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19bff88e65
The M-mode redirects an unhandled misaligned trap back to S-mode when not delegating it to VS-mode(hedeleg). However, KVM running in HS-mode terminates the VS-mode software when back from M-mode. The KVM should redirect the trap back to VS-mode, and let VS-mode trap handler decide the next step. Here is a way to handle misaligned traps in KVM, not only directing them to VS-mode or terminate it. Signed-off-by: wchen <waylingII@gmail.com> Reviewed-by: Anup Patel <anup@brainfault.org> Signed-off-by: Anup Patel <anup@brainfault.org>
224 lines
5.6 KiB
C
224 lines
5.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2019 Western Digital Corporation or its affiliates.
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*
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* Authors:
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* Anup Patel <anup.patel@wdc.com>
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*/
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#include <linux/kvm_host.h>
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#include <asm/csr.h>
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#include <asm/insn-def.h>
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static int gstage_page_fault(struct kvm_vcpu *vcpu, struct kvm_run *run,
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struct kvm_cpu_trap *trap)
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{
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struct kvm_memory_slot *memslot;
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unsigned long hva, fault_addr;
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bool writable;
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gfn_t gfn;
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int ret;
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fault_addr = (trap->htval << 2) | (trap->stval & 0x3);
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gfn = fault_addr >> PAGE_SHIFT;
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memslot = gfn_to_memslot(vcpu->kvm, gfn);
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hva = gfn_to_hva_memslot_prot(memslot, gfn, &writable);
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if (kvm_is_error_hva(hva) ||
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(trap->scause == EXC_STORE_GUEST_PAGE_FAULT && !writable)) {
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switch (trap->scause) {
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case EXC_LOAD_GUEST_PAGE_FAULT:
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return kvm_riscv_vcpu_mmio_load(vcpu, run,
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fault_addr,
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trap->htinst);
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case EXC_STORE_GUEST_PAGE_FAULT:
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return kvm_riscv_vcpu_mmio_store(vcpu, run,
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fault_addr,
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trap->htinst);
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default:
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return -EOPNOTSUPP;
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};
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}
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ret = kvm_riscv_gstage_map(vcpu, memslot, fault_addr, hva,
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(trap->scause == EXC_STORE_GUEST_PAGE_FAULT) ? true : false);
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if (ret < 0)
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return ret;
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return 1;
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}
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/**
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* kvm_riscv_vcpu_unpriv_read -- Read machine word from Guest memory
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*
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* @vcpu: The VCPU pointer
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* @read_insn: Flag representing whether we are reading instruction
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* @guest_addr: Guest address to read
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* @trap: Output pointer to trap details
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*/
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unsigned long kvm_riscv_vcpu_unpriv_read(struct kvm_vcpu *vcpu,
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bool read_insn,
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unsigned long guest_addr,
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struct kvm_cpu_trap *trap)
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{
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register unsigned long taddr asm("a0") = (unsigned long)trap;
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register unsigned long ttmp asm("a1");
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unsigned long flags, val, tmp, old_stvec, old_hstatus;
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local_irq_save(flags);
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old_hstatus = csr_swap(CSR_HSTATUS, vcpu->arch.guest_context.hstatus);
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old_stvec = csr_swap(CSR_STVEC, (ulong)&__kvm_riscv_unpriv_trap);
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if (read_insn) {
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/*
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* HLVX.HU instruction
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* 0110010 00011 rs1 100 rd 1110011
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*/
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asm volatile ("\n"
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".option push\n"
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".option norvc\n"
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"add %[ttmp], %[taddr], 0\n"
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HLVX_HU(%[val], %[addr])
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"andi %[tmp], %[val], 3\n"
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"addi %[tmp], %[tmp], -3\n"
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"bne %[tmp], zero, 2f\n"
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"addi %[addr], %[addr], 2\n"
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HLVX_HU(%[tmp], %[addr])
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"sll %[tmp], %[tmp], 16\n"
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"add %[val], %[val], %[tmp]\n"
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"2:\n"
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".option pop"
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: [val] "=&r" (val), [tmp] "=&r" (tmp),
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[taddr] "+&r" (taddr), [ttmp] "+&r" (ttmp),
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[addr] "+&r" (guest_addr) : : "memory");
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if (trap->scause == EXC_LOAD_PAGE_FAULT)
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trap->scause = EXC_INST_PAGE_FAULT;
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} else {
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/*
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* HLV.D instruction
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* 0110110 00000 rs1 100 rd 1110011
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*
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* HLV.W instruction
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* 0110100 00000 rs1 100 rd 1110011
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*/
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asm volatile ("\n"
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".option push\n"
