linux-kernel - [PATCH V12 09/14] RISC-V: paravirt: Add pvqspinlock KVM backend

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Date: Mon, 25 Dec 2023 07:58:42 -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 09/14] RISC-V: paravirt: Add pvqspinlock KVM backend

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

Add the files functions needed to support the SBI PVLOCK (paravirt
qspinlock kick_cpu) extension. Implement kvm_sbi_ext_pvlock_kick_-
cpu(), and we only need to call the kvm_vcpu_kick() and bring
target_vcpu from the halt state. No irq raised, no other request,
just a pure vcpu_kick.

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/kvm_vcpu_sbi.h |  1 +
 arch/riscv/include/uapi/asm/kvm.h     |  1 +
 arch/riscv/kvm/Makefile               |  1 +
 arch/riscv/kvm/vcpu_sbi.c             |  4 ++
 arch/riscv/kvm/vcpu_sbi_pvlock.c      | 57 +++++++++++++++++++++++++++
 5 files changed, 64 insertions(+)
 create mode 100644 arch/riscv/kvm/vcpu_sbi_pvlock.c

diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h
index 6a453f7f8b56..a051e4875542 100644
--- a/arch/riscv/include/asm/kvm_vcpu_sbi.h
+++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h
@@ -76,6 +76,7 @@ extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_hsm;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_dbcn;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_experimental;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_vendor;
+extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_pvlock;
 
 #ifdef CONFIG_RISCV_PMU_SBI
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_pmu;
diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
index 60d3b21dead7..24bbada1a9fb 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -157,6 +157,7 @@ enum KVM_RISCV_SBI_EXT_ID {
 	KVM_RISCV_SBI_EXT_EXPERIMENTAL,
 	KVM_RISCV_SBI_EXT_VENDOR,
 	KVM_RISCV_SBI_EXT_DBCN,
+	KVM_RISCV_SBI_EXT_PVLOCK,
 	KVM_RISCV_SBI_EXT_MAX,
 };
 
diff --git a/arch/riscv/kvm/Makefile b/arch/riscv/kvm/Makefile
index 4c2067fc59fc..6112750a3a0c 100644
--- a/arch/riscv/kvm/Makefile
+++ b/arch/riscv/kvm/Makefile
@@ -26,6 +26,7 @@ kvm-$(CONFIG_RISCV_SBI_V01) += vcpu_sbi_v01.o
 kvm-y += vcpu_sbi_base.o
 kvm-y += vcpu_sbi_replace.o
 kvm-y += vcpu_sbi_hsm.o
+kvm-y += vcpu_sbi_pvlock.o
 kvm-y += vcpu_timer.o
 kvm-$(CONFIG_RISCV_PMU_SBI) += vcpu_pmu.o vcpu_sbi_pmu.o
 kvm-y += aia.o
diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c
index a04ff98085d9..7078bd57806b 100644
--- a/arch/riscv/kvm/vcpu_sbi.c
+++ b/arch/riscv/kvm/vcpu_sbi.c
@@ -78,6 +78,10 @@ static const struct kvm_riscv_sbi_extension_entry sbi_ext[] = {
 		.ext_idx = KVM_RISCV_SBI_EXT_VENDOR,
 		.ext_ptr = &vcpu_sbi_ext_vendor,
 	},
+	{
+		.ext_idx = KVM_RISCV_SBI_EXT_PVLOCK,
+		.ext_ptr = &vcpu_sbi_ext_pvlock,
+	},
 };
 
 void kvm_riscv_vcpu_sbi_forward(struct kvm_vcpu *vcpu, struct kvm_run *run)
diff --git a/arch/riscv/kvm/vcpu_sbi_pvlock.c b/arch/riscv/kvm/vcpu_sbi_pvlock.c
new file mode 100644
index 000000000000..914fc58aedfe
--- /dev/null
+++ b/arch/riscv/kvm/vcpu_sbi_pvlock.c
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c), 2023 Alibaba Cloud
+ *
+ * Authors:
+ *     Guo Ren <guoren@...ux.alibaba.com>
+ */
+
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/kvm_host.h>
+#include <asm/sbi.h>
+#include <asm/kvm_vcpu_sbi.h>
+
+static int kvm_sbi_ext_pvlock_kick_cpu(struct kvm_vcpu *vcpu)
+{
+	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
+	struct kvm *kvm = vcpu->kvm;
+	struct kvm_vcpu *target;
+
+	target = kvm_get_vcpu_by_id(kvm, cp->a0);
+	if (!target)
+		return SBI_ERR_INVALID_PARAM;
+
+	kvm_vcpu_kick(target);
+
+	if (READ_ONCE(target->ready))
+		kvm_vcpu_yield_to(target);
+
+	return SBI_SUCCESS;
+}
+
+static int kvm_sbi_ext_pvlock_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
+				      struct kvm_vcpu_sbi_return *retdata)
+{
+	int ret = 0;
+	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
+	unsigned long funcid = cp->a6;
+
+	switch (funcid) {
+	case SBI_EXT_PVLOCK_KICK_CPU:
+		ret = kvm_sbi_ext_pvlock_kick_cpu(vcpu);
+		break;
+	default:
+		ret = SBI_ERR_NOT_SUPPORTED;
+	}
+
+	retdata->err_val = ret;
+
+	return 0;
+}
+
+const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_pvlock = {
+	.extid_start = SBI_EXT_PVLOCK,
+	.extid_end = SBI_EXT_PVLOCK,
+	.handler = kvm_sbi_ext_pvlock_handler,
+};
-- 
2.40.1