Re: [PATCH v2 3/5] LoongArch: KVM: Add separate vmid feature support

[Huacai Chen]

Hi, Bibo,

On Thu, Aug 6, 2026 at 10:15 AM Bibo Mao <maobibo@xxxxxxxxxxx> wrote:
>
> Feature cpu_has_guestid is used to check whether separate vmid/vpid
> is supported or not. It is disabled by default, add this feature
> checking, there is no function change.
>
> Signed-off-by: Bibo Mao <maobibo@xxxxxxxxxxx>
> ---
>  arch/loongarch/kvm/main.c | 14 +++++++++-----
>  arch/loongarch/kvm/mmu.c  |  6 ++++--
>  arch/loongarch/kvm/vcpu.c |  3 ++-
>  3 files changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/arch/loongarch/kvm/main.c b/arch/loongarch/kvm/main.c
> index ac804e77e844..c36e62ab0d91 100644
> --- a/arch/loongarch/kvm/main.c
> +++ b/arch/loongarch/kvm/main.c
> @@ -218,7 +218,8 @@ static void kvm_update_vpid(struct kvm_vcpu *vcpu, int cpu)
>                 ++vpid; /* vpid 0 reserved for root */
>
>                 /* start new vpid cycle */
> -               kvm_flush_tlb_all();
> +               if (!cpu_has_guestid)
> +                       kvm_flush_tlb_all();
>         }
>
>         context->vpid_cache = vpid;
> @@ -282,10 +283,13 @@ static void __kvm_check_vmid(struct kvm_vcpu *vcpu)
>  {
>         unsigned long vmid;
>
> -       vmid = vcpu->arch.vpid & vpid_mask;
> -       if (vcpu->arch.hw_vmid != vmid) {
> -               vcpu->arch.hw_vmid = vcpu->arch.vpid & vpid_mask;
> -               kvm_clear_request(KVM_REQ_TLB_FLUSH_GPA, vcpu);
> +       /* On some machines like 3A5000, vmid needs the same with vpid */
> +       if (!cpu_has_guestid) {
> +               vmid = vcpu->arch.vpid & vpid_mask;
> +               if (vcpu->arch.hw_vmid != vmid) {
> +                       vcpu->arch.hw_vmid = vcpu->arch.vpid & vpid_mask;
> +                       kvm_clear_request(KVM_REQ_TLB_FLUSH_GPA, vcpu);
> +               }
Merge Patch#3 and Patch#4, then __kvm_check_vmid() can handle both
cpu_has_guestid and !cpu_has_guestid cases together.


Huacai

>         }
>  }
>
> diff --git a/arch/loongarch/kvm/mmu.c b/arch/loongarch/kvm/mmu.c
> index e104897aa532..714640a2e614 100644
> --- a/arch/loongarch/kvm/mmu.c
> +++ b/arch/loongarch/kvm/mmu.c
> @@ -929,8 +929,10 @@ int kvm_handle_mm_fault(struct kvm_vcpu *vcpu, unsigned long gpa, bool write, in
>                  *
>                  * With SW PTW, invalid TLB is added in TLB refill exception.
>                  */
> -               vcpu->arch.flush_gpa = gpa;
> -               kvm_make_request(KVM_REQ_TLB_FLUSH_GPA, vcpu);
> +               if (!cpu_has_guestid) {
> +                       vcpu->arch.flush_gpa = gpa;
> +                       kvm_make_request(KVM_REQ_TLB_FLUSH_GPA, vcpu);
> +               }
>         }
>
>         return 0;
> diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c
> index 20c207d80e31..0b2355aec932 100644
> --- a/arch/loongarch/kvm/vcpu.c
> +++ b/arch/loongarch/kvm/vcpu.c
> @@ -210,7 +210,8 @@ static int kvm_check_requests(struct kvm_vcpu *vcpu)
>                 return RESUME_GUEST;
>
>         if (kvm_check_request(KVM_REQ_TLB_FLUSH, vcpu))
> -               vcpu->arch.vpid = 0;  /* Drop vpid for this vCPU */
> +               if (!cpu_has_guestid)
> +                       vcpu->arch.vpid = 0;  /* Drop vpid for this vCPU */
>
>         if (kvm_dirty_ring_check_request(vcpu))
>                 return RESUME_HOST;
> --
> 2.39.3
>