Re: [PATCH v3 16/23] kvm: arm64: Forward safe PSCI SMCs coming from host

Sudeep Holla
2020-11-27T16:52:16Z

On Thu, Nov 26, 2020 at 03:54:14PM +0000, David Brazdil wrote:
> Forward the following PSCI SMCs issued by host to EL3 as they do not
> require the hypervisor's intervention. This assumes that EL3 correctly
> implements the PSCI specification.
>
> Only function IDs implemented in Linux are included.
>
> Where both 32-bit and 64-bit variants exist, it is assumed that the host
> will always use the 64-bit variant.
>
> * SMCs that only return information about the system
> * PSCI_VERSION - PSCI version implemented by EL3
> * PSCI_FEATURES - optional features supported by EL3
> * AFFINITY_INFO - power state of core/cluster
> * MIGRATE_INFO_TYPE - whether Trusted OS can be migrated
> * MIGRATE_INFO_UP_CPU - resident core of Trusted OS
> * operations which do not affect the hypervisor
> * MIGRATE - migrate Trusted OS to a different core
> * SET_SUSPEND_MODE - toggle OS-initiated mode
> * system shutdown/reset
> * SYSTEM_OFF
> * SYSTEM_RESET
> * SYSTEM_RESET2
>
> Signed-off-by: David Brazdil <dbrazdil@google.com>
> ---
> arch/arm64/kvm/hyp/nvhe/psci-relay.c | 43 +++++++++++++++++++++++++++-
> 1 file changed, 42 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/hyp/nvhe/psci-relay.c b/arch/arm64/kvm/hyp/nvhe/psci-relay.c
> index e7091d89f0fc..7aa87ab7f5ce 100644
> --- a/arch/arm64/kvm/hyp/nvhe/psci-relay.c
> +++ b/arch/arm64/kvm/hyp/nvhe/psci-relay.c
> @@ -57,14 +57,51 @@ static bool is_psci_call(u64 func_id)
> }
> }
>
> +static unsigned long psci_call(unsigned long fn, unsigned long arg0,
> + unsigned long arg1, unsigned long arg2)
> +{
> + struct arm_smccc_res res;
> +
> + arm_smccc_1_1_smc(fn, arg0, arg1, arg2, &res);
> + return res.a0;
> +}
> +
> +static unsigned long psci_forward(struct kvm_cpu_context *host_ctxt)
> +{
> + return psci_call(cpu_reg(host_ctxt, 0), cpu_reg(host_ctxt, 1),
> + cpu_reg(host_ctxt, 2), cpu_reg(host_ctxt, 3));
> +}
> +
> +static __noreturn unsigned long psci_forward_noreturn(struct kvm_cpu_context *host_ctxt)
> +{
> + psci_forward(host_ctxt);
> + hyp_panic(); /* unreachable */
> +}
> +
> static unsigned long psci_0_1_handler(u64 func_id, struct kvm_cpu_context *host_ctxt)
> {
> - return PSCI_RET_NOT_SUPPORTED;
> + if (func_id == kvm_host_psci_function_id[PSCI_FN_CPU_OFF])
> + return psci_forward(host_ctxt);
> + else if (func_id == kvm_host_psci_function_id[PSCI_FN_MIGRATE])
> + return psci_forward(host_ctxt);

Looks weird or I am not seeing something right ? Same action for both
right ? Can't they be combined ?

--
Regards,
Sudeep