linux-kernel - [PATCH v2 12/15] RISC-V: KVM: add SBI extension init()/deinit() functions

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Message-ID: <20250210213549.1867704-13-cleger@rivosinc.com>
Date: Mon, 10 Feb 2025 22:35:45 +0100
From: Clément Léger <cleger@...osinc.com>
To: Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Anup Patel <anup@...infault.org>,
	Atish Patra <atishp@...shpatra.org>,
	Shuah Khan <shuah@...nel.org>,
	Jonathan Corbet <corbet@....net>,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org,
	kvm@...r.kernel.org,
	kvm-riscv@...ts.infradead.org,
	linux-kselftest@...r.kernel.org
Cc: Clément Léger <cleger@...osinc.com>,
	Samuel Holland <samuel.holland@...ive.com>
Subject: [PATCH v2 12/15] RISC-V: KVM: add SBI extension init()/deinit() functions

The FWFT SBI extension will need to dynamically allocate memory and do
init time specific initialization. Add an init/deinit callbacks that
allows to do so.

Signed-off-by: Clément Léger <cleger@...osinc.com>
---
 arch/riscv/include/asm/kvm_vcpu_sbi.h |  9 ++++++++
 arch/riscv/kvm/vcpu.c                 |  2 ++
 arch/riscv/kvm/vcpu_sbi.c             | 30 +++++++++++++++++++++++++++
 3 files changed, 41 insertions(+)

diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h
index 4ed6203cdd30..bcb90757b149 100644
--- a/arch/riscv/include/asm/kvm_vcpu_sbi.h
+++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h
@@ -49,6 +49,14 @@ struct kvm_vcpu_sbi_extension {
 
 	/* Extension specific probe function */
 	unsigned long (*probe)(struct kvm_vcpu *vcpu);
+
+	/*
+	 * Init/deinit function called once during VCPU init/destroy. These
+	 * might be use if the SBI extensions need to allocate or do specific
+	 * init time only configuration.
+	 */
+	int (*init)(struct kvm_vcpu *vcpu);
+	void (*deinit)(struct kvm_vcpu *vcpu);
 };
 
 void kvm_riscv_vcpu_sbi_forward(struct kvm_vcpu *vcpu, struct kvm_run *run);
@@ -69,6 +77,7 @@ const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext(
 bool riscv_vcpu_supports_sbi_ext(struct kvm_vcpu *vcpu, int idx);
 int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu, struct kvm_run *run);
 void kvm_riscv_vcpu_sbi_init(struct kvm_vcpu *vcpu);
+void kvm_riscv_vcpu_sbi_deinit(struct kvm_vcpu *vcpu);
 
 int kvm_riscv_vcpu_get_reg_sbi_sta(struct kvm_vcpu *vcpu, unsigned long reg_num,
 				   unsigned long *reg_val);
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 60d684c76c58..877bcc85c067 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -185,6 +185,8 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
 
 void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
 {
+	kvm_riscv_vcpu_sbi_deinit(vcpu);
+
 	/* Cleanup VCPU AIA context */
 	kvm_riscv_vcpu_aia_deinit(vcpu);
 
diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c
index d1c83a77735e..44f551143498 100644
--- a/arch/riscv/kvm/vcpu_sbi.c
+++ b/arch/riscv/kvm/vcpu_sbi.c
@@ -505,8 +505,38 @@ void kvm_riscv_vcpu_sbi_init(struct kvm_vcpu *vcpu)
 			continue;
 		}
 
+		if (!ext->default_disabled && ext->init &&
+		    ext->init(vcpu) != 0) {
+			    scontext->ext_status[idx] =
+				    KVM_RISCV_SBI_EXT_STATUS_UNAVAILABLE;
+			    continue;
+		}
+
 		scontext->ext_status[idx] = ext->default_disabled ?
 					KVM_RISCV_SBI_EXT_STATUS_DISABLED :
 					KVM_RISCV_SBI_EXT_STATUS_ENABLED;
 	}
 }
+
+void kvm_riscv_vcpu_sbi_deinit(struct kvm_vcpu *vcpu)
+{
+	struct kvm_vcpu_sbi_context *scontext = &vcpu->arch.sbi_context;
+	const struct kvm_riscv_sbi_extension_entry *entry;
+	const struct kvm_vcpu_sbi_extension *ext;
+	int idx, i;
+
+	for (i = 0; i < ARRAY_SIZE(sbi_ext); i++) {
+		entry = &sbi_ext[i];
+		ext = entry->ext_ptr;
+		idx = entry->ext_idx;
+
+		if (idx < 0 || idx >= ARRAY_SIZE(scontext->ext_status))
+			continue;
+
+		if (scontext->ext_status[idx] == KVM_RISCV_SBI_EXT_STATUS_UNAVAILABLE ||
+		    !ext->deinit)
+			continue;
+
+		ext->deinit(vcpu);
+	}
+}
-- 
2.47.2