Re: [PATCH v10 06/26] virt: gunyah: msgq: Add hypercalls to send and receive messages

[Alex Elder]

On 2/14/23 3:23 PM, Elliot Berman wrote:
> Add hypercalls to send and receive messages on a Gunyah message queue.
>
> Signed-off-by: Elliot Berman <quic_eberman@xxxxxxxxxxx>
> ---
>   arch/arm64/gunyah/gunyah_hypercall.c | 32 ++++++++++++++++++++++++++++
>   include/linux/gunyah.h               |  7 ++++++
>   2 files changed, 39 insertions(+)
>
> diff --git a/arch/arm64/gunyah/gunyah_hypercall.c b/arch/arm64/gunyah/gunyah_hypercall.c
> index f30d06ee80cf..2ca9ab098ff6 100644
> --- a/arch/arm64/gunyah/gunyah_hypercall.c
> +++ b/arch/arm64/gunyah/gunyah_hypercall.c
> @@ -38,6 +38,8 @@ EXPORT_SYMBOL_GPL(arch_is_gunyah_guest);
>   						   fn)
>   
>   #define GH_HYPERCALL_HYP_IDENTIFY		GH_HYPERCALL(0x8000)
> +#define GH_HYPERCALL_MSGQ_SEND			GH_HYPERCALL(0x801B)
> +#define GH_HYPERCALL_MSGQ_RECV			GH_HYPERCALL(0x801C)
>   
>   /**
>    * gh_hypercall_hyp_identify() - Returns build information and feature flags
> @@ -57,5 +59,35 @@ void gh_hypercall_hyp_identify(struct gh_hypercall_hyp_identify_resp *hyp_identi
>   }
>   EXPORT_SYMBOL_GPL(gh_hypercall_hyp_identify);
>   
> +enum gh_error gh_hypercall_msgq_send(u64 capid, size_t size, uintptr_t buff, int tx_flags,
> +					bool *ready)
> +{
> +	struct arm_smccc_res res;
> +
> +	arm_smccc_1_1_hvc(GH_HYPERCALL_MSGQ_SEND, capid, size, buff, tx_flags, 0, &res);
> +
> +	if (res.a0 == GH_ERROR_OK)
> +		*ready = res.a1;
> +
> +	return res.a0;
> +}
> +EXPORT_SYMBOL_GPL(gh_hypercall_msgq_send);
> +
> +enum gh_error gh_hypercall_msgq_recv(u64 capid, uintptr_t buff, size_t size, size_t *recv_size,
> +					bool *ready)
> +{
> +	struct arm_smccc_res res;
> +
> +	arm_smccc_1_1_hvc(GH_HYPERCALL_MSGQ_RECV, capid, buff, size, 0, &res);
> +
> +	if (res.a0 == GH_ERROR_OK) {
> +		*recv_size = res.a1;

Is there any chance the 64-bit size is incompatible
with size_t?  (Too big?)

> +		*ready = res.a2;

		*ready = !!res.a2;

> +	}
> +
> +	return res.a0;
> +}
> +EXPORT_SYMBOL_GPL(gh_hypercall_msgq_recv);
> +
>   MODULE_LICENSE("GPL");
>   MODULE_DESCRIPTION("Gunyah Hypervisor Hypercalls");
> diff --git a/include/linux/gunyah.h b/include/linux/gunyah.h
> index 3fef2854c5e1..cb6df4eec5c2 100644
> --- a/include/linux/gunyah.h
> +++ b/include/linux/gunyah.h
> @@ -112,4 +112,11 @@ struct gh_hypercall_hyp_identify_resp {
>   
>   void gh_hypercall_hyp_identify(struct gh_hypercall_hyp_identify_resp *hyp_identity);
>   
> +#define GH_HYPERCALL_MSGQ_TX_FLAGS_PUSH		BIT(0)
> +
> +enum gh_error gh_hypercall_msgq_send(u64 capid, size_t size, uintptr_t buff, int tx_flags,
> +					bool *ready);

Why uintptr_t?  Why not just pass a host pointer (void *)
and do whatever conversion is necessary inside the function?

					-Alex

> +enum gh_error gh_hypercall_msgq_recv(u64 capid, uintptr_t buff, size_t size, size_t *recv_size,
> +					bool *ready);
> +
>   #endif