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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>,
	Jing Zhang <jingzhangos@google.com>,
	Reiji Watanabe <reijiw@google.com>,
	Oliver Upton <oliver.upton@linux.dev>
Subject: [PATCH 4/4] KVM: arm64: Always return generic v8 as the preferred target
Date: Fri, 23 Jun 2023 19:42:58 +0000	[thread overview]
Message-ID: <20230623194258.2648987-5-oliver.upton@linux.dev> (raw)
In-Reply-To: <20230623194258.2648987-1-oliver.upton@linux.dev>

Userspace selecting an implementation-specific vCPU target has been
completely useless for a very long time. Let's go whole hog and start
returning the generic v8 target across all implementations as the
preferred target.

Uphold the pre-existing behavior by tolerating either the generic target
or an implementation-specific target if the vCPU happens to be running
on one of the lucky few parts.

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
 arch/arm64/kvm/arm.c   | 3 ++-
 arch/arm64/kvm/guest.c | 4 +---
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 3fa63fdbbf34..5a3b8b2e779b 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1250,7 +1250,8 @@ static int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
 {
 	int ret;
 
-	if (init->target != kvm_target_cpu())
+	if (init->target != KVM_ARM_TARGET_GENERIC_V8 &&
+	    init->target != kvm_target_cpu())
 		return -EINVAL;
 
 	ret = kvm_vcpu_init_check_features(vcpu, init);
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 20280a5233f6..6b099a914fd4 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -886,8 +886,6 @@ u32 __attribute_const__ kvm_target_cpu(void)
 
 void kvm_vcpu_preferred_target(struct kvm_vcpu_init *init)
 {
-	u32 target = kvm_target_cpu();
-
 	memset(init, 0, sizeof(*init));
 
 	/*
@@ -896,7 +894,7 @@ void kvm_vcpu_preferred_target(struct kvm_vcpu_init *init)
 	 * specific features available for the preferred
 	 * target type.
 	 */
-	init->target = (__u32)target;
+	init->target = KVM_ARM_TARGET_GENERIC_V8;
 }
 
 int kvm_arch_vcpu_ioctl_get_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
-- 
2.41.0.178.g377b9f9a00-goog


  parent reply	other threads:[~2023-06-23 19:43 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-23 19:42 [PATCH 0/4] KVM: arm64: Consistently use 'generic' vCPU target across all uarches Oliver Upton
2023-06-23 19:42 ` [PATCH 1/4] KVM: arm64: Delete pointless switch statement in kvm_reset_vcpu() Oliver Upton
2023-07-10 15:14   ` Zenghui Yu
2023-06-23 19:42 ` [PATCH 2/4] KVM: arm64: Remove pointless check for changed init target Oliver Upton
2023-06-23 19:42 ` [PATCH 3/4] KVM: arm64: Replace vCPU target with a configuration flag Oliver Upton
2023-07-10 15:17   ` Zenghui Yu
2023-06-23 19:42 ` Oliver Upton [this message]
2023-06-24  0:45   ` [PATCH 4/4] KVM: arm64: Always return generic v8 as the preferred target Marc Zyngier
2023-06-24  0:55     ` Oliver Upton
2023-07-10 15:13   ` Zenghui Yu
2023-07-10 18:35     ` Oliver Upton

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