Re: [PATCH v6 10/21] RISC-V: KVM: Handle MMIO exits for VCPU
From: Anup Patel
Date: Tue Sep 03 2019 - 05:33:45 EST
On Thu, Aug 29, 2019 at 7:26 PM Anup Patel <Anup.Patel@xxxxxxx> 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>
> ---
> arch/riscv/include/asm/kvm_host.h | 20 ++
> arch/riscv/kvm/mmu.c | 7 +
> arch/riscv/kvm/vcpu_exit.c | 504 +++++++++++++++++++++++++++++-
> arch/riscv/kvm/vcpu_switch.S | 9 +
> 4 files changed, 537 insertions(+), 3 deletions(-)
>
> diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
> index 18f1097f1d8d..36974001433f 100644
> --- a/arch/riscv/include/asm/kvm_host.h
> +++ b/arch/riscv/include/asm/kvm_host.h
> @@ -53,6 +53,12 @@ struct kvm_arch {
> phys_addr_t pgd_phys;
> };
>
> +struct kvm_mmio_decode {
> + unsigned long insn;
> + int len;
> + int shift;
> +};
> +
> struct kvm_cpu_context {
> unsigned long zero;
> unsigned long ra;
> @@ -141,6 +147,9 @@ 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 +169,22 @@ 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,
> + unsigned long *trap_stval);
> +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..700d8158e55b 100644
> --- a/arch/riscv/kvm/vcpu_exit.c
> +++ b/arch/riscv/kvm/vcpu_exit.c
> @@ -6,9 +6,433 @@
> * 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_LEN(insn) ((((insn) & 0x3) < 0x3) ? 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, ut_stval = 0;
> + struct kvm_cpu_context *ct = &vcpu->arch.guest_context;
> + ulong insn = kvm_riscv_vcpu_unpriv_read(vcpu, true, ct->sepc,
> + &ut_scause, &ut_stval);
> +
> + /* Redirect trap if we failed to read instruction */
> + if (ut_scause) {
> + kvm_riscv_vcpu_trap_redirect(vcpu, ut_scause, ut_stval);
> + 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_RISCV_ISA_C
> +#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);
> +#endif
> + } 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;
> +
> + /* 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, ut_stval = 0;
> + struct kvm_cpu_context *ct = &vcpu->arch.guest_context;
> + ulong insn = kvm_riscv_vcpu_unpriv_read(vcpu, true, ct->sepc,
> + &ut_scause, &ut_stval);
> +
> + /* Redirect trap if we failed to read instruction */
> + if (ut_scause) {
> + kvm_riscv_vcpu_trap_redirect(vcpu, ut_scause, ut_stval);
> + 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_RISCV_ISA_C
> +#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);
> +#endif
> + } 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;
> +
> + /* 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
> + * @trap_stval: Output pointer for unprivilege trap value
> + */
> +unsigned long kvm_riscv_vcpu_unpriv_read(struct kvm_vcpu *vcpu,
> + bool read_insn,
> + unsigned long guest_addr,
> + unsigned long *trap_scause,
> + unsigned long *trap_stval)
This function can be further improved by dropping trap_stval argument
because all callers of this function always know the faulting address.
> +{
> + register unsigned long tilen asm("a0");
> + register unsigned long tscause asm("a1");
> + register unsigned long tstval asm("a2");
> + register unsigned long val asm("a3");
> + register unsigned long addr asm("a4") = guest_addr;
> + unsigned long guest_sstatus = vcpu->arch.guest_context.sstatus;
> + unsigned long guest_hstatus = vcpu->arch.guest_context.hstatus;
> + unsigned long guest_vsstatus, old_stvec, tmp;
> +
> + guest_sstatus = csr_swap(CSR_SSTATUS, guest_sstatus | SR_MXR);
> + old_stvec = csr_swap(CSR_STVEC, (ulong)&__kvm_riscv_unpriv_trap);
> + guest_vsstatus = csr_read_set(CSR_VSSTATUS, SR_MXR);
> + guest_hstatus = csr_swap(CSR_HSTATUS, guest_hstatus | HSTATUS_SPRV);
> +
> + if (read_insn) {
> + asm volatile ("li %[tilen], 4\n"
> + "li %[tscause], 0\n"
> + "li %[tstval], 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:"
> + : [val] "=&r" (val), [tmp] "=&r" (tmp), [tilen] "+&r" (tilen),
> + [tscause] "+&r" (tscause), [tstval] "+&r" (tstval)
> + : [addr] "r" (addr));
> + } else {
> + asm volatile ("\n"
> +#ifndef CONFIG_RISCV_ISA_C
> + "li %[tilen], 4\n"
> +#else
> + "li %[tilen], 2\n"
> +#endif
> + "li %[tscause], 0\n"
> + "li %[tstval], 0\n"
> +#ifdef CONFIG_64BIT
> + "ld %[val], (%[addr])"
> +#else
> + "lw %[val], (%[addr])"
> +#endif
> + : [val] "=&r" (val), [tilen] "+&r" (tilen),
> + [tscause] "+&r" (tscause), [tstval] "+&r" (tstval)
> + : [addr] "r" (addr));
> + }
> +
> + csr_write(CSR_HSTATUS, guest_hstatus);
> + csr_write(CSR_VSSTATUS, guest_vsstatus);
> + csr_write(CSR_STVEC, old_stvec);
> + csr_write(CSR_SSTATUS, guest_sstatus);
> +
> + if (read_insn && tscause == EXC_LOAD_PAGE_FAULT)
> + tscause = EXC_INST_PAGE_FAULT;
Another improvement is to move this "if" statement to callers
of this function with read_insn = true so that we don't do unnecessary
comparison for most likely cases where tscause == 0.
I will address this in v7.
Regards,
Anup
> +
> + *trap_scause = tscause;
> + *trap_stval = tstval;
> +
> + 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 +443,50 @@
> */
> 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;
> +
> + 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 +497,37 @@ 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..4598f33b2139 100644
> --- a/arch/riscv/kvm/vcpu_switch.S
> +++ b/arch/riscv/kvm/vcpu_switch.S
> @@ -192,3 +192,12 @@ __kvm_switch_return:
> /* Return to C code */
> ret
> ENDPROC(__kvm_riscv_switch_to)
> +
> +ENTRY(__kvm_riscv_unpriv_trap)
> + csrr a1, CSR_SEPC
> + add a1, a1, a0
> + csrw CSR_SEPC, a1
> + csrr a1, CSR_SCAUSE
> + csrr a2, CSR_STVAL
> + sret
> +ENDPROC(__kvm_riscv_unpriv_trap)
> --
> 2.17.1
>