Re: [PATCH 1/3] target/riscv/cpu: ignore TCG init for KVM CPUs in reset_hold

[Alistair Francis]

On Fri, Feb 21, 2025 at 2:14 AM Daniel Henrique Barboza
<dbarboza@ventanamicro.com> wrote:
>
> riscv_cpu_reset_hold() does a lot of TCG-related initializations that
> aren't relevant for KVM, but nevertheless are impacting the reset state
> of KVM vcpus.
>
> When running a KVM guest, kvm_riscv_reset_vcpu() is called at the end of
> reset_hold(). At that point env->mstatus is initialized to a non-zero
> value, and it will be use to write 'sstatus' in the vcpu
> (kvm_arch_put_registers() then kvm_riscv_put_regs_csr()).
>
> Do an early exit in riscv_cpu_reset_hold() if we're running KVM. All the
> KVM reset procedure will be centered in kvm_riscv_reset_vcpu().
>
> While we're at it, remove the kvm_enabled() check in
> kvm_riscv_reset_vcpu() since it's already being gated in
> riscv_cpu_reset_hold().
>
> Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  target/riscv/cpu.c         | 9 +++++----
>  target/riscv/kvm/kvm-cpu.c | 3 ---
>  2 files changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index 522d6584e4..8e6e629ec4 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -1050,6 +1050,11 @@ static void riscv_cpu_reset_hold(Object *obj, 
> ResetType type)
>          mcc->parent_phases.hold(obj, type);
>      }
>  #ifndef CONFIG_USER_ONLY
> +    if (kvm_enabled()) {
> +        kvm_riscv_reset_vcpu(cpu);
> +        return;
> +    }
> +
>      env->misa_mxl = mcc->misa_mxl_max;
>      env->priv = PRV_M;
>      env->mstatus &= ~(MSTATUS_MIE | MSTATUS_MPRV);
> @@ -1146,10 +1151,6 @@ static void riscv_cpu_reset_hold(Object *obj, 
> ResetType type)
>          env->rnmip = 0;
>          env->mnstatus = set_field(env->mnstatus, MNSTATUS_NMIE, false);
>      }
> -
> -    if (kvm_enabled()) {
> -        kvm_riscv_reset_vcpu(cpu);
> -    }
>  #endif
>  }
>
> diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c
> index 23ce779359..484b6afe7c 100644
> --- a/target/riscv/kvm/kvm-cpu.c
> +++ b/target/riscv/kvm/kvm-cpu.c
> @@ -1603,9 +1603,6 @@ void kvm_riscv_reset_vcpu(RISCVCPU *cpu)
>      CPURISCVState *env = &cpu->env;
>      int i;
>
> -    if (!kvm_enabled()) {
> -        return;
> -    }
>      for (i = 0; i < 32; i++) {
>          env->gpr[i] = 0;
>      }
> --
> 2.48.1
>
>