Re: [PATCH v3 15/17] RISC-V: KVM: add SBI extension reset callback

Andrew Jones
2025-03-13T14:29:05Z

On Mon, Mar 10, 2025 at 04:12:22PM +0100, Clément Léger wrote:
> Currently, oonly the STA extension needed a reset function but that's

only

> going to be the case for FWFT as well. Add a reset callback that can be
> implemented by SBI extensions.
>
> Signed-off-by: Clément Léger <cleger@rivosinc.com>
> ---
> arch/riscv/include/asm/kvm_host.h | 1 -
> arch/riscv/include/asm/kvm_vcpu_sbi.h | 2 ++
> arch/riscv/kvm/vcpu.c | 2 +-
> arch/riscv/kvm/vcpu_sbi.c | 24 ++++++++++++++++++++++++
> arch/riscv/kvm/vcpu_sbi_sta.c | 3 ++-
> 5 files changed, 29 insertions(+), 3 deletions(-)
>
> diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
> index cc33e35cd628..bb93d2995ea2 100644
> --- a/arch/riscv/include/asm/kvm_host.h
> +++ b/arch/riscv/include/asm/kvm_host.h
> @@ -409,7 +409,6 @@ void __kvm_riscv_vcpu_power_on(struct kvm_vcpu *vcpu);
> void kvm_riscv_vcpu_power_on(struct kvm_vcpu *vcpu);
> bool kvm_riscv_vcpu_stopped(struct kvm_vcpu *vcpu);
>
> -void kvm_riscv_vcpu_sbi_sta_reset(struct kvm_vcpu *vcpu);
> void kvm_riscv_vcpu_record_steal_time(struct kvm_vcpu *vcpu);
>
> #endif /* __RISCV_KVM_HOST_H__ */
> diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h
> index bcb90757b149..cb68b3a57c8f 100644
> --- a/arch/riscv/include/asm/kvm_vcpu_sbi.h
> +++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h
> @@ -57,6 +57,7 @@ struct kvm_vcpu_sbi_extension {
> */
> int (*init)(struct kvm_vcpu *vcpu);
> void (*deinit)(struct kvm_vcpu *vcpu);
> + void (*reset)(struct kvm_vcpu *vcpu);
> };
>
> void kvm_riscv_vcpu_sbi_forward(struct kvm_vcpu *vcpu, struct kvm_run *run);
> @@ -78,6 +79,7 @@ bool riscv_vcpu_supports_sbi_ext(struct kvm_vcpu *vcpu, int idx);
> int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu, struct kvm_run *run);
> void kvm_riscv_vcpu_sbi_init(struct kvm_vcpu *vcpu);
> void kvm_riscv_vcpu_sbi_deinit(struct kvm_vcpu *vcpu);
> +void kvm_riscv_vcpu_sbi_reset(struct kvm_vcpu *vcpu);
>
> int kvm_riscv_vcpu_get_reg_sbi_sta(struct kvm_vcpu *vcpu, unsigned long reg_num,
> unsigned long *reg_val);
> diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> index 877bcc85c067..542747e2c7f5 100644
> --- a/arch/riscv/kvm/vcpu.c
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -94,7 +94,7 @@ static void kvm_riscv_reset_vcpu(struct kvm_vcpu *vcpu)
> vcpu->arch.hfence_tail = 0;
> memset(vcpu->arch.hfence_queue, 0, sizeof(vcpu->arch.hfence_queue));
>
> - kvm_riscv_vcpu_sbi_sta_reset(vcpu);
> + kvm_riscv_vcpu_sbi_reset(vcpu);
>
> /* Reset the guest CSRs for hotplug usecase */
> if (loaded)
> diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c
> index 858ddefd7e7f..18726096ef44 100644
> --- a/arch/riscv/kvm/vcpu_sbi.c
> +++ b/arch/riscv/kvm/vcpu_sbi.c
> @@ -539,3 +539,27 @@ void kvm_riscv_vcpu_sbi_deinit(struct kvm_vcpu *vcpu)
> ext->deinit(vcpu);
> }
> }
> +
> +void kvm_riscv_vcpu_sbi_reset(struct kvm_vcpu *vcpu)
> +{
> + struct kvm_vcpu_sbi_context *scontext = &vcpu->arch.sbi_context;
> + const struct kvm_riscv_sbi_extension_entry *entry;
> + const struct kvm_vcpu_sbi_extension *ext;
> + int idx, i;
> +
> + for (i = 0; i < ARRAY_SIZE(sbi_ext); i++) {
> + entry = &sbi_ext[i];
> + ext = entry->ext_ptr;
> + idx = entry->ext_idx;
> +
> + if (idx < 0 || idx >= ARRAY_SIZE(scontext->ext_status))
> + continue;
> +
> + if (scontext->ext_status[idx] != KVM_RISCV_SBI_EXT_STATUS_ENABLED ||
> + !ext->reset)
> + continue;
> +
> + ext->reset(vcpu);
> + }
> +}
> +
> diff --git a/arch/riscv/kvm/vcpu_sbi_sta.c b/arch/riscv/kvm/vcpu_sbi_sta.c
> index 5f35427114c1..cc6cb7c8f0e4 100644
> --- a/arch/riscv/kvm/vcpu_sbi_sta.c
> +++ b/arch/riscv/kvm/vcpu_sbi_sta.c
> @@ -16,7 +16,7 @@
> #include <asm/sbi.h>
> #include <asm/uaccess.h>
>
> -void kvm_riscv_vcpu_sbi_sta_reset(struct kvm_vcpu *vcpu)
> +static void kvm_riscv_vcpu_sbi_sta_reset(struct kvm_vcpu *vcpu)
> {
> vcpu->arch.sta.shmem = INVALID_GPA;
> vcpu->arch.sta.last_steal = 0;
> @@ -156,6 +156,7 @@ const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_sta = {
> .extid_end = SBI_EXT_STA,
> .handler = kvm_sbi_ext_sta_handler,
> .probe = kvm_sbi_ext_sta_probe,
> + .reset = kvm_riscv_vcpu_sbi_sta_reset,
> };
>
> int kvm_riscv_vcpu_get_reg_sbi_sta(struct kvm_vcpu *vcpu,
> --
> 2.47.2
>

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>