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From: Marc Zyngier <maz@kernel.org>
To: Steven Price <steven.price@arm.com>
Cc: kvm@vger.kernel.org, Catalin Marinas <catalin.marinas@arm.com>,
	linux-doc@vger.kernel.org, Russell King <linux@armlinux.org.uk>,
	linux-kernel@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
	Will Deacon <will@kernel.org>,
	kvmarm@lists.cs.columbia.edu,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v6 08/10] arm/arm64: Provide a wrapper for SMCCC 1.1 calls
Date: Mon, 21 Oct 2019 12:42:57 +0100
Message-ID: <099040bb979b7cb878a7f489033aacc7@www.loen.fr> (raw)
In-Reply-To: <20191011125930.40834-9-steven.price@arm.com>

On 2019-10-11 13:59, Steven Price wrote:
> SMCCC 1.1 calls may use either HVC or SMC depending on the PSCI
> conduit. Rather than coding this in every call site provide a macro
> which uses the correct instruction. The macro also handles the case
> where no PSCI conduit is configured returning a not supported error
> in res, along with returning the conduit used for the call.
>
> This allow us to remove some duplicated code and will be useful later
> when adding paravirtualized time hypervisor calls.
>
> Signed-off-by: Steven Price <steven.price@arm.com>
> Acked-by: Will Deacon <will@kernel.org>
> ---
>  include/linux/arm-smccc.h | 44 
> +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 44 insertions(+)
>
> diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
> index 5daf0e2adf47..fd84a9bfb455 100644
> --- a/include/linux/arm-smccc.h
> +++ b/include/linux/arm-smccc.h
> @@ -303,6 +303,50 @@ asmlinkage void __arm_smccc_hvc(unsigned long
> a0, unsigned long a1,
>  #define SMCCC_RET_NOT_SUPPORTED			-1
>  #define SMCCC_RET_NOT_REQUIRED			-2
>
> +/* Like arm_smccc_1_1* but always returns SMCCC_RET_NOT_SUPPORTED.
> + * Used when the PSCI conduit is not defined. The empty asm 
> statement
> + * avoids compiler warnings about unused variables.

nit: comment style.

> + */
> +#define __fail_smccc_1_1(...)						\
> +	do {								\
> +		__declare_args(__count_args(__VA_ARGS__), __VA_ARGS__);	\
> +		asm ("" __constraints(__count_args(__VA_ARGS__)));	\
> +		if (___res)						\
> +			___res->a0 = SMCCC_RET_NOT_SUPPORTED;		\
> +	} while (0)
> +
> +/*
> + * arm_smccc_1_1_invoke() - make an SMCCC v1.1 compliant call
> + *
> + * This is a variadic macro taking one to eight source arguments, 
> and
> + * an optional return structure.
> + *
> + * @a0-a7: arguments passed in registers 0 to 7
> + * @res: result values from registers 0 to 3
> + *
> + * This macro will make either an HVC call or an SMC call depending 
> on the
> + * current PSCI conduit. If no valid conduit is available then -1
> + * (SMCCC_RET_NOT_SUPPORTED) is returned in @res.a0 (if supplied).
> + *
> + * The return value also provides the conduit that was used.
> + */
> +#define arm_smccc_1_1_invoke(...) ({					\
> +		int method = psci_ops.conduit;				\
> +		switch (method) {					\
> +		case PSCI_CONDUIT_HVC:					\
> +			arm_smccc_1_1_hvc(__VA_ARGS__);			\
> +			break;						\
> +		case PSCI_CONDUIT_SMC:					\
> +			arm_smccc_1_1_smc(__VA_ARGS__);			\
> +			break;						\
> +		default:						\
> +			__fail_smccc_1_1(__VA_ARGS__);			\
> +			method = PSCI_CONDUIT_NONE;			\
> +			break;						\
> +		}							\
> +		method;							\
> +	})
> +
>  /* Paravirtualised time calls (defined by ARM DEN0057A) */
>  #define ARM_SMCCC_HV_PV_TIME_FEATURES				\
>  	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\

All this should most probably go on top of the SMCCC conduit cleanup 
that
has already been already queued in the arm64 tree (see 
arm64/for-next/smccc-conduit-cleanup).

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...
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  reply index

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-11 12:59 [PATCH v6 00/10] arm64: Stolen time support Steven Price
2019-10-11 12:59 ` [PATCH v6 01/10] KVM: arm64: Document PV-time interface Steven Price
2019-10-11 12:59 ` [PATCH v6 02/10] KVM: arm/arm64: Factor out hypercall handling from PSCI code Steven Price
2019-10-11 12:59 ` [PATCH v6 03/10] KVM: arm64: Implement PV_TIME_FEATURES call Steven Price
2019-10-11 12:59 ` [PATCH v6 04/10] KVM: Implement kvm_put_guest() Steven Price
2019-10-11 12:59 ` [PATCH v6 05/10] KVM: arm64: Support stolen time reporting via shared structure Steven Price
2019-10-19 11:12   ` Marc Zyngier
2019-10-21 10:21     ` Steven Price
2019-10-21 10:40       ` Marc Zyngier
2019-10-21 11:24         ` Steven Price
2019-10-11 12:59 ` [PATCH v6 06/10] KVM: Allow kvm_device_ops to be const Steven Price
2019-10-11 12:59 ` [PATCH v6 07/10] KVM: arm64: Provide VCPU attributes for stolen time Steven Price
2019-10-19 11:28   ` Marc Zyngier
2019-10-21 11:00     ` Steven Price
2019-10-11 12:59 ` [PATCH v6 08/10] arm/arm64: Provide a wrapper for SMCCC 1.1 calls Steven Price
2019-10-21 11:42   ` Marc Zyngier [this message]
2019-10-21 13:43     ` Steven Price
2019-10-21 14:05       ` Marc Zyngier
2019-10-11 12:59 ` [PATCH v6 09/10] arm/arm64: Make use of the SMCCC 1.1 wrapper Steven Price
2019-10-11 12:59 ` [PATCH v6 10/10] arm64: Retrieve stolen time as paravirtualized guest Steven Price
2019-10-19 20:28   ` Marc Zyngier
2019-10-21  5:01     ` Jürgen Groß
2019-10-21  7:55       ` Marc Zyngier
2019-10-21 12:14     ` Steven Price

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