Re: [RFC PATCH v3 2/5] KVM: arm64: Add support for PSCI v1.2 and v1.3

From: Marc Zyngier
Date: Fri Mar 22 2024 - 12:05:18 EST


On Tue, 19 Mar 2024 12:59:03 +0000,
David Woodhouse <dwmw2@xxxxxxxxxxxxx> wrote:
>
> From: David Woodhouse <dwmw@xxxxxxxxxxxx>
>
> Since the v1.3 specification is still in Alpha, only default to v1.2
> unless userspace explicitly requests v1.3 for now.
>
> Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
> ---
> arch/arm64/kvm/hypercalls.c | 2 ++
> arch/arm64/kvm/psci.c | 6 +++++-
> include/kvm/arm_psci.h | 4 +++-
> 3 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
> index 5763d979d8ca..9c6267ca2b82 100644
> --- a/arch/arm64/kvm/hypercalls.c
> +++ b/arch/arm64/kvm/hypercalls.c
> @@ -575,6 +575,8 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
> case KVM_ARM_PSCI_0_2:
> case KVM_ARM_PSCI_1_0:
> case KVM_ARM_PSCI_1_1:
> + case KVM_ARM_PSCI_1_2:
> + case KVM_ARM_PSCI_1_3:
> if (!wants_02)
> return -EINVAL;
> vcpu->kvm->arch.psci_version = val;
> diff --git a/arch/arm64/kvm/psci.c b/arch/arm64/kvm/psci.c
> index 1f69b667332b..f689ef3f2f10 100644
> --- a/arch/arm64/kvm/psci.c
> +++ b/arch/arm64/kvm/psci.c
> @@ -322,7 +322,7 @@ static int kvm_psci_1_x_call(struct kvm_vcpu *vcpu, u32 minor)
>
> switch(psci_fn) {
> case PSCI_0_2_FN_PSCI_VERSION:
> - val = minor == 0 ? KVM_ARM_PSCI_1_0 : KVM_ARM_PSCI_1_1;
> + val = PSCI_VERSION(1, minor);
> break;
> case PSCI_1_0_FN_PSCI_FEATURES:
> arg = smccc_get_arg1(vcpu);
> @@ -449,6 +449,10 @@ int kvm_psci_call(struct kvm_vcpu *vcpu)
> }
>
> switch (version) {
> + case KVM_ARM_PSCI_1_3:
> + return kvm_psci_1_x_call(vcpu, 3);
> + case KVM_ARM_PSCI_1_2:
> + return kvm_psci_1_x_call(vcpu, 2);
> case KVM_ARM_PSCI_1_1:
> return kvm_psci_1_x_call(vcpu, 1);
> case KVM_ARM_PSCI_1_0:
> diff --git a/include/kvm/arm_psci.h b/include/kvm/arm_psci.h
> index e8fb624013d1..ebd7d9a12790 100644
> --- a/include/kvm/arm_psci.h
> +++ b/include/kvm/arm_psci.h
> @@ -14,8 +14,10 @@
> #define KVM_ARM_PSCI_0_2 PSCI_VERSION(0, 2)
> #define KVM_ARM_PSCI_1_0 PSCI_VERSION(1, 0)
> #define KVM_ARM_PSCI_1_1 PSCI_VERSION(1, 1)
> +#define KVM_ARM_PSCI_1_2 PSCI_VERSION(1, 2)
> +#define KVM_ARM_PSCI_1_3 PSCI_VERSION(1, 3)
>
> -#define KVM_ARM_PSCI_LATEST KVM_ARM_PSCI_1_1
> +#define KVM_ARM_PSCI_LATEST KVM_ARM_PSCI_1_2 /* v1.3 is still Alpha */
>
> static inline int kvm_psci_version(struct kvm_vcpu *vcpu)
> {

Consider making the visibility of v1.2/1.3 to userspace and guest the
last patch in the series, so that there is no transient support for
some oddball PSCI version with no feature (keeps bisection clean).

Thanks,

M.

--
Without deviation from the norm, progress is not possible.