[PATCH v2 13/13] RISC-V: KVM: Use NACL HFENCEs for KVM request based HFENCEs

[Atish Patra]

On Sun, Oct 20, 2024 at 12:48 PM Anup Patel <apatel at ventanamicro.com> wrote:
>
> When running under some other hypervisor, use SBI NACL based HFENCEs
> for TLB shoot-down via KVM requests. This makes HFENCEs faster whenever
> SBI nested acceleration is available.
>
> Signed-off-by: Anup Patel <apatel at ventanamicro.com>
> ---
>  arch/riscv/kvm/tlb.c | 57 +++++++++++++++++++++++++++++++-------------
>  1 file changed, 40 insertions(+), 17 deletions(-)
>
> diff --git a/arch/riscv/kvm/tlb.c b/arch/riscv/kvm/tlb.c
> index 23c0e82b5103..2f91ea5f8493 100644
> --- a/arch/riscv/kvm/tlb.c
> +++ b/arch/riscv/kvm/tlb.c
> @@ -14,6 +14,7 @@
>  #include <asm/csr.h>
>  #include <asm/cpufeature.h>
>  #include <asm/insn-def.h>
> +#include <asm/kvm_nacl.h>
>
>  #define has_svinval()  riscv_has_extension_unlikely(RISCV_ISA_EXT_SVINVAL)
>
> @@ -186,18 +187,24 @@ void kvm_riscv_fence_i_process(struct kvm_vcpu *vcpu)
>
>  void kvm_riscv_hfence_gvma_vmid_all_process(struct kvm_vcpu *vcpu)
>  {
> -       struct kvm_vmid *vmid;
> +       struct kvm_vmid *v = &vcpu->kvm->arch.vmid;
> +       unsigned long vmid = READ_ONCE(v->vmid);
>
> -       vmid = &vcpu->kvm->arch.vmid;
> -       kvm_riscv_local_hfence_gvma_vmid_all(READ_ONCE(vmid->vmid));
> +       if (kvm_riscv_nacl_available())
> +               nacl_hfence_gvma_vmid_all(nacl_shmem(), vmid);
> +       else
> +               kvm_riscv_local_hfence_gvma_vmid_all(vmid);
>  }
>
>  void kvm_riscv_hfence_vvma_all_process(struct kvm_vcpu *vcpu)
>  {
> -       struct kvm_vmid *vmid;
> +       struct kvm_vmid *v = &vcpu->kvm->arch.vmid;
> +       unsigned long vmid = READ_ONCE(v->vmid);
>
> -       vmid = &vcpu->kvm->arch.vmid;
> -       kvm_riscv_local_hfence_vvma_all(READ_ONCE(vmid->vmid));
> +       if (kvm_riscv_nacl_available())
> +               nacl_hfence_vvma_all(nacl_shmem(), vmid);
> +       else
> +               kvm_riscv_local_hfence_vvma_all(vmid);
>  }
>
>  static bool vcpu_hfence_dequeue(struct kvm_vcpu *vcpu,
> @@ -251,6 +258,7 @@ static bool vcpu_hfence_enqueue(struct kvm_vcpu *vcpu,
>
>  void kvm_riscv_hfence_process(struct kvm_vcpu *vcpu)
>  {
> +       unsigned long vmid;
>         struct kvm_riscv_hfence d = { 0 };
>         struct kvm_vmid *v = &vcpu->kvm->arch.vmid;
>
> @@ -259,26 +267,41 @@ void kvm_riscv_hfence_process(struct kvm_vcpu *vcpu)
>                 case KVM_RISCV_HFENCE_UNKNOWN:
>                         break;
>                 case KVM_RISCV_HFENCE_GVMA_VMID_GPA:
> -                       kvm_riscv_local_hfence_gvma_vmid_gpa(
> -                                               READ_ONCE(v->vmid),
> -                                               d.addr, d.size, d.order);
> +                       vmid = READ_ONCE(v->vmid);
> +                       if (kvm_riscv_nacl_available())
> +                               nacl_hfence_gvma_vmid(nacl_shmem(), vmid,
> +                                                     d.addr, d.size, d.order);
> +                       else
> +                               kvm_riscv_local_hfence_gvma_vmid_gpa(vmid, d.addr,
> +                                                                    d.size, d.order);
>                         break;
>                 case KVM_RISCV_HFENCE_VVMA_ASID_GVA:
>                         kvm_riscv_vcpu_pmu_incr_fw(vcpu, SBI_PMU_FW_HFENCE_VVMA_ASID_RCVD);
> -                       kvm_riscv_local_hfence_vvma_asid_gva(
> -                                               READ_ONCE(v->vmid), d.asid,
> -                                               d.addr, d.size, d.order);
> +                       vmid = READ_ONCE(v->vmid);
> +                       if (kvm_riscv_nacl_available())
> +                               nacl_hfence_vvma_asid(nacl_shmem(), vmid, d.asid,
> +                                                     d.addr, d.size, d.order);
> +                       else
> +                               kvm_riscv_local_hfence_vvma_asid_gva(vmid, d.asid, d.addr,
> +                                                                    d.size, d.order);
>                         break;
>                 case KVM_RISCV_HFENCE_VVMA_ASID_ALL:
>                         kvm_riscv_vcpu_pmu_incr_fw(vcpu, SBI_PMU_FW_HFENCE_VVMA_ASID_RCVD);
> -                       kvm_riscv_local_hfence_vvma_asid_all(
> -                                               READ_ONCE(v->vmid), d.asid);
> +                       vmid = READ_ONCE(v->vmid);
> +                       if (kvm_riscv_nacl_available())
> +                               nacl_hfence_vvma_asid_all(nacl_shmem(), vmid, d.asid);
> +                       else
> +                               kvm_riscv_local_hfence_vvma_asid_all(vmid, d.asid);
>                         break;
>                 case KVM_RISCV_HFENCE_VVMA_GVA:
>                         kvm_riscv_vcpu_pmu_incr_fw(vcpu, SBI_PMU_FW_HFENCE_VVMA_RCVD);
> -                       kvm_riscv_local_hfence_vvma_gva(
> -                                               READ_ONCE(v->vmid),
> -                                               d.addr, d.size, d.order);
> +                       vmid = READ_ONCE(v->vmid);
> +                       if (kvm_riscv_nacl_available())
> +                               nacl_hfence_vvma(nacl_shmem(), vmid,
> +                                                d.addr, d.size, d.order);
> +                       else
> +                               kvm_riscv_local_hfence_vvma_gva(vmid, d.addr,
> +                                                               d.size, d.order);
>                         break;
>                 default:
>                         break;
> --
> 2.43.0
>

Reviewed-by: Atish Patra <atishp at rivosinc.com>
-- 
Regards,
Atish