RE: [PATCH RFC v6 08/12] target/riscv: Handle KVM_EXIT_RISCV_SBI exit

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> -----Original Message-----
> From: Qemu-riscv
> [mailto:qemu-riscv-bounces+jiangyifei=huawei.com@xxxxxxxxxx] On Behalf Of
> Alistair Francis
> Sent: Thursday, August 19, 2021 2:14 PM
> To: Jiangyifei <jiangyifei@xxxxxxxxxx>
> Cc: Anup Patel <anup.patel@xxxxxxx>; open list:RISC-V
> <qemu-riscv@xxxxxxxxxx>; open list:Overall <kvm@xxxxxxxxxxxxxxx>;
> limingwang (A) <limingwang@xxxxxxxxxx>; libvir-list@xxxxxxxxxx; Bin Meng
> <bin.meng@xxxxxxxxxxxxx>; qemu-devel@xxxxxxxxxx Developers
> <qemu-devel@xxxxxxxxxx>; Alistair Francis <Alistair.Francis@xxxxxxx>;
> kvm-riscv@xxxxxxxxxxxxxxxxxxx; Wanghaibin (D)
> <wanghaibin.wang@xxxxxxxxxx>; Fanliang (EulerOS) <fanliang@xxxxxxxxxx>;
> Palmer Dabbelt <palmer@xxxxxxxxxxx>; Wubin (H) <wu.wubin@xxxxxxxxxx>
> Subject: Re: [PATCH RFC v6 08/12] target/riscv: Handle KVM_EXIT_RISCV_SBI
> exit
> 
> On Tue, Aug 17, 2021 at 1:25 PM Yifei Jiang <jiangyifei@xxxxxxxxxx> wrote:
> >
> > Use char-fe to handle console sbi call, which implement early console
> > io while apply 'earlycon=sbi' into kernel parameters.
> >
> > Signed-off-by: Yifei Jiang <jiangyifei@xxxxxxxxxx>
> > Signed-off-by: Mingwang Li <limingwang@xxxxxxxxxx>
> > ---
> >  target/riscv/kvm.c                 | 42 ++++++++++++++++-
> >  target/riscv/sbi_ecall_interface.h | 72
> > ++++++++++++++++++++++++++++++
> >  2 files changed, 113 insertions(+), 1 deletion(-)  create mode 100644
> > target/riscv/sbi_ecall_interface.h
> >
> > diff --git a/target/riscv/kvm.c b/target/riscv/kvm.c index
> > bc9cb5d8f9..a68f31c2f3 100644
> > --- a/target/riscv/kvm.c
> > +++ b/target/riscv/kvm.c
> > @@ -38,6 +38,8 @@
> >  #include "qemu/log.h"
> >  #include "hw/loader.h"
> >  #include "kvm_riscv.h"
> > +#include "sbi_ecall_interface.h"
> > +#include "chardev/char-fe.h"
> >
> >  static uint64_t kvm_riscv_reg_id(CPURISCVState *env, uint64_t type,
> > uint64_t idx)  { @@ -435,9 +437,47 @@ bool
> > kvm_arch_stop_on_emulation_error(CPUState *cs)
> >      return true;
> >  }
> >
> > +static int kvm_riscv_handle_sbi(struct kvm_run *run) {
> > +    int ret = 0;
> > +    unsigned char ch;
> > +    switch (run->riscv_sbi.extension_id) {
> > +    case SBI_EXT_0_1_CONSOLE_PUTCHAR:
> > +        ch = run->riscv_sbi.args[0];
> > +        qemu_chr_fe_write(serial_hd(0)->be, &ch, sizeof(ch));
> > +        break;
> > +    case SBI_EXT_0_1_CONSOLE_GETCHAR:
> > +        ret = qemu_chr_fe_read_all(serial_hd(0)->be, &ch, sizeof(ch));
> > +        if (ret == sizeof(ch)) {
> > +            run->riscv_sbi.args[0] = ch;
> > +        } else {
> > +            run->riscv_sbi.args[0] = -1;
> > +        }
> > +        break;
> 
> These have been deprecated (see
> https://github.com/riscv/riscv-sbi-doc/blob/master/riscv-sbi.adoc#4-legacy-ext
> ensions-eids-0x00---0x0f),
> is it even worth supporting them?
> 

Yes. The legacy console SBI functions (sbi_console_getchar() and sbi_console_putchar())
are expected to be deprecated.

However, the linux kernel still uses these sbi call interfaces, so they are retained here.
If the linux kernel doesn't use these interfaces, we will remove them.

