[PATCH v7 3/4] RISC-V: KVM: Add Svade and Svadu Extensions Support for Guest/VM

[Samuel Holland]

Hi Yong-Xuan,

On 2024-07-12 3:38 AM, Yong-Xuan Wang wrote:
> We extend the KVM ISA extension ONE_REG interface to allow VMM tools to
> detect and enable Svade and Svadu extensions for Guest/VM. Since the
> henvcfg.ADUE is read-only zero if the menvcfg.ADUE is zero, the Svadu
> extension is available for Guest/VM and the Svade extension is allowed
> to disabledonly when arch_has_hw_pte_young() is true.
> 
> Signed-off-by: Yong-Xuan Wang <yongxuan.wang at sifive.com>
> Reviewed-by: Andrew Jones <ajones at ventanamicro.com>
> ---
>  arch/riscv/include/uapi/asm/kvm.h |  2 ++
>  arch/riscv/kvm/vcpu.c             |  3 +++
>  arch/riscv/kvm/vcpu_onereg.c      | 15 +++++++++++++++
>  3 files changed, 20 insertions(+)
> 
> diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
> index e878e7cc3978..a5e0c35d7e9a 100644
> --- a/arch/riscv/include/uapi/asm/kvm.h
> +++ b/arch/riscv/include/uapi/asm/kvm.h
> @@ -168,6 +168,8 @@ enum KVM_RISCV_ISA_EXT_ID {
>  	KVM_RISCV_ISA_EXT_ZTSO,
>  	KVM_RISCV_ISA_EXT_ZACAS,
>  	KVM_RISCV_ISA_EXT_SSCOFPMF,
> +	KVM_RISCV_ISA_EXT_SVADE,
> +	KVM_RISCV_ISA_EXT_SVADU,
>  	KVM_RISCV_ISA_EXT_MAX,
>  };
>  
> diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> index 17e21df36cc1..64a15af459e0 100644
> --- a/arch/riscv/kvm/vcpu.c
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -540,6 +540,9 @@ static void kvm_riscv_vcpu_setup_config(struct kvm_vcpu *vcpu)
>  	if (riscv_isa_extension_available(isa, ZICBOZ))
>  		cfg->henvcfg |= ENVCFG_CBZE;
>  
> +	if (riscv_isa_extension_available(isa, SVADU))
> +		cfg->henvcfg |= ENVCFG_ADUE;

This is correct for now because patch 1 ensures the host (and therefore also the
guest) never has both Svade and Svadu available. When that changes, this check
will need to add an "&& !riscv_isa_extension_available(isa, SVADE)" condition so
it matches the behavior described in the DT binding. There's no need to resend
to make this addition, but if you do, it wouldn't hurt to include it so it's not
forgotten later. (It looks maybe like v6 only partially implemented Andrew's
suggestion?)

Reviewed-by: Samuel Holland <samuel.holland at sifive.com>

> +
>  	if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SMSTATEEN)) {
>  		cfg->hstateen0 |= SMSTATEEN0_HSENVCFG;
>  		if (riscv_isa_extension_available(isa, SSAIA))
> diff --git a/arch/riscv/kvm/vcpu_onereg.c b/arch/riscv/kvm/vcpu_onereg.c
> index 62874fbca29f..474fdeafe9fe 100644
> --- a/arch/riscv/kvm/vcpu_onereg.c
> +++ b/arch/riscv/kvm/vcpu_onereg.c
> @@ -15,6 +15,7 @@
>  #include <asm/cacheflush.h>
>  #include <asm/cpufeature.h>
>  #include <asm/kvm_vcpu_vector.h>
> +#include <asm/pgtable.h>
>  #include <asm/vector.h>
>  
>  #define KVM_RISCV_BASE_ISA_MASK		GENMASK(25, 0)
> @@ -38,6 +39,8 @@ static const unsigned long kvm_isa_ext_arr[] = {
>  	KVM_ISA_EXT_ARR(SSAIA),
>  	KVM_ISA_EXT_ARR(SSCOFPMF),
>  	KVM_ISA_EXT_ARR(SSTC),
> +	KVM_ISA_EXT_ARR(SVADE),
> +	KVM_ISA_EXT_ARR(SVADU),
>  	KVM_ISA_EXT_ARR(SVINVAL),
>  	KVM_ISA_EXT_ARR(SVNAPOT),
>  	KVM_ISA_EXT_ARR(SVPBMT),
> @@ -105,6 +108,12 @@ static bool kvm_riscv_vcpu_isa_enable_allowed(unsigned long ext)
>  		return __riscv_isa_extension_available(NULL, RISCV_ISA_EXT_SSAIA);
>  	case KVM_RISCV_ISA_EXT_V:
>  		return riscv_v_vstate_ctrl_user_allowed();
> +	case KVM_RISCV_ISA_EXT_SVADU:
> +		/*
> +		 * The henvcfg.ADUE is read-only zero if menvcfg.ADUE is zero.
> +		 * Guest OS can use Svadu only when host os enable Svadu.
> +		 */
> +		return arch_has_hw_pte_young();
>  	default:
>  		break;
>  	}
> @@ -167,6 +176,12 @@ static bool kvm_riscv_vcpu_isa_disable_allowed(unsigned long ext)
>  	/* Extensions which can be disabled using Smstateen */
>  	case KVM_RISCV_ISA_EXT_SSAIA:
>  		return riscv_has_extension_unlikely(RISCV_ISA_EXT_SMSTATEEN);
> +	case KVM_RISCV_ISA_EXT_SVADE:
> +		/*
> +		 * The henvcfg.ADUE is read-only zero if menvcfg.ADUE is zero.
> +		 * Svade is not allowed to disable when the platform use Svade.
> +		 */
> +		return arch_has_hw_pte_young();
>  	default:
>  		break;
>  	}