linux-kernel - [RFC PATCH 32/34] gunyah: Add hypercalls for sending doorbell

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Message-Id: <20250424141341.841734-33-karim.manaouil@linaro.org>
Date: Thu, 24 Apr 2025 15:13:39 +0100
From: Karim Manaouil <karim.manaouil@...aro.org>
To: linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org,
	linux-arm-msm@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	kvmarm@...ts.linux.dev
Cc: Karim Manaouil <karim.manaouil@...aro.org>,
	Alexander Graf <graf@...zon.com>,
	Alex Elder <elder@...nel.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Fuad Tabba <tabba@...gle.com>,
	Joey Gouly <joey.gouly@....com>,
	Jonathan Corbet <corbet@....net>,
	Marc Zyngier <maz@...nel.org>,
	Mark Brown <broonie@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Oliver Upton <oliver.upton@...ux.dev>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Prakruthi Deepak Heragu <quic_pheragu@...cinc.com>,
	Quentin Perret <qperret@...gle.com>,
	Rob Herring <robh@...nel.org>,
	Srinivas Kandagatla <srini@...nel.org>,
	Srivatsa Vaddagiri <quic_svaddagi@...cinc.com>,
	Will Deacon <will@...nel.org>,
	Haripranesh S <haripran@....qualcomm.com>,
	Carl van Schaik <cvanscha@....qualcomm.com>,
	Murali Nalajala <mnalajal@...cinc.com>,
	Sreenivasulu Chalamcharla <sreeniva@....qualcomm.com>,
	Trilok Soni <tsoni@...cinc.com>,
	Stefan Schmidt <stefan.schmidt@...aro.org>,
	Elliot Berman <quic_eberman@...cinc.com>,
	Alex Elder <elder@...aro.org>
Subject: [RFC PATCH 32/34] gunyah: Add hypercalls for sending doorbell

From: Elliot Berman <quic_eberman@...cinc.com>

Gunyah doorbells allow a virtual machine to signal another using
interrupts. Add the hypercalls needed to assert the interrupt.

Reviewed-by: Alex Elder <elder@...aro.org>
Signed-off-by: Elliot Berman <quic_eberman@...cinc.com>
Signed-off-by: Karim Manaouil <karim.manaouil@...aro.org>
---
 arch/arm64/gunyah/gunyah_hypercall.c | 38 ++++++++++++++++++++++++++++
 include/linux/gunyah.h               |  5 ++++
 2 files changed, 43 insertions(+)

diff --git a/arch/arm64/gunyah/gunyah_hypercall.c b/arch/arm64/gunyah/gunyah_hypercall.c
index 38403dc28c66..3c2672d683ae 100644
--- a/arch/arm64/gunyah/gunyah_hypercall.c
+++ b/arch/arm64/gunyah/gunyah_hypercall.c
@@ -37,6 +37,8 @@ EXPORT_SYMBOL_GPL(arch_is_gunyah_guest);
 
 /* clang-format off */
 #define GUNYAH_HYPERCALL_HYP_IDENTIFY		GUNYAH_HYPERCALL(0x8000)
+#define GUNYAH_HYPERCALL_BELL_SEND		GUNYAH_HYPERCALL(0x8012)
+#define GUNYAH_HYPERCALL_BELL_SET_MASK		GUNYAH_HYPERCALL(0x8015)
 #define GUNYAH_HYPERCALL_MSGQ_SEND		GUNYAH_HYPERCALL(0x801B)
 #define GUNYAH_HYPERCALL_MSGQ_RECV		GUNYAH_HYPERCALL(0x801C)
 #define GUNYAH_HYPERCALL_ADDRSPACE_MAP		GUNYAH_HYPERCALL(0x802B)
@@ -64,6 +66,42 @@ void gunyah_hypercall_hyp_identify(
 }
 EXPORT_SYMBOL_GPL(gunyah_hypercall_hyp_identify);
 
+/**
+ * gunyah_hypercall_bell_send() - Assert a gunyah doorbell
+ * @capid: capability ID of the doorbell
+ * @new_flags: bits to set on the doorbell
+ * @old_flags: Filled with the bits set before the send call if return value is GUNYAH_ERROR_OK
+ */
+enum gunyah_error gunyah_hypercall_bell_send(u64 capid, u64 new_flags, u64 *old_flags)
+{
+	struct arm_smccc_res res;
+
+	arm_smccc_1_1_hvc(GUNYAH_HYPERCALL_BELL_SEND, capid, new_flags, 0, &res);
+
+	if (res.a0 == GUNYAH_ERROR_OK && old_flags)
+		*old_flags = res.a1;
+
+	return res.a0;
+}
+EXPORT_SYMBOL_GPL(gunyah_hypercall_bell_send);
+
+/**
+ * gunyah_hypercall_bell_set_mask() - Set masks on a Gunyah doorbell
+ * @capid: capability ID of the doorbell
+ * @enable_mask: which bits trigger the receiver interrupt
+ * @ack_mask: which bits are automatically acknowledged when the receiver
+ *            interrupt is ack'd
+ */
+enum gunyah_error gunyah_hypercall_bell_set_mask(u64 capid, u64 enable_mask, u64 ack_mask)
+{
+	struct arm_smccc_res res;
+
+	arm_smccc_1_1_hvc(GUNYAH_HYPERCALL_BELL_SET_MASK, capid, enable_mask, ack_mask, 0, &res);
+
+	return res.a0;
+}
+EXPORT_SYMBOL_GPL(gunyah_hypercall_bell_set_mask);
+
 /**
  * gunyah_hypercall_msgq_send() - Send a buffer on a message queue
  * @capid: capability ID of the message queue to add message
diff --git a/include/linux/gunyah.h b/include/linux/gunyah.h
index 72aafc813664..26fdfa3174da 100644
--- a/include/linux/gunyah.h
+++ b/include/linux/gunyah.h
@@ -329,6 +329,11 @@ gunyah_api_version(const struct gunyah_hypercall_hyp_identify_resp *gunyah_api)
 void gunyah_hypercall_hyp_identify(
 	struct gunyah_hypercall_hyp_identify_resp *hyp_identity);
 
+enum gunyah_error gunyah_hypercall_bell_send(u64 capid, u64 new_flags,
+					     u64 *old_flags);
+enum gunyah_error gunyah_hypercall_bell_set_mask(u64 capid, u64 enable_mask,
+						 u64 ack_mask);
+
 /* Immediately raise RX vIRQ on receiver VM */
 #define GUNYAH_HYPERCALL_MSGQ_TX_FLAGS_PUSH BIT(0)
 
-- 
2.39.5