linux-kernel - [PATCH v8 14/14] RISC-V: KVM: add support for SBI_FWFT_MISALIGNED

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Message-ID: <20250523101932.1594077-15-cleger@rivosinc.com>
Date: Fri, 23 May 2025 12:19:31 +0200
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>,
	Andrew Jones <ajones@...tanamicro.com>,
	Deepak Gupta <debug@...osinc.com>,
	Charlie Jenkins <charlie@...osinc.com>,
	Atish Patra <atishp@...osinc.com>
Subject: [PATCH v8 14/14] RISC-V: KVM: add support for SBI_FWFT_MISALIGNED_DELEG

SBI_FWFT_MISALIGNED_DELEG needs hedeleg to be modified to delegate
misaligned load/store exceptions. Save and restore it during CPU
load/put.

Signed-off-by: Clément Léger <cleger@...osinc.com>
Reviewed-by: Deepak Gupta <debug@...osinc.com>
Reviewed-by: Andrew Jones <ajones@...tanamicro.com>
Reviewed-by: Atish Patra <atishp@...osinc.com>
---
 arch/riscv/kvm/vcpu_sbi_fwft.c | 41 ++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/arch/riscv/kvm/vcpu_sbi_fwft.c b/arch/riscv/kvm/vcpu_sbi_fwft.c
index b0f66c7bf010..6770c043bbcb 100644
--- a/arch/riscv/kvm/vcpu_sbi_fwft.c
+++ b/arch/riscv/kvm/vcpu_sbi_fwft.c
@@ -14,6 +14,8 @@
 #include <asm/kvm_vcpu_sbi.h>
 #include <asm/kvm_vcpu_sbi_fwft.h>
 
+#define MIS_DELEG (BIT_ULL(EXC_LOAD_MISALIGNED) | BIT_ULL(EXC_STORE_MISALIGNED))
+
 struct kvm_sbi_fwft_feature {
 	/**
 	 * @id: Feature ID
@@ -68,7 +70,46 @@ static bool kvm_fwft_is_defined_feature(enum sbi_fwft_feature_t feature)
 	return false;
 }
 
+static bool kvm_sbi_fwft_misaligned_delegation_supported(struct kvm_vcpu *vcpu)
+{
+	return misaligned_traps_can_delegate();
+}
+
+static long kvm_sbi_fwft_set_misaligned_delegation(struct kvm_vcpu *vcpu,
+					struct kvm_sbi_fwft_config *conf,
+					unsigned long value)
+{
+	struct kvm_vcpu_config *cfg = &vcpu->arch.cfg;
+
+	if (value == 1) {
+		cfg->hedeleg |= MIS_DELEG;
+		csr_set(CSR_HEDELEG, MIS_DELEG);
+	} else if (value == 0) {
+		cfg->hedeleg &= ~MIS_DELEG;
+		csr_clear(CSR_HEDELEG, MIS_DELEG);
+	} else {
+		return SBI_ERR_INVALID_PARAM;
+	}
+
+	return SBI_SUCCESS;
+}
+
+static long kvm_sbi_fwft_get_misaligned_delegation(struct kvm_vcpu *vcpu,
+					struct kvm_sbi_fwft_config *conf,
+					unsigned long *value)
+{
+	*value = (csr_read(CSR_HEDELEG) & MIS_DELEG) == MIS_DELEG;
+
+	return SBI_SUCCESS;
+}
+
 static const struct kvm_sbi_fwft_feature features[] = {
+	{
+		.id = SBI_FWFT_MISALIGNED_EXC_DELEG,
+		.supported = kvm_sbi_fwft_misaligned_delegation_supported,
+		.set = kvm_sbi_fwft_set_misaligned_delegation,
+		.get = kvm_sbi_fwft_get_misaligned_delegation,
+	},
 };
 
 static struct kvm_sbi_fwft_config *
-- 
2.49.0