linux-kernel - [PATCH V12 11/14] RISC-V: paravirt: pvqspinlock: Add SBI implementation

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Message-Id: <20231225125847.2778638-12-guoren@kernel.org>
Date: Mon, 25 Dec 2023 07:58:44 -0500
From: guoren@...nel.org
To: paul.walmsley@...ive.com,
	palmer@...belt.com,
	guoren@...nel.org,
	panqinglin2020@...as.ac.cn,
	bjorn@...osinc.com,
	conor.dooley@...rochip.com,
	leobras@...hat.com,
	peterz@...radead.org,
	anup@...infault.org,
	keescook@...omium.org,
	wuwei2016@...as.ac.cn,
	xiaoguang.xing@...hgo.com,
	chao.wei@...hgo.com,
	unicorn_wang@...look.com,
	uwu@...nowy.me,
	jszhang@...nel.org,
	wefu@...hat.com,
	atishp@...shpatra.org
Cc: linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org,
	virtualization@...ts.linux-foundation.org,
	Guo Ren <guoren@...ux.alibaba.com>
Subject: [PATCH V12 11/14] RISC-V: paravirt: pvqspinlock: Add SBI implementation

From: Guo Ren <guoren@...ux.alibaba.com>

Implement pv_kick with SBI guest implementation, and add
SBI_EXT_PVLOCK extension detection. The backend part is
in the KVM pvqspinlock patch.

Reviewed-by: Leonardo Bras <leobras@...hat.com>
Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
Signed-off-by: Guo Ren <guoren@...nel.org>
---
 arch/riscv/include/asm/sbi.h           | 6 ++++++
 arch/riscv/kernel/qspinlock_paravirt.c | 7 ++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
index 8f748d9e1b85..318b3dd92958 100644
--- a/arch/riscv/include/asm/sbi.h
+++ b/arch/riscv/include/asm/sbi.h
@@ -31,6 +31,7 @@ enum sbi_ext_id {
 	SBI_EXT_SRST = 0x53525354,
 	SBI_EXT_PMU = 0x504D55,
 	SBI_EXT_DBCN = 0x4442434E,
+	SBI_EXT_PVLOCK = 0xAB0401,
 
 	/* Experimentals extensions must lie within this range */
 	SBI_EXT_EXPERIMENTAL_START = 0x08000000,
@@ -250,6 +251,11 @@ enum sbi_ext_dbcn_fid {
 	SBI_EXT_DBCN_CONSOLE_WRITE_BYTE = 2,
 };
 
+/* kick cpu out of wfi */
+enum sbi_ext_pvlock_fid {
+	SBI_EXT_PVLOCK_KICK_CPU = 0,
+};
+
 #define SBI_SPEC_VERSION_DEFAULT	0x1
 #define SBI_SPEC_VERSION_MAJOR_SHIFT	24
 #define SBI_SPEC_VERSION_MAJOR_MASK	0x7f
diff --git a/arch/riscv/kernel/qspinlock_paravirt.c b/arch/riscv/kernel/qspinlock_paravirt.c
index 85ff5a3ec234..7d1b99412222 100644
--- a/arch/riscv/kernel/qspinlock_paravirt.c
+++ b/arch/riscv/kernel/qspinlock_paravirt.c
@@ -11,6 +11,8 @@
 
 void pv_kick(int cpu)
 {
+	sbi_ecall(SBI_EXT_PVLOCK, SBI_EXT_PVLOCK_KICK_CPU,
+		  cpuid_to_hartid_map(cpu), 0, 0, 0, 0, 0);
 	return;
 }
 
@@ -25,7 +27,7 @@ void pv_wait(u8 *ptr, u8 val)
 	if (READ_ONCE(*ptr) != val)
 		goto out;
 
-	/* wait_for_interrupt(); */
+	wait_for_interrupt();
 out:
 	local_irq_restore(flags);
 }
@@ -49,6 +51,9 @@ void __init pv_qspinlock_init(void)
 	if(sbi_get_firmware_id() != SBI_EXT_BASE_IMPL_ID_KVM)
 		return;
 
+	if (!sbi_probe_extension(SBI_EXT_PVLOCK))
+		return;
+
 	pr_info("PV qspinlocks enabled\n");
 	__pv_init_lock_hash();
 
-- 
2.40.1