Thread (28 messages) flat view 28 messages, 3 authors, 2021-10-19

Re: [PATCH 03/16] KVM: arm64: Avoid remapping the SVE state in the hyp stage-1

From: Marc Zyngier <maz@kernel.org>
Date: 2021-10-16 11:04:25
Also in: kvmarm, lkml

On Wed, 13 Oct 2021 16:58:18 +0100,
Quentin Perret [off-list ref] wrote:
quoted hunk ↗ jump to hunk
We currently map the SVE state into the hypervisor stage-1 on VCPU_RUN,
when the vCPU thread's PID has changed. However, this only needs to be
done during the first VCPU_RUN as the SVE state doesn't depend on
thread-specific data, so move the create_hyp_mapping() call to
kvm_vcpu_first_run_init().

Suggested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Quentin Perret <redacted>
---
 arch/arm64/kvm/arm.c    | 12 ++++++++++++
 arch/arm64/kvm/fpsimd.c | 11 -----------
 2 files changed, 12 insertions(+), 11 deletions(-)
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index fe102cd2e518..c33d8c073820 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -618,6 +618,18 @@ static int kvm_vcpu_first_run_init(struct kvm_vcpu *vcpu)
 	if (ret)
 		return ret;
 
+	if (vcpu->arch.sve_state) {
+		void *sve_end;
+
+		sve_end = vcpu->arch.sve_state + vcpu_sve_state_size(vcpu);
+
+		ret = create_hyp_mappings(vcpu->arch.sve_state, sve_end,
+					  PAGE_HYP);
+		if (ret)
+			return ret;
+	}
+
+
 	ret = kvm_arm_pmu_v3_enable(vcpu);
 
 	return ret;
diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c
index 5621020b28de..62c0d78da7be 100644
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -43,17 +43,6 @@ int kvm_arch_vcpu_run_map_fp(struct kvm_vcpu *vcpu)
 	if (ret)
 		goto error;
 
-	if (vcpu->arch.sve_state) {
-		void *sve_end;
-
-		sve_end = vcpu->arch.sve_state + vcpu_sve_state_size(vcpu);
-
-		ret = create_hyp_mappings(vcpu->arch.sve_state, sve_end,
-					  PAGE_HYP);
-		if (ret)
-			goto error;
-	}
-
 	vcpu->arch.host_thread_info = kern_hyp_va(ti);
 	vcpu->arch.host_fpsimd_state = kern_hyp_va(fpsimd);
 error:
I actually ended-up implementing a similar patch as part of my 'first
run' series[1], though I moved the mapping to the point where we
finalise the vcpu as that's where the allocation takes place.

Do you see any potential issue with that approach?

Thanks,

	M.

[1] https://lore.kernel.org/r/20211015090822.2994920-2-maz@kernel.org (local)

-- 
Without deviation from the norm, progress is not possible.

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