Re: [PATCH v11 06/26] virt: gunyah: msgq: Add hypercalls to send and receive messages

From: Alex Elder <elder@linaro.org>
To: Elliot Berman <quic_eberman@quicinc.com>,
	Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
	Prakruthi Deepak Heragu <quic_pheragu@quicinc.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>
Cc: Murali Nalajala <quic_mnalajal@quicinc.com>,
	Trilok Soni <quic_tsoni@quicinc.com>,
	Srivatsa Vaddagiri <quic_svaddagi@quicinc.com>,
	Carl van Schaik <quic_cvanscha@quicinc.com>,
	Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
	Bjorn Andersson <andersson@kernel.org>,
	Konrad Dybcio <konrad.dybcio@linaro.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Jonathan Corbet <corbet@lwn.net>,
	Bagas Sanjaya <bagasdotme@gmail.com>,
	Andy Gross <agross@kernel.org>,
	Jassi Brar <jassisinghbrar@gmail.com>,
	linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v11 06/26] virt: gunyah: msgq: Add hypercalls to send and receive messages
Date: Fri, 31 Mar 2023 09:25:02 -0500	[thread overview]
Message-ID: <947e17c0-c157-148c-035b-f9578466a6e1@linaro.org> (raw)
In-Reply-To: <20230304010632.2127470-7-quic_eberman@quicinc.com>

On 3/3/23 7:06 PM, Elliot Berman wrote:
> Add hypercalls to send and receive messages on a Gunyah message queue.
> 
> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>

One comment below.	-Alex

> ---
>   arch/arm64/gunyah/gunyah_hypercall.c | 31 ++++++++++++++++++++++++++++
>   include/linux/gunyah.h               |  6 ++++++
>   2 files changed, 37 insertions(+)
> 
> diff --git a/arch/arm64/gunyah/gunyah_hypercall.c b/arch/arm64/gunyah/gunyah_hypercall.c
> index 0d14e767e2c8..3420d8f286a9 100644
> --- a/arch/arm64/gunyah/gunyah_hypercall.c
> +++ b/arch/arm64/gunyah/gunyah_hypercall.c
> @@ -41,6 +41,8 @@ EXPORT_SYMBOL_GPL(arch_is_gh_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
> @@ -60,5 +62,34 @@ 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, void *buff, int tx_flags, bool *ready)

The tx_flags argument--being a mask of some kind--should be unsigned,
and perhaps 64 bits wide.  The only caller passes a u64 value here
(which would technically be truncated).

> +{
> +	struct arm_smccc_res res;
> +
> +	arm_smccc_1_1_hvc(GH_HYPERCALL_MSGQ_SEND, capid, size, (uintptr_t)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, void *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, (uintptr_t)buff, size, 0, &res);
> +
> +	if (res.a0 == GH_ERROR_OK) {
> +		*recv_size = res.a1;
> +		*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 bd080e3a6fc9..18cfbf5ee48b 100644
> --- a/include/linux/gunyah.h
> +++ b/include/linux/gunyah.h
> @@ -108,4 +108,10 @@ 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, void *buff, int tx_flags, bool *ready);
> +enum gh_error gh_hypercall_msgq_recv(u64 capid, void *buff, size_t size, size_t *recv_size,
> +					bool *ready);
> +
>   #endif