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@rivosinc.com>
Reviewed-by: Deepak Gupta <debug@rivosinc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20250523101932.1594077-15-cleger@rivosinc.com
Signed-off-by: Anup Patel <anup@brainfault.org>

diff --git a/arch/riscv/kvm/vcpu_sbi_fwft.c b/arch/riscv/kvm/vcpu_sbi_fwft.c
index b0f66c7bf010e96634730d870819be6004854499..6770c043bbcb358f56747a1917c8d154e2b9cea6 100644 (file)
--- 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 *