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From: Oliver Upton <oliver.upton@linux.dev>
To: kvmarm@lists.linux.dev
Cc: Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Zenghui Yu <yuzenghui@huawei.com>, Will Deacon <will@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Fuad Tabba <tabba@google.com>,
	linux-arm-kernel@lists.infradead.org, surajjs@amazon.com,
	Cornelia Huck <cohuck@redhat.com>,
	Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>,
	Jing Zhang <jingzhangos@google.com>,
	Oliver Upton <oliver.upton@linux.dev>
Subject: [PATCH v12 02/11] KVM: arm64: Relax invariance of KVM_ARM_VCPU_POWER_OFF
Date: Fri,  9 Jun 2023 19:00:45 +0000	[thread overview]
Message-ID: <20230609190054.1542113-3-oliver.upton@linux.dev> (raw)
In-Reply-To: <20230609190054.1542113-1-oliver.upton@linux.dev>

Allow the value of KVM_ARM_VCPU_POWER_OFF to differ between calls to
KVM_ARM_VCPU_INIT. Userspace can already change the state of the vCPU
through the KVM_SET_MP_STATE ioctl, so making the bit invariant seems
needlessly restrictive.

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
 arch/arm64/kvm/arm.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index d5298054a8ed..a9c18f45df3f 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1236,8 +1236,19 @@ static int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
 static int kvm_arch_vcpu_ioctl_vcpu_init(struct kvm_vcpu *vcpu,
 					 struct kvm_vcpu_init *init)
 {
+	bool power_off = false;
 	int ret;
 
+	/*
+	 * Treat the power-off vCPU feature as ephemeral. Clear the bit to avoid
+	 * reflecting it in the finalized feature set, thus limiting its scope
+	 * to a single KVM_ARM_VCPU_INIT call.
+	 */
+	if (init->features[0] & KVM_ARM_VCPU_POWER_OFF) {
+		init->features[0] &= ~KVM_ARM_VCPU_POWER_OFF;
+		power_off = true;
+	}
+
 	ret = kvm_vcpu_set_target(vcpu, init);
 	if (ret)
 		return ret;
@@ -1266,7 +1277,7 @@ static int kvm_arch_vcpu_ioctl_vcpu_init(struct kvm_vcpu *vcpu,
 	 */
 	spin_lock(&vcpu->arch.mp_state_lock);
 
-	if (test_bit(KVM_ARM_VCPU_POWER_OFF, vcpu->arch.features))
+	if (power_off)
 		__kvm_arm_vcpu_power_off(vcpu);
 	else
 		WRITE_ONCE(vcpu->arch.mp_state.mp_state, KVM_MP_STATE_RUNNABLE);
-- 
2.41.0.162.gfafddb0af9-goog


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  parent reply	other threads:[~2023-06-09 19:01 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-09 19:00 [PATCH v12 00/11] Support writable CPU ID registers from userspace Oliver Upton
2023-06-09 19:00 ` [PATCH v12 01/11] KVM: arm64: Separate out feature sanitisation and initialisation Oliver Upton
2023-06-09 19:00 ` Oliver Upton [this message]
2023-06-09 19:00 ` [PATCH v12 03/11] KVM: arm64: Make vCPU feature flags consistent VM-wide Oliver Upton
2023-06-09 19:00 ` [PATCH v12 04/11] KVM: arm64: Rewrite IMPDEF PMU version as NI Oliver Upton
2023-06-09 19:00 ` [PATCH v12 05/11] KVM: arm64: Reuse fields of sys_reg_desc for idreg Oliver Upton
2023-06-09 19:00 ` [PATCH v12 06/11] KVM: arm64: Save ID registers' sanitized value per guest Oliver Upton
2023-06-09 19:00 ` [PATCH v12 07/11] KVM: arm64: Use arm64_ftr_bits to sanitise ID register writes Oliver Upton
2023-06-15 12:38   ` Marc Zyngier
2023-06-15 12:45     ` Oliver Upton
2023-06-09 19:00 ` [PATCH v12 08/11] KVM: arm64: Use generic sanitisation for ID_(AA64)DFR0_EL1 Oliver Upton
2023-06-09 19:00 ` [PATCH v12 09/11] KVM: arm64: Use generic sanitisation for ID_AA64PFR0_EL1 Oliver Upton
2023-06-09 19:00 ` [PATCH v12 10/11] KVM: arm64: Handle ID register reads using the VM-wide values Oliver Upton
2023-06-09 19:00 ` [PATCH v12 11/11] KVM: arm64: Rip out the vestiges of the 'old' ID register scheme Oliver Upton
2023-06-09 19:08 ` [PATCH v12 00/11] Support writable CPU ID registers from userspace Oliver Upton
2023-06-15 13:20 ` Oliver Upton
2023-06-15 13:30 ` Marc Zyngier

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