[PATCH v3 17/17] RISC-V: KVM: add support for SBI_FWFT_MISALIGNED_DELEG

["Clément Léger" <cleger@rivosinc.com>]

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@rivosinc.com>
Reviewed-by: Deepak Gupta <debug@rivosinc.com>
---
 arch/riscv/kvm/vcpu.c          |  3 +++
 arch/riscv/kvm/vcpu_sbi_fwft.c | 39 ++++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 542747e2c7f5..d98e379945c3 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -646,6 +646,7 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 {
 	void *nsh;
 	struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
+	struct kvm_vcpu_config *cfg = &vcpu->arch.cfg;
 
 	vcpu->cpu = -1;
 
@@ -671,6 +672,7 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 		csr->vstval = nacl_csr_read(nsh, CSR_VSTVAL);
 		csr->hvip = nacl_csr_read(nsh, CSR_HVIP);
 		csr->vsatp = nacl_csr_read(nsh, CSR_VSATP);
+		cfg->hedeleg = nacl_csr_read(nsh, CSR_HEDELEG);
 	} else {
 		csr->vsstatus = csr_read(CSR_VSSTATUS);
 		csr->vsie = csr_read(CSR_VSIE);
@@ -681,6 +683,7 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 		csr->vstval = csr_read(CSR_VSTVAL);
 		csr->hvip = csr_read(CSR_HVIP);
 		csr->vsatp = csr_read(CSR_VSATP);
+		cfg->hedeleg = csr_read(CSR_HEDELEG);
 	}
 }
 
diff --git a/arch/riscv/kvm/vcpu_sbi_fwft.c b/arch/riscv/kvm/vcpu_sbi_fwft.c
index cce1e41d5490..756fda1cf2e7 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
@@ -64,7 +66,44 @@ 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)
+{
+	if (!misaligned_traps_can_delegate())
+		return false;
+
+	return true;
+}
+
+static int kvm_sbi_fwft_set_misaligned_delegation(struct kvm_vcpu *vcpu,
+					struct kvm_sbi_fwft_config *conf,
+					unsigned long value)
+{
+	if (value == 1)
+		csr_set(CSR_HEDELEG, MIS_DELEG);
+	else if (value == 0)
+		csr_clear(CSR_HEDELEG, MIS_DELEG);
+	else
+		return SBI_ERR_INVALID_PARAM;
+
+	return SBI_SUCCESS;
+}
+
+static int 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) != 0;
+
+	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 *
-- 
2.47.2