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From: Elliot Berman <quic_eberman@quicinc.com>
Date: Thu, 22 Feb 2024 15:16:37 -0800
Subject: [PATCH v17 14/35] virt: gunyah: Add hypercalls for running a vCPU
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Message-ID: <20240222-gunyah-v17-14-1e9da6763d38@quicinc.com>
References: <20240222-gunyah-v17-0-1e9da6763d38@quicinc.com>
In-Reply-To: <20240222-gunyah-v17-0-1e9da6763d38@quicinc.com>
To: Alex Elder <elder@linaro.org>,
        Srinivas Kandagatla
	<srinivas.kandagatla@linaro.org>,
        Murali Nalajal <quic_mnalajal@quicinc.com>,
        Trilok Soni <quic_tsoni@quicinc.com>,
        Srivatsa Vaddagiri
	<quic_svaddagi@quicinc.com>,
        Carl van Schaik <quic_cvanscha@quicinc.com>,
        Philip Derrin <quic_pderrin@quicinc.com>,
        Prakruthi Deepak Heragu
	<quic_pheragu@quicinc.com>,
        Jonathan Corbet <corbet@lwn.net>, Rob Herring
	<robh+dt@kernel.org>,
        Krzysztof Kozlowski
	<krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Konrad Dybcio <konrad.dybcio@linaro.org>,
        Bjorn Andersson
	<andersson@kernel.org>,
        Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
        "Fuad
 Tabba" <tabba@google.com>,
        Sean Christopherson <seanjc@google.com>,
        "Andrew
 Morton" <akpm@linux-foundation.org>
CC: <linux-arm-msm@vger.kernel.org>, <linux-doc@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <devicetree@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>, <linux-mm@kvack.org>,
        Elliot Berman
	<quic_eberman@quicinc.com>

Add hypercall to donate CPU time to a vCPU.

Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
---
 arch/arm64/gunyah/gunyah_hypercall.c | 37 ++++++++++++++++++++++++++++++++++++
 include/linux/gunyah.h               | 35 ++++++++++++++++++++++++++++++++++
 2 files changed, 72 insertions(+)

diff --git a/arch/arm64/gunyah/gunyah_hypercall.c b/arch/arm64/gunyah/gunyah_hypercall.c
index 1302e128be6e9..fee21df42c176 100644
--- a/arch/arm64/gunyah/gunyah_hypercall.c
+++ b/arch/arm64/gunyah/gunyah_hypercall.c
@@ -39,6 +39,7 @@ EXPORT_SYMBOL_GPL(arch_is_gunyah_guest);
 #define GUNYAH_HYPERCALL_HYP_IDENTIFY		GUNYAH_HYPERCALL(0x8000)
 #define GUNYAH_HYPERCALL_MSGQ_SEND		GUNYAH_HYPERCALL(0x801B)
 #define GUNYAH_HYPERCALL_MSGQ_RECV		GUNYAH_HYPERCALL(0x801C)
+#define GUNYAH_HYPERCALL_VCPU_RUN		GUNYAH_HYPERCALL(0x8065)
 /* clang-format on */
 
 /**
@@ -113,5 +114,41 @@ enum gunyah_error gunyah_hypercall_msgq_recv(u64 capid, void *buff, size_t size,
 }
 EXPORT_SYMBOL_GPL(gunyah_hypercall_msgq_recv);
 
+/**
+ * gunyah_hypercall_vcpu_run() - Donate CPU time to a vcpu
+ * @capid: capability ID of the vCPU to run
+ * @resume_data: Array of 3 state-specific resume data
+ * @resp: Filled reason why vCPU exited when return value is GUNYAH_ERROR_OK
+ *
+ * See also:
+ * https://github.com/quic/gunyah-hypervisor/blob/develop/docs/api/gunyah_api.md#run-a-proxy-scheduled-vcpu-thread
+ */
+enum gunyah_error
+gunyah_hypercall_vcpu_run(u64 capid, unsigned long *resume_data,
+			  struct gunyah_hypercall_vcpu_run_resp *resp)
+{
+	struct arm_smccc_1_2_regs args = {
+		.a0 = GUNYAH_HYPERCALL_VCPU_RUN,
+		.a1 = capid,
+		.a2 = resume_data[0],
+		.a3 = resume_data[1],
+		.a4 = resume_data[2],
+		/* C language says this will be implictly zero. Gunyah requires 0, so be explicit */
+		.a5 = 0,
+	};
+	struct arm_smccc_1_2_regs res;
+
+	arm_smccc_1_2_hvc(&args, &res);
+	if (res.a0 == GUNYAH_ERROR_OK) {
+		resp->sized_state = res.a1;
+		resp->state_data[0] = res.a2;
+		resp->state_data[1] = res.a3;
+		resp->state_data[2] = res.a4;
+	}
+
+	return res.a0;
+}
+EXPORT_SYMBOL_GPL(gunyah_hypercall_vcpu_run);
+
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("Gunyah Hypervisor Hypercalls");
diff --git a/include/linux/gunyah.h b/include/linux/gunyah.h
index 18ecebf41a3ff..6c24544f38dc9 100644
--- a/include/linux/gunyah.h
+++ b/include/linux/gunyah.h
@@ -273,4 +273,39 @@ enum gunyah_error gunyah_hypercall_msgq_send(u64 capid, size_t size, void *buff,
 enum gunyah_error gunyah_hypercall_msgq_recv(u64 capid, void *buff, size_t size,
 					     size_t *recv_size, bool *ready);
 
+struct gunyah_hypercall_vcpu_run_resp {
+	union {
+		enum {
+			/* clang-format off */
+			/* VCPU is ready to run */
+			GUNYAH_VCPU_STATE_READY			= 0,
+			/* VCPU is sleeping until an interrupt arrives */
+			GUNYAH_VCPU_STATE_EXPECTS_WAKEUP	= 1,
+			/* VCPU is powered off */
+			GUNYAH_VCPU_STATE_POWERED_OFF		= 2,
+			/* VCPU is blocked in EL2 for unspecified reason */
+			GUNYAH_VCPU_STATE_BLOCKED		= 3,
+			/* VCPU has returned for MMIO READ */
+			GUNYAH_VCPU_ADDRSPACE_VMMIO_READ	= 4,
+			/* VCPU has returned for MMIO WRITE */
+			GUNYAH_VCPU_ADDRSPACE_VMMIO_WRITE	= 5,
+			/* VCPU blocked on fault where we can demand page */
+			GUNYAH_VCPU_ADDRSPACE_PAGE_FAULT	= 7,
+			/* clang-format on */
+		} state;
+		u64 sized_state;
+	};
+	u64 state_data[3];
+};
+
+enum {
+	GUNYAH_ADDRSPACE_VMMIO_ACTION_EMULATE = 0,
+	GUNYAH_ADDRSPACE_VMMIO_ACTION_RETRY = 1,
+	GUNYAH_ADDRSPACE_VMMIO_ACTION_FAULT = 2,
+};
+
+enum gunyah_error
+gunyah_hypercall_vcpu_run(u64 capid, unsigned long *resume_data,
+			  struct gunyah_hypercall_vcpu_run_resp *resp);
+
 #endif

-- 
2.34.1