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".option norvc\n"
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"add %[ttmp], %[taddr], 0\n"
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#ifdef CONFIG_64BIT
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HLV_D(%[val], %[addr])
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#else
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HLV_W(%[val], %[addr])
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#endif
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".option pop"
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: [val] "=&r" (val),
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[taddr] "+&r" (taddr), [ttmp] "+&r" (ttmp)
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: [addr] "r" (guest_addr) : "memory");
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}
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csr_write(CSR_STVEC, old_stvec);
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csr_write(CSR_HSTATUS, old_hstatus);
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local_irq_restore(flags);
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return val;
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}
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/**
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* kvm_riscv_vcpu_trap_redirect -- Redirect trap to Guest
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*
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* @vcpu: The VCPU pointer
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* @trap: Trap details
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*/
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void kvm_riscv_vcpu_trap_redirect(struct kvm_vcpu *vcpu,
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struct kvm_cpu_trap *trap)
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{
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unsigned long vsstatus = csr_read(CSR_VSSTATUS);
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/* Change Guest SSTATUS.SPP bit */
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vsstatus &= ~SR_SPP;
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if (vcpu->arch.guest_context.sstatus & SR_SPP)
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vsstatus |= SR_SPP;
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/* Change Guest SSTATUS.SPIE bit */
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vsstatus &= ~SR_SPIE;
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if (vsstatus & SR_SIE)
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vsstatus |= SR_SPIE;
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/* Clear Guest SSTATUS.SIE bit */
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vsstatus &= ~SR_SIE;
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/* Update Guest SSTATUS */
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csr_write(CSR_VSSTATUS, vsstatus);
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/* Update Guest SCAUSE, STVAL, and SEPC */
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csr_write(CSR_VSCAUSE, trap->scause);
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csr_write(CSR_VSTVAL, trap->stval);
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csr_write(CSR_VSEPC, trap->sepc);
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/* Set Guest PC to Guest exception vector */
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vcpu->arch.guest_context.sepc = csr_read(CSR_VSTVEC);
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/* Set Guest privilege mode to supervisor */
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vcpu->arch.guest_context.sstatus |= SR_SPP;
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}
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/*
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* Return > 0 to return to guest, < 0 on error, 0 (and set exit_reason) on
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* proper exit to userspace.
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*/
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int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
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struct kvm_cpu_trap *trap)
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{
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int ret;
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/* If we got host interrupt then do nothing */
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if (trap->scause & CAUSE_IRQ_FLAG)
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return 1;
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/* Handle guest traps */
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ret = -EFAULT;
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run->exit_reason = KVM_EXIT_UNKNOWN;
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switch (trap->scause) {
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case EXC_INST_ILLEGAL:
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case EXC_LOAD_MISALIGNED:
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case EXC_STORE_MISALIGNED:
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if (vcpu->arch.guest_context.hstatus & HSTATUS_SPV) {
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kvm_riscv_vcpu_trap_redirect(vcpu, trap);
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ret = 1;
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}
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break;
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case EXC_VIRTUAL_INST_FAULT:
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if (vcpu->arch.guest_context.hstatus & HSTATUS_SPV)
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ret = kvm_riscv_vcpu_virtual_insn(vcpu, run, trap);
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break;
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case EXC_INST_GUEST_PAGE_FAULT:
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case EXC_LOAD_GUEST_PAGE_FAULT:
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case EXC_STORE_GUEST_PAGE_FAULT:
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if (vcpu->arch.guest_context.hstatus & HSTATUS_SPV)
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ret = gstage_page_fault(vcpu, run, trap);
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break;
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case EXC_SUPERVISOR_SYSCALL:
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if (vcpu->arch.guest_context.hstatus & HSTATUS_SPV)
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ret = kvm_riscv_vcpu_sbi_ecall(vcpu, run);
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break;
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default:
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break;
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}
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/* Print details in-case of error */
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if (ret < 0) {
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kvm_err("VCPU exit error %d\n", ret);
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kvm_err("SEPC=0x%lx SSTATUS=0x%lx HSTATUS=0x%lx\n",
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vcpu->arch.guest_context.sepc,
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vcpu->arch.guest_context.sstatus,
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vcpu->arch.guest_context.hstatus);
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kvm_err("SCAUSE=0x%lx STVAL=0x%lx HTVAL=0x%lx HTINST=0x%lx\n",
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trap->scause, trap->stval, trap->htval, trap->htinst);
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}
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return ret;
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}
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