[PATCH 10/22] arm/arm64: Provide a wrapper for SMCCC 1.1 calls

From: Marc Zyngier <maz@kernel.org>
To: "Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Andrew Jones <drjones@redhat.com>,
	kvm@vger.kernel.org, Eric Auger <eric.auger@redhat.com>,
	Heinrich Schuchardt <xypron.glpk@gmx.de>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Christoffer Dall <christoffer.dall@arm.com>,
	Steven Price <steven.price@arm.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Julien Grall <julien.grall@arm.com>,
	Alexander Graf <graf@amazon.com>,
	linux-arm-kernel@lists.infradead.org,
	Zenghui Yu <yuzenghui@huawei.com>,
	James Morse <james.morse@arm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Will Deacon <will@kernel.org>,
	kvmarm@lists.cs.columbia.edu,
	Julien Thierry <julien.thierry.kdev@gmail.com>
Subject: [PATCH 10/22] arm/arm64: Provide a wrapper for SMCCC 1.1 calls
Date: Wed, 20 Nov 2019 16:42:24 +0000	[thread overview]
Message-ID: <20191120164236.29359-11-maz@kernel.org> (raw)
In-Reply-To: <20191120164236.29359-1-maz@kernel.org>

From: Steven Price <steven.price@arm.com>

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 conduit is configured/available 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>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 include/linux/arm-smccc.h | 45 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index 92e0046ce7a7..59494df0f55b 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -319,6 +319,51 @@ 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 SMCCC conduit is not defined. The empty asm statement
+ * avoids compiler warnings about unused variables.
+ */
+#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 SMCCC 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 = arm_smccc_1_1_get_conduit();		\
+		switch (method) {					\
+		case SMCCC_CONDUIT_HVC:					\
+			arm_smccc_1_1_hvc(__VA_ARGS__);			\
+			break;						\
+		case SMCCC_CONDUIT_SMC:					\
+			arm_smccc_1_1_smc(__VA_ARGS__);			\
+			break;						\
+		default:						\
+			__fail_smccc_1_1(__VA_ARGS__);			\
+			method = SMCCC_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,			\
-- 
2.20.1


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