linux-kernel - [PATCH v5 19/27] arm64: Add support for GICv5 GSB barriers

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Message-Id: <20250618-gicv5-host-v5-19-d9e622ac5539@kernel.org>
Date: Wed, 18 Jun 2025 12:17:34 +0200
From: Lorenzo Pieralisi <lpieralisi@...nel.org>
To: Marc Zyngier <maz@...nel.org>, Thomas Gleixner <tglx@...utronix.de>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>
Cc: Arnd Bergmann <arnd@...db.de>, 
 Sascha Bischoff <sascha.bischoff@....com>, 
 Jonathan Cameron <Jonathan.Cameron@...wei.com>, 
 Timothy Hayes <timothy.hayes@....com>, Bjorn Helgaas <bhelgaas@...gle.com>, 
 "Liam R. Howlett" <Liam.Howlett@...cle.com>, 
 Peter Maydell <peter.maydell@...aro.org>, 
 Mark Rutland <mark.rutland@....com>, Jiri Slaby <jirislaby@...nel.org>, 
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 devicetree@...r.kernel.org, linux-pci@...r.kernel.org, 
 Lorenzo Pieralisi <lpieralisi@...nel.org>
Subject: [PATCH v5 19/27] arm64: Add support for GICv5 GSB barriers

The GICv5 architecture introduces two barriers instructions
(GSB SYS, GSB ACK) that are used to manage interrupt effects.

Rework macro used to emit the SB barrier instruction and implement
the GSB barriers on top of it.

Suggested-by: Marc Zyngier <maz@...nel.org>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@...nel.org>
Cc: Will Deacon <will@...nel.org>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Marc Zyngier <maz@...nel.org>
---
 arch/arm64/include/asm/barrier.h |  3 +++
 arch/arm64/include/asm/sysreg.h  | 10 +++++++---
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h
index 1ca947d5c939..f5801b0ba9e9 100644
--- a/arch/arm64/include/asm/barrier.h
+++ b/arch/arm64/include/asm/barrier.h
@@ -44,6 +44,9 @@
 						 SB_BARRIER_INSN"nop\n",	\
 						 ARM64_HAS_SB))

+#define gsb_ack()	asm volatile(GSB_ACK_BARRIER_INSN : : : "memory")
+#define gsb_sys()	asm volatile(GSB_SYS_BARRIER_INSN : : : "memory")
+
 #ifdef CONFIG_ARM64_PSEUDO_NMI
 #define pmr_sync()						\
 	do {							\
diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index f1bb0d10c39a..9b5fc6389715 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -113,10 +113,14 @@
 /* Register-based PAN access, for save/restore purposes */
 #define SYS_PSTATE_PAN			sys_reg(3, 0, 4, 2, 3)

-#define __SYS_BARRIER_INSN(CRm, op2, Rt) \
-	__emit_inst(0xd5000000 | sys_insn(0, 3, 3, (CRm), (op2)) | ((Rt) & 0x1f))
+#define __SYS_BARRIER_INSN(op0, op1, CRn, CRm, op2, Rt)			\
+	__emit_inst(0xd5000000					|	\
+		    sys_insn((op0), (op1), (CRn), (CRm), (op2))	|	\
+		    ((Rt) & 0x1f))

-#define SB_BARRIER_INSN			__SYS_BARRIER_INSN(0, 7, 31)
+#define SB_BARRIER_INSN			__SYS_BARRIER_INSN(0, 3, 3, 0, 7, 31)
+#define GSB_SYS_BARRIER_INSN		__SYS_BARRIER_INSN(1, 0, 12, 0, 0, 31)
+#define GSB_ACK_BARRIER_INSN		__SYS_BARRIER_INSN(1, 0, 12, 0, 1, 31)

 /* Data cache zero operations */
 #define SYS_DC_ISW			sys_insn(1, 0, 7, 6, 2)

-- 
2.48.0