On 03/10/19 07:07, Anup Patel wrote: > We will get stage2 page faults whenever Guest/VM access SW emulated > MMIO device or unmapped Guest RAM. > > This patch implements MMIO read/write emulation by extracting MMIO > details from the trapped load/store instruction and forwarding the > MMIO read/write to user-space. The actual MMIO emulation will happen > in user-space and KVM kernel module will only take care of register > updates before resuming the trapped VCPU. > > The handling for stage2 page faults for unmapped Guest RAM will be > implemeted by a separate patch later. > > Signed-off-by: Anup Patel <anup.patel@xxxxxxx> > Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> > Reviewed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> > Reviewed-by: Alexander Graf <graf@xxxxxxxxxx> The changes look good. Paolo > --- > arch/riscv/include/asm/kvm_host.h | 20 ++ > arch/riscv/kvm/mmu.c | 7 + > arch/riscv/kvm/vcpu_exit.c | 505 +++++++++++++++++++++++++++++- > arch/riscv/kvm/vcpu_switch.S | 14 + > 4 files changed, 543 insertions(+), 3 deletions(-) > > diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h > index 18f1097f1d8d..2a5209fff68d 100644 > --- a/arch/riscv/include/asm/kvm_host.h > +++ b/arch/riscv/include/asm/kvm_host.h > @@ -53,6 +53,13 @@ struct kvm_arch { > phys_addr_t pgd_phys; > }; > > +struct kvm_mmio_decode { > + unsigned long insn; > + int len; > + int shift; > + int return_handled; > +}; > + > struct kvm_cpu_context { > unsigned long zero; > unsigned long ra; > @@ -141,6 +148,9 @@ struct kvm_vcpu_arch { > unsigned long irqs_pending; > unsigned long irqs_pending_mask; > > + /* MMIO instruction details */ > + struct kvm_mmio_decode mmio_decode; > + > /* VCPU power-off state */ > bool power_off; > > @@ -160,11 +170,21 @@ static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {} > int kvm_riscv_setup_vsip(void); > void kvm_riscv_cleanup_vsip(void); > > +int kvm_riscv_stage2_map(struct kvm_vcpu *vcpu, gpa_t gpa, unsigned long hva, > + bool is_write); > void kvm_riscv_stage2_flush_cache(struct kvm_vcpu *vcpu); > int kvm_riscv_stage2_alloc_pgd(struct kvm *kvm); > void kvm_riscv_stage2_free_pgd(struct kvm *kvm); > void kvm_riscv_stage2_update_hgatp(struct kvm_vcpu *vcpu); > > +void __kvm_riscv_unpriv_trap(void); > + > +unsigned long kvm_riscv_vcpu_unpriv_read(struct kvm_vcpu *vcpu, > + bool read_insn, > + unsigned long guest_addr, > + unsigned long *trap_scause); > +void kvm_riscv_vcpu_trap_redirect(struct kvm_vcpu *vcpu, > + unsigned long scause, unsigned long stval); > int kvm_riscv_vcpu_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run); > int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run, > unsigned long scause, unsigned long stval); > diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c > index 04dd089b86ff..2b965f9aac07 100644 > --- a/arch/riscv/kvm/mmu.c > +++ b/arch/riscv/kvm/mmu.c > @@ -61,6 +61,13 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, > return 0; > } > > +int kvm_riscv_stage2_map(struct kvm_vcpu *vcpu, gpa_t gpa, unsigned long hva, > + bool is_write) > +{ > + /* TODO: */ > + return 0; > +} > + > void kvm_riscv_stage2_flush_cache(struct kvm_vcpu *vcpu) > { > /* TODO: */ > diff --git a/arch/riscv/kvm/vcpu_exit.c b/arch/riscv/kvm/vcpu_exit.c > index e4d7c8f0807a..f1378c0a447f 100644 > --- a/arch/riscv/kvm/vcpu_exit.c > +++ b/arch/riscv/kvm/vcpu_exit.c > @@ -6,9 +6,430 @@ > * Anup Patel <anup.patel@xxxxxxx> > */ > > +#include <linux/bitops.h> > #include <linux/errno.h> > #include <linux/err.h> > #include <linux/kvm_host.h> > +#include <asm/csr.h> > + > +#define INSN_MATCH_LB 0x3 > +#define INSN_MASK_LB 0x707f > +#define INSN_MATCH_LH 0x1003 > +#define INSN_MASK_LH 0x707f > +#define INSN_MATCH_LW 0x2003 > +#define INSN_MASK_LW 0x707f > +#define INSN_MATCH_LD 0x3003 > +#define INSN_MASK_LD 0x707f > +#define INSN_MATCH_LBU 0x4003 > +#define INSN_MASK_LBU 0x707f > +#define INSN_MATCH_LHU 0x5003 > +#define INSN_MASK_LHU 0x707f > +#define INSN_MATCH_LWU 0x6003 > +#define INSN_MASK_LWU 0x707f > +#define INSN_MATCH_SB 0x23 > +#define INSN_MASK_SB 0x707f > +#define INSN_MATCH_SH 0x1023 > +#define INSN_MASK_SH 0x707f > +#define INSN_MATCH_SW 0x2023 > +#define INSN_MASK_SW 0x707f > +#define INSN_MATCH_SD 0x3023 > +#define INSN_MASK_SD 0x707f > + > +#define INSN_MATCH_C_LD 0x6000 > +#define INSN_MASK_C_LD 0xe003 > +#define INSN_MATCH_C_SD 0xe000 > +#define INSN_MASK_C_SD 0xe003 > +#define INSN_MATCH_C_LW 0x4000 > +#define INSN_MASK_C_LW 0xe003 > +#define INSN_MATCH_C_SW 0xc000 > +#define INSN_MASK_C_SW 0xe003 > +#define INSN_MATCH_C_LDSP 0x6002 > +#define INSN_MASK_C_LDSP 0xe003 > +#define INSN_MATCH_C_SDSP 0xe002 > +#define INSN_MASK_C_SDSP 0xe003 > +#define INSN_MATCH_C_LWSP 0x4002 > +#define INSN_MASK_C_LWSP 0xe003 > +#define INSN_MATCH_C_SWSP 0xc002 > +#define INSN_MASK_C_SWSP 0xe003 > + > +#define INSN_16BIT_MASK 0x3 > + > +#define INSN_IS_16BIT(insn) (((insn) & INSN_16BIT_MASK) != INSN_16BIT_MASK) > + > +#define INSN_LEN(insn) (INSN_IS_16BIT(insn) ? 2 : 4) > + > +#ifdef CONFIG_64BIT > +#define LOG_REGBYTES 3 > +#else > +#define LOG_REGBYTES 2 > +#endif > +#define REGBYTES (1 << LOG_REGBYTES) > + > +#define SH_RD 7 > +#define SH_RS1 15 > +#define SH_RS2 20 > +#define SH_RS2C 2 > + > +#define RV_X(x, s, n) (((x) >> (s)) & ((1 << (n)) - 1)) > +#define RVC_LW_IMM(x) ((RV_X(x, 6, 1) << 2) | \ > + (RV_X(x, 10, 3) << 3) | \ > + (RV_X(x, 5, 1) << 6)) > +#define RVC_LD_IMM(x) ((RV_X(x, 10, 3) << 3) | \ > + (RV_X(x, 5, 2) << 6)) > +#define RVC_LWSP_IMM(x) ((RV_X(x, 4, 3) << 2) | \ > + (RV_X(x, 