM_MP_STATE_STOPPED,
+		};
+
+		if (ioctl(vcpu->vcpu_fd, KVM_SET_MP_STATE, &mp_state))
+			die_perror("KVM_SET_MP_STATE failed");
+	}
+
 	coalesced_offset = ioctl(kvm->sys_fd, KVM_CHECK_EXTENSION,
 				 KVM_CAP_COALESCED_MMIO);
 	if (coalesced_offset)
-- 
2.43.0