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


From: Anup Patel
Subject: Re: [PATCH RFC 8/9] target/riscv: Handler KVM_EXIT_RISCV_SBI exit
Date: Tue, 31 Mar 2020 15:21:23 +0530

On Tue, Mar 31, 2020 at 2:56 PM Jiangyifei <address@hidden> wrote:
>
>
> > -----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.

Ahh, yes I forgot about KVM_SYSTEM_EVENT_SHUTDOWN

No need to handle SBI_EXT_0_1_SHUTDOWN here.

Regards,
Anup

>
> >
> > > +    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



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