12, 1) << 5) | \ > + (RV_X(x, 2, 2) << 6)) > +#define RVC_LDSP_IMM(x) ((RV_X(x, 5, 2) << 3) | \ > + (RV_X(x, 12, 1) << 5) | \ > + (RV_X(x, 2, 3) << 6)) > +#define RVC_SWSP_IMM(x) ((RV_X(x, 9, 4) << 2) | \ > + (RV_X(x, 7, 2) << 6)) > +#define RVC_SDSP_IMM(x) ((RV_X(x, 10, 3) << 3) | \ > + (RV_X(x, 7, 3) << 6)) > +#define RVC_RS1S(insn) (8 + RV_X(insn, SH_RD, 3)) > +#define RVC_RS2S(insn) (8 + RV_X(insn, SH_RS2C, 3)) > +#define RVC_RS2(insn) RV_X(insn, SH_RS2C, 5) > + > +#define SHIFT_RIGHT(x, y) \ > + ((y) < 0 ? ((x) << -(y)) : ((x) >> (y))) > + > +#define REG_MASK \ > + ((1 << (5 + LOG_REGBYTES)) - (1 << LOG_REGBYTES)) > + > +#define REG_OFFSET(insn, pos) \ > + (SHIFT_RIGHT((insn), (pos) - LOG_REGBYTES) & REG_MASK) > + > +#define REG_PTR(insn, pos, regs) \ > + (ulong *)((ulong)(regs) + REG_OFFSET(insn, pos)) > + > +#define GET_RM(insn) (((insn) >> 12) & 7) > + > +#define GET_RS1(insn, regs) (*REG_PTR(insn, SH_RS1, regs)) > +#define GET_RS2(insn, regs) (*REG_PTR(insn, SH_RS2, regs)) > +#define GET_RS1S(insn, regs) (*REG_PTR(RVC_RS1S(insn), 0, regs)) > +#define GET_RS2S(insn, regs) (*REG_PTR(RVC_RS2S(insn), 0, regs)) > +#define GET_RS2C(insn, regs) (*REG_PTR(insn, SH_RS2C, regs)) > +#define GET_SP(regs) (*REG_PTR(2, 0, regs)) > +#define SET_RD(insn, regs, val) (*REG_PTR(insn, SH_RD, regs) = (val)) > +#define IMM_I(insn) ((s32)(insn) >> 20) > +#define IMM_S(insn) (((s32)(insn) >> 25 << 5) | \ > + (s32)(((insn) >> 7) & 0x1f)) > +#define MASK_FUNCT3 0x7000 > + > +static int emulate_load(struct kvm_vcpu *vcpu, struct kvm_run *run, > + unsigned long fault_addr) > +{ > + int shift = 0, len = 0; > + unsigned long ut_scause = 0; > + struct kvm_cpu_context *ct = &vcpu->arch.guest_context; > + ulong insn = kvm_riscv_vcpu_unpriv_read(vcpu, true, ct->sepc, > + &ut_scause); > + > + /* Redirect trap if we failed to read instruction */ > + if (ut_scause) { > + if (ut_scause == EXC_LOAD_PAGE_FAULT) > + ut_scause = EXC_INST_PAGE_FAULT; > + kvm_riscv_vcpu_trap_redirect(vcpu, ut_scause, ct->sepc); > + return 1; > + } > + > + /* Decode length of MMIO and shift */ > + if ((insn & INSN_MASK_LW) == INSN_MATCH_LW) { > + len = 4; > + shift = 8 * (sizeof(ulong) - len); > + } else if ((insn & INSN_MASK_LB) == INSN_MATCH_LB) { > + len = 1; > + shift = 8 * (sizeof(ulong) - len); > + } else if ((insn & INSN_MASK_LBU) == INSN_MATCH_LBU) { > + len = 1; > + shift = 8 * (sizeof(ulong) - len); > +#ifdef CONFIG_64BIT > + } else if ((insn & INSN_MASK_LD) == INSN_MATCH_LD) { > + len = 8; > + shift = 8 * (sizeof(ulong) - len); > + } else if ((insn & INSN_MASK_LWU) == INSN_MATCH_LWU) { > + len = 4; > +#endif > + } else if ((insn & INSN_MASK_LH) == INSN_MATCH_LH) { > + len = 2; > + shift = 8 * (sizeof(ulong) - len); > + } else if ((insn & INSN_MASK_LHU) == INSN_MATCH_LHU) { > + len = 2; > +#ifdef CONFIG_64BIT > + } else if ((insn & INSN_MASK_C_LD) == INSN_MATCH_C_LD) { > + len = 8; > + shift = 8 * (sizeof(ulong) - len); > + insn = RVC_RS2S(insn) << SH_RD; > + } else if ((insn & INSN_MASK_C_LDSP) == INSN_MATCH_C_LDSP && > + ((insn >> SH_RD) & 0x1f)) { > + len = 8; > + shift = 8 * (sizeof(ulong) - len); > +#endif > + } else if ((insn & INSN_MASK_C_LW) == INSN_MATCH_C_LW) { > + len = 4; > + shift = 8 * (sizeof(ulong) - len); > + insn = RVC_RS2S(insn) << SH_RD; > + } else if ((insn & INSN_MASK_C_LWSP) == INSN_MATCH_C_LWSP && > + ((insn >> SH_RD) & 0x1f)) { > + len = 4; > + shift = 8 * (sizeof(ulong) - len); > + } else { > + return -ENOTSUPP; > + } > + > + /* Fault address should be aligned to length of MMIO */ > + if (fault_addr & (len - 1)) > + return -EIO; > + > + /* Save instruction decode info */ > + vcpu->arch.mmio_decode.insn = insn; > + vcpu->arch.mmio_decode.shift = shift; > + vcpu->arch.mmio_decode.len = len; > + vcpu->arch.mmio_decode.return_handled = 0; > + > + /* Exit to userspace for MMIO emulation */ > + vcpu->stat.mmio_exit_user++; > + run->exit_reason = KVM_EXIT_MMIO; > + run->mmio.is_write = false; > + run->mmio.phys_addr = fault_addr; > + run->mmio.len = len; > + > + return 0; > +} > + > +static int emulate_store(struct kvm_vcpu *vcpu, struct kvm_run *run, > + unsigned long fault_addr) > +{ > + u8 data8; > + u16 data16; > + u32 data32; > + u64 data64; > + ulong data; > + int len = 0; > + unsigned long ut_scause = 0; > + struct kvm_cpu_context *ct = &vcpu->arch.guest_context; > + ulong insn = kvm_riscv_vcpu_unpriv_read(vcpu, true, ct->sepc, > + &ut_scause); > + > + /* Redirect trap if we failed to read instruction */ > + if (ut_scause) { > + if (ut_scause == EXC_LOAD_PAGE_FAULT) > + ut_scause = EXC_INST_PAGE_FAULT; > + kvm_riscv_vcpu_trap_redirect(vcpu, ut_scause, ct->sepc); > + return 1; > + } > + > + data = GET_RS2(insn, &vcpu->arch.guest_context); > + data8 = data16 = data32 = data64 = data; > + > + if ((insn & INSN_MASK_SW) == INSN_MATCH_SW) { > + len = 4; > + } else if ((insn & INSN_MASK_SB) == INSN_MATCH_SB) { > + len = 1; > +#ifdef CONFIG_64BIT > + } else if ((insn & INSN_MASK_SD) == INSN_MATCH_SD) { > + len = 8; > +#endif > + } else if ((insn & INSN_MASK_SH) == INSN_MATCH_SH) { > + len = 2; > +#ifdef CONFIG_64BIT > + } else if ((insn & INSN_MASK_C_SD) == INSN_MATCH_C_SD) { > + len = 8; > + data64 = GET_RS2S(insn, &vcpu->arch.guest_context); > + } else if ((insn & INSN_MASK_C_SDSP) == INSN_MATCH_C_SDSP && > + ((insn >> SH_RD) & 0x1f)) { > + len = 8; > + data64 = GET_RS2C(insn, &vcpu->arch.guest_context); > +#endif > + } else if ((insn & INSN_MASK_C_SW) == INSN_MATCH_C_SW) { > + len = 4; > + data32 = GET_RS2S(insn, &vcpu->arch.guest_context); > + } else if ((insn & INSN_MASK_C_SWSP) == INSN_MATCH_C_SWSP && > + ((insn >> SH_RD) & 0x1f)) { > + len = 4; > + data32 = GET_RS2C(insn, &vcpu->arch.guest_context); > + } else { > + return -ENOTSUPP; > + } > + > + /* Fault address should be aligned to length of MMIO */ > + if (fault_addr & (len - 1)) > + return -EIO; > + > + /* Save instruction decode info */ > + vcpu->arch.mmio_decode.insn = insn; > + vcpu->arch.mmio_decode.shift = 0; > + vcpu->arch.mmio_decode.len = len; > + vcpu->arch.mmio_decode.return_handled = 0; > + > + /* Copy data to kvm_run instance */ > + switch (len) { > + case 1: > + *((u8 *)run->mmio.data) = data8; > + break; > + case 2: > + *((u16 *)run->mmio.data) = data16; > + break; > + case 4: > + *((u32 *)run->mmio.data) = data32; > + break; > + case 8: > + *((u64 *)run->mmio.data) = data64; > + break; > + default: > + return -ENOTSUPP; > + }; > + > + /* Exit to userspace for MMIO emulation */ > + vcpu->stat.mmio_exit_user++; > + run->exit_reason = KVM_EXIT_MMIO; > + run->mmio.is_write = true; > + run->mmio.phys_addr = fault_addr; > + run->mmio.len = len; > + > + return 0; > +} > + > +static int stage2_page_fault(struct kvm_vcpu *vcpu, struct kvm_run *run, > + unsigned long scause, unsigned long stval) > +{ > + struct kvm_memory_slot *memslot; > + unsigned long hva; > + bool writable; > + gfn_t gfn; > + int ret; > + > + gfn = stval >> PAGE_SHIFT; > + memslot = gfn_to_memslot(vcpu->kvm, gfn); > + hva = gfn_to_hva_memslot_prot(memslot, gfn, &writable); > + > + if (kvm_is_error_hva(hva) || > + (scause == EXC_STORE_PAGE_FAULT && !writable)) { > + switch (scause) { > + case EXC_LOAD_PAGE_FAULT: > + return emulate_load(vcpu, run, stval); > + case EXC_STORE_PAGE_FAULT: > + return emulate_store(vcpu, run, stval); > + default: > + return -ENOTSUPP; > + }; > + } > + > + ret = kvm_riscv_stage2_map(vcpu, stval, hva, > + (scause == EXC_STORE_PAGE_FAULT) ? true : false); > + if (ret < 0) > + return ret; > + > + return 1; > +} > + > +#define STR(x) XSTR(x) > +#define XSTR(x) #x > + > +/** > + * kvm_riscv_vcpu_unpriv_read -- Read machine word from Guest memory > + * > + * @vcpu: The VCPU pointer > + * @read_insn: Flag representing whether we are reading instruction > + * @guest_addr: Guest address to read > + * @trap_scause: Output pointer for unprivilege trap cause > + */ > +unsigned long kvm_riscv_vcpu_unpriv_read(struct kvm_vcpu *vcpu, > + bool read_insn, > + unsigned long guest_addr, > + unsigned long *trap_scause) > +{ > + register unsigned long tscause asm("a0"); > + register unsigned long val asm("a1"); > + register unsigned long addr asm("a2") = guest_addr; > + unsigned long guest_sstatus = > + vcpu->arch.guest_context.sstatus | ((read_insn) ? SR_MXR : 0); > + unsigned long guest_hstatus = > + vcpu->arch.guest_context.hstatus | HSTATUS_SPRV; > + unsigned long old_stvec, tmp; > + > + BUG_ON(guest_sstatus & SR_SIE); > + > + guest_sstatus = csr_swap(CSR_SSTATUS, guest_sstatus); > + old_stvec = csr_swap(CSR_STVEC, (ulong)&__kvm_riscv_unpriv_trap); > + > + if (read_insn) { > + asm volatile ("\n" > + "csrrw %[hstatus], " STR(CSR_HSTATUS) ", %[hstatus]\n" > + "li %[tscause], 0\n" > + "lhu %[val], (%[addr])\n" > + "andi %[tmp], %[val], 3\n" > + "addi %[tmp], %[tmp], -3\n" > + "bne %[tmp], zero, 2f\n" > + "lhu %[tmp], 2(%[addr])\n" > + "sll %[tmp], %[tmp], 16\n" > + "add %[val], %[val], %[tmp]\n" > + "2: csrw " STR(CSR_HSTATUS) ", %[hstatus]" > + : [hstatus] "+&r"(guest_hstatus), [val] "=&r" (val), > + [tmp] "=&r" (tmp), [tscause] "+&r" (tscause) > + : [addr] "r" (addr)); > + } else { > + asm volatile ("\n" > + "csrrw %[hstatus], " STR(CSR_HSTATUS) ", %[hstatus]\n" > + "li %[tscause], 0\n" > + ".option push\n" > + ".option norvc\n" > +#ifdef CONFIG_64BIT > + "ld %[val], (%[addr])\n" > +#else > + "lw %[val], (%[addr])\n" > +#endif > + ".option pop\n" > + "csrw " STR(CSR_HSTATUS) ", %[hstatus]" > + : [hstatus] "+&r"(guest_hstatus), > + [val] "=&r" (val), [tscause] "+&r" (tscause) > + : [addr] "r" (addr)); > + } > + > + csr_write(CSR_STVEC, old_stvec); > + csr_write(CSR_SSTATUS, guest_sstatus); > + > + *trap_scause = tscause; > + > + return val; > +} > + > +/** > + * kvm_riscv_vcpu_trap_redirect -- Redirect trap to Guest > + * > + * @vcpu: The VCPU pointer > + * @scause: Trap exception cause > + * @stval: Trap value > + */ > +void kvm_riscv_vcpu_trap_redirect(struct kvm_vcpu *vcpu, > + unsigned long scause, unsigned long stval) > +{ > + unsigned long vsstatus = csr_read(CSR_VSSTATUS); > + > + /* Change Guest SSTATUS.SPP bit */ > + vsstatus &= ~SR_SPP; > + if (vcpu->arch.guest_context.sstatus & SR_SPP) > + vsstatus |= SR_SPP; > + > + /* Change Guest SSTATUS.SPIE bit */ > + vsstatus &= ~SR_SPIE; > + if (vsstatus & SR_SIE) > + vsstatus |= SR_SPIE; > + > + /* Clear Guest SSTATUS.SIE bit */ > + vsstatus &= ~SR_SIE; > + > + /* Update Guest SSTATUS */ > + csr_write(CSR_VSSTATUS, vsstatus); > + > + /* Update Guest SCAUSE, STVAL, and SEPC */ > + csr_write(CSR_VSCAUSE, scause); > + csr_write(CSR_VSTVAL, stval); > + csr_write(CSR_VSEPC, vcpu->arch.guest_context.sepc); > + > + /* Set Guest PC to Guest exception vector */ > + vcpu->arch.guest_context.sepc = csr_read(CSR_VSTVEC); > +} > > /** > * kvm_riscv_vcpu_mmio_return -- Handle MMIO loads after user space emulation > @@ -19,7 +440,54 @@ > */ > int kvm_riscv_vcpu_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run) > { > - /* TODO: */ > + u8 data8; > + u16 data16; > + u32 data32; > + u64 data64; > + ulong insn; > + int len, shift; > + > + if (vcpu->arch.mmio_decode.return_handled) > + return 