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. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel