[PATCH 2/4] KVM: arm64: Do not clear VM-wide SVE feature on vCPU init failure

[Fuad Tabba <fuad.tabba@linux.dev>]

pkvm_vcpu_init_sve() clears KVM_ARM_VCPU_SVE in kvm->arch.vcpu_features
when it fails, but vcpu_has_sve() tests KVM_ARCH_FLAG_GUEST_HAS_SVE,
which is left set. Later vCPUs on that VM then skip the SVE setup and
register with a NULL sve_state, which the guest's first FP access hands
to sve_load_state().

Return the error without touching vcpu_features.

Fixes: 5db1bef93342 ("KVM: arm64: Track SVE state in the hypervisor vcpu structure")
Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
---
 arch/arm64/kvm/hyp/nvhe/pkvm.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c
index 095ebfce91b08..73e6ee059eebb 100644
--- a/arch/arm64/kvm/hyp/nvhe/pkvm.c
+++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c
@@ -451,7 +451,7 @@ static int pkvm_vcpu_init_sve(struct pkvm_hyp_vcpu *hyp_vcpu, struct kvm_vcpu *h
 	unsigned int sve_max_vl;
 	size_t sve_state_size;
 	void *sve_state;
-	int ret = 0;
+	int ret;
 
 	if (!vcpu_has_feature(vcpu, KVM_ARM_VCPU_SVE)) {
 		vcpu_clear_flag(vcpu, VCPU_SVE_FINALIZED);
@@ -462,24 +462,19 @@ static int pkvm_vcpu_init_sve(struct pkvm_hyp_vcpu *hyp_vcpu, struct kvm_vcpu *h
 	sve_max_vl = min(READ_ONCE(host_vcpu->arch.sve_max_vl), kvm_host_sve_max_vl);
 	sve_state = kern_hyp_va(READ_ONCE(host_vcpu->arch.sve_state));
 
-	if (!sve_vl_valid(sve_max_vl) || !sve_state) {
-		ret = -EINVAL;
-		goto err;
-	}
+	if (!sve_vl_valid(sve_max_vl) || !sve_state)
+		return -EINVAL;
 
 	sve_state_size = sve_state_size_from_vl(sve_max_vl);
 
 	ret = hyp_pin_shared_mem(sve_state, sve_state + sve_state_size);
 	if (ret)
-		goto err;
+		return ret;
 
 	vcpu->arch.sve_state = sve_state;
 	vcpu->arch.sve_max_vl = sve_max_vl;
 
 	return 0;
-err:
-	clear_bit(KVM_ARM_VCPU_SVE, vcpu->kvm->arch.vcpu_features);
-	return ret;
 }
 
 static int vm_copy_id_regs(struct pkvm_hyp_vcpu *hyp_vcpu)
-- 
2.39.5