0; > + > + vcpu->arch.mmio_decode.return_handled = 1; > + insn = vcpu->arch.mmio_decode.insn; > + > + if (run->mmio.is_write) > + goto done; > + > + len = vcpu->arch.mmio_decode.len; > + shift = vcpu->arch.mmio_decode.shift; > + > + switch (len) { > + case 1: > + data8 = *((u8 *)run->mmio.data); > + SET_RD(insn, &vcpu->arch.guest_context, > + (ulong)data8 << shift >> shift); > + break; > + case 2: > + data16 = *((u16 *)run->mmio.data); > + SET_RD(insn, &vcpu->arch.guest_context, > + (ulong)data16 << shift >> shift); > + break; > + case 4: > + data32 = *((u32 *)run->mmio.data); > + SET_RD(insn, &vcpu->arch.guest_context, > + (ulong)data32 << shift >> shift); > + break; > + case 8: > + data64 = *((u64 *)run->mmio.data); > + SET_RD(insn, &vcpu->arch.guest_context, > + (ulong)data64 << shift >> shift); > + break; > + default: > + return -ENOTSUPP; > + }; > + > +done: > + /* Move to next instruction */ > + vcpu->arch.guest_context.sepc += INSN_LEN(insn); > + > return 0; > } > > @@ -30,6 +498,37 @@ int kvm_riscv_vcpu_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run) > int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run, > unsigned long scause, unsigned long stval) > { > - /* TODO: */ > - return 0; > + int ret; > + > + /* If we got host interrupt then do nothing */ > + if (scause & SCAUSE_IRQ_FLAG) > + return 1; > + > + /* Handle guest traps */ > + ret = -EFAULT; > + run->exit_reason = KVM_EXIT_UNKNOWN; > + switch (scause) { > + case EXC_INST_PAGE_FAULT: > + case EXC_LOAD_PAGE_FAULT: > + case EXC_STORE_PAGE_FAULT: > + if ((vcpu->arch.guest_context.hstatus & HSTATUS_SPV) && > + (vcpu->arch.guest_context.hstatus & HSTATUS_STL)) > + ret = stage2_page_fault(vcpu, run, scause, stval); > + break; > + default: > + break; > + }; > + > + /* Print details in-case of error */ > + if (ret < 0) { > + kvm_err("VCPU exit error %d\n", ret); > + kvm_err("SEPC=0x%lx SSTATUS=0x%lx HSTATUS=0x%lx\n", > + vcpu->arch.guest_context.sepc, > + vcpu->arch.guest_context.sstatus, > + vcpu->arch.guest_context.hstatus); > + kvm_err("SCAUSE=0x%lx STVAL=0x%lx\n", > + scause, stval); > + } > + > + return ret; > } > diff --git a/arch/riscv/kvm/vcpu_switch.S b/arch/riscv/kvm/vcpu_switch.S > index e1a17df1b379..04b318b9eef8 100644 > --- a/arch/riscv/kvm/vcpu_switch.S > +++ b/arch/riscv/kvm/vcpu_switch.S > @@ -192,3 +192,17 @@ __kvm_switch_return: > /* Return to C code */ > ret > ENDPROC(__kvm_riscv_switch_to) > + > +ENTRY(__kvm_riscv_unpriv_trap) > + /* > + * We assume that faulting unpriv load/store instruction is > + * is 4-byte long and blindly increment SEPC by 4. > + * > + * The trap exception cause will be saved in 'A0' register. > + */ > + csrr a0, CSR_SEPC > + addi a0, a0, 4 > + csrw CSR_SEPC, a0 > + csrr a0, CSR_SCAUSE > + sret > +ENDPROC(__kvm_riscv_unpriv_trap) >