Re: [RFC 5/5] LoongArch: KVM: Enable separate vmid feature

[Huacai Chen]

Hi, Bibo,

I think you need to probe LOONGARCH_CPU_GUESTID at the end of
cpu_probe_common(), otherwise cpu_has_guestid is always false.

Huacai

On Wed, Nov 13, 2024 at 11:17 AM Bibo Mao <maobibo@xxxxxxxxxxx> wrote:
>
> With CSR GTLBC shortname for Guest TLB Control Register, separate vmid
> feature will be enabled if bit 14 CSR_GTLBC_USEVMID is set. Enable
> this feature if cpu_has_guestid is true when KVM module is loaded.
>
> Signed-off-by: Bibo Mao <maobibo@xxxxxxxxxxx>
> ---
>  arch/loongarch/include/asm/loongarch.h | 2 ++
>  arch/loongarch/kvm/main.c              | 4 +++-
>  2 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/arch/loongarch/include/asm/loongarch.h b/arch/loongarch/include/asm/loongarch.h
> index 64ad277e096e..5fee5db3bea0 100644
> --- a/arch/loongarch/include/asm/loongarch.h
> +++ b/arch/loongarch/include/asm/loongarch.h
> @@ -326,6 +326,8 @@
>  #define  CSR_GTLBC_TGID_WIDTH          8
>  #define  CSR_GTLBC_TGID_SHIFT_END      (CSR_GTLBC_TGID_SHIFT + CSR_GTLBC_TGID_WIDTH - 1)
>  #define  CSR_GTLBC_TGID                        (_ULCAST_(0xff) << CSR_GTLBC_TGID_SHIFT)
> +#define  CSR_GTLBC_USEVMID_SHIFT       14
> +#define  CSR_GTLBC_USEVMID             (_ULCAST_(0x1) << CSR_GTLBC_USEVMID_SHIFT)
>  #define  CSR_GTLBC_TOTI_SHIFT          13
>  #define  CSR_GTLBC_TOTI                        (_ULCAST_(0x1) << CSR_GTLBC_TOTI_SHIFT)
>  #define  CSR_GTLBC_USETGID_SHIFT       12
> diff --git a/arch/loongarch/kvm/main.c b/arch/loongarch/kvm/main.c
> index f89d1df885d7..50c977d8b414 100644
> --- a/arch/loongarch/kvm/main.c
> +++ b/arch/loongarch/kvm/main.c
> @@ -336,7 +336,7 @@ int kvm_arch_enable_virtualization_cpu(void)
>         write_csr_gcfg(0);
>         write_csr_gstat(0);
>         write_csr_gintc(0);
> -       clear_csr_gtlbc(CSR_GTLBC_USETGID | CSR_GTLBC_TOTI);
> +       clear_csr_gtlbc(CSR_GTLBC_USETGID | CSR_GTLBC_TOTI | CSR_GTLBC_USEVMID);
>
>         /*
>          * Enable virtualization features granting guest direct control of
> @@ -359,6 +359,8 @@ int kvm_arch_enable_virtualization_cpu(void)
>
>         /* Enable using TGID  */
>         set_csr_gtlbc(CSR_GTLBC_USETGID);
> +       if (cpu_has_guestid)
> +               set_csr_gtlbc(CSR_GTLBC_USEVMID);
>         kvm_debug("GCFG:%lx GSTAT:%lx GINTC:%lx GTLBC:%lx",
>                   read_csr_gcfg(), read_csr_gstat(), read_csr_gintc(), read_csr_gtlbc());
>
> --
> 2.39.3
>