RE: [PATCH RFC 8/9] target/riscv: Handler KVM_EXIT_RISCV_SBI exit

[Jiangyifei]

> -----Original Message-----
> From: Anup Patel [mailto:address@hidden]
> Sent: Tuesday, March 31, 2020 1:17 PM
> To: Jiangyifei <address@hidden>
> Cc: QEMU Developers <address@hidden>; open list:RISC-V <qemu-
> address@hidden>; Anup Patel <address@hidden>; Zhanghailiang
> <address@hidden>; Sagar Karandikar
> <address@hidden>; Bastian Koppelmann <address@hidden-
> paderborn.de>; Zhangxiaofeng (F) <address@hidden>;
> Alistair Francis <address@hidden>; yinyipeng
> <address@hidden>; Palmer Dabbelt <address@hidden>;
> dengkai (A) <address@hidden>
> Subject: Re: [PATCH RFC 8/9] target/riscv: Handler KVM_EXIT_RISCV_SBI exit
> 
> On Fri, Mar 13, 2020 at 9:23 AM Yifei Jiang <address@hidden> wrote:
> >
> > Use char-fe handler console sbi call, which implement early console io
> > while apply 'earlycon=sbi' into kernel parameters.
> >
> > Signed-off-by: Yifei Jiang <address@hidden>
> > Signed-off-by: Yipeng Yin <address@hidden>
> > ---
> >  target/riscv/kvm.c | 54
> > +++++++++++++++++++++++++++++++++++++++++++++-
> >  1 file changed, 53 insertions(+), 1 deletion(-)
> >
> > diff --git a/target/riscv/kvm.c b/target/riscv/kvm.c index
> > 0f429fd802..1df70fbb29 100644
> > --- a/target/riscv/kvm.c
> > +++ b/target/riscv/kvm.c
> > @@ -38,6 +38,7 @@
> >  #include "qemu/log.h"
> >  #include "hw/loader.h"
> >  #include "kvm_riscv.h"
> > +#include "chardev/char-fe.h"
> >
> >  static __u64 kvm_riscv_reg_id(__u64 type, __u64 idx)  { @@ -61,6
> > +62,19 @@ static __u64 kvm_riscv_reg_id(__u64 type, __u64 idx)
> >
> >  #define RISCV_FP_D_REG(idx)  kvm_riscv_reg_id(KVM_REG_RISCV_FP_D,
> > idx)
> >
> > +enum sbi_ext_id {
> > +    SBI_EXT_0_1_SET_TIMER = 0x0,
> > +    SBI_EXT_0_1_CONSOLE_PUTCHAR = 0x1,
> > +    SBI_EXT_0_1_CONSOLE_GETCHAR = 0x2,
> > +    SBI_EXT_0_1_CLEAR_IPI = 0x3,
> > +    SBI_EXT_0_1_SEND_IPI = 0x4,
> > +    SBI_EXT_0_1_REMOTE_FENCE_I = 0x5,
> > +    SBI_EXT_0_1_REMOTE_SFENCE_VMA = 0x6,
> > +    SBI_EXT_0_1_REMOTE_SFENCE_VMA_ASID = 0x7,
> > +    SBI_EXT_0_1_SHUTDOWN = 0x8,
> > +    SBI_EXT_BASE = 0x10,
> > +};
> > +
> 
> Please add separate SBI ecall interface header (similar to OpenSBI).
> This header will only have SBI spec related defines.
> 
> Refer,
> https://github.com/riscv/opensbi/blob/master/include/sbi/sbi_ecall_interfa
> ce.h

Yes, thanks for your review. I'll update it at next series after you review 
this series all.

> 
> >  static int kvm_riscv_get_regs_core(CPUState *cs)  {
> >      int ret = 0;
> > @@ -423,9 +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;
> 
> Please emulate SBI v0.1 Shutdown call as well.

It seems that there is no need for emulating SHUTDOWN call at QEMU.
SBI_EXT_0_1_SHUTDOWN is redirect to KVM_SYSTEM_EVENT_SHUTDOWN in KVM,
which is handled by common kvm-exit handler in QEMU.
And, It is normal to perform `poweroff` in the virtual machine.

> 
> > +    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)
> > --
> > 2.19.1
> >
> >
> >
> 
> Regards,
> Anup

Best regards,
Yifei Jiang