Yifei

> > +    default:
> > +        qemu_log_mask(LOG_UNIMP,
> > +                      "%s: un-handled SBI EXIT, specific reasons
> is %lu\n",
> > +                      __func__, run->riscv_sbi.extension_id);
> > +        ret = -1;
> > +        break;
> > +    }
> > +    return ret;
> > +}
> > +
> >  int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run)  {
> > -    return 0;
> > +    int ret = 0;
> > +    switch (run->exit_reason) {
> > +    case KVM_EXIT_RISCV_SBI:
> > +        ret = kvm_riscv_handle_sbi(run);
> > +        break;
> > +    default:
> > +        qemu_log_mask(LOG_UNIMP, "%s: un-handled exit reason %d\n",
> > +                      __func__, run->exit_reason);
> > +        ret = -1;
> > +        break;
> > +    }
> > +    return ret;
> >  }
> >
> >  void kvm_riscv_reset_vcpu(RISCVCPU *cpu) diff --git
> > a/target/riscv/sbi_ecall_interface.h
> > b/target/riscv/sbi_ecall_interface.h
> > new file mode 100644
> > index 0000000000..fb1a3fa8f2
> > --- /dev/null
> > +++ b/target/riscv/sbi_ecall_interface.h
> > @@ -0,0 +1,72 @@
> > +/*
> > + * SPDX-License-Identifier: BSD-2-Clause
> > + *
> > + * Copyright (c) 2019 Western Digital Corporation or its affiliates.
> > + *
> > + * Authors:
> > + *   Anup Patel <anup.patel@xxxxxxx>
> > + */
> > +
> > +#ifndef __SBI_ECALL_INTERFACE_H__
> > +#define __SBI_ECALL_INTERFACE_H__
> > +
> > +/* clang-format off */
> > +
> > +/* SBI Extension IDs */
> > +#define SBI_EXT_0_1_SET_TIMER           0x0
> > +#define SBI_EXT_0_1_CONSOLE_PUTCHAR     0x1
> > +#define SBI_EXT_0_1_CONSOLE_GETCHAR     0x2
> > +#define SBI_EXT_0_1_CLEAR_IPI           0x3
> > +#define SBI_EXT_0_1_SEND_IPI            0x4
> > +#define SBI_EXT_0_1_REMOTE_FENCE_I      0x5
> > +#define SBI_EXT_0_1_REMOTE_SFENCE_VMA   0x6
> > +#define SBI_EXT_0_1_REMOTE_SFENCE_VMA_ASID 0x7
> > +#define SBI_EXT_0_1_SHUTDOWN            0x8
> > +#define SBI_EXT_BASE                    0x10
> > +#define SBI_EXT_TIME                    0x54494D45
> > +#define SBI_EXT_IPI                     0x735049
> > +#define SBI_EXT_RFENCE                  0x52464E43
> > +#define SBI_EXT_HSM                     0x48534D
> > +
> > +/* SBI function IDs for BASE extension*/
> > +#define SBI_EXT_BASE_GET_SPEC_VERSION   0x0
> > +#define SBI_EXT_BASE_GET_IMP_ID         0x1
> > +#define SBI_EXT_BASE_GET_IMP_VERSION    0x2
> > +#define SBI_EXT_BASE_PROBE_EXT          0x3
> > +#define SBI_EXT_BASE_GET_MVENDORID      0x4
> > +#define SBI_EXT_BASE_GET_MARCHID        0x5
> > +#define SBI_EXT_BASE_GET_MIMPID         0x6
> > +
> > +/* SBI function IDs for TIME extension*/
> > +#define SBI_EXT_TIME_SET_TIMER          0x0
> > +
> > +/* SBI function IDs for IPI extension*/
> > +#define SBI_EXT_IPI_SEND_IPI            0x0
> > +
> > +/* SBI function IDs for RFENCE extension*/
> > +#define SBI_EXT_RFENCE_REMOTE_FENCE_I       0x0
> > +#define SBI_EXT_RFENCE_REMOTE_SFENCE_VMA    0x1
> > +#define SBI_EXT_RFENCE_REMOTE_SFENCE_VMA_ASID  0x2
> > +#define SBI_EXT_RFENCE_REMOTE_HFENCE_GVMA   0x3
> > +#define SBI_EXT_RFENCE_REMOTE_HFENCE_GVMA_VMID 0x4
> > +#define SBI_EXT_RFENCE_REMOTE_HFENCE_VVMA   0x5
> > +#define SBI_EXT_RFENCE_REMOTE_HFENCE_VVMA_ASID 0x6
> > +
> > +/* SBI function IDs for HSM extension */
> > +#define SBI_EXT_HSM_HART_START          0x0
> > +#define SBI_EXT_HSM_HART_STOP           0x1
> > +#define SBI_EXT_HSM_HART_GET_STATUS     0x2
> > +
> > +#define SBI_HSM_HART_STATUS_STARTED     0x0
> > +#define SBI_HSM_HART_STATUS_STOPPED     0x1
> > +#define SBI_HSM_HART_STATUS_START_PENDING   0x2
> > +#define SBI_HSM_HART_STATUS_STOP_PENDING    0x3
> > +
> > +#define SBI_SPEC_VERSION_MAJOR_OFFSET   24
> > +#define SBI_SPEC_VERSION_MAJOR_MASK     0x7f
> > +#define SBI_SPEC_VERSION_MINOR_MASK     0xffffff
> > +#define SBI_EXT_VENDOR_START            0x09000000
> > +#define SBI_EXT_VENDOR_END              0x09FFFFFF
> > +/* clang-format on */
> > +
> > +#endif
> > --
> > 2.19.1
> >
> >





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