Re: [XEN PATCH v4] x86/monitor: Add new monitor event to catch I/O instructions

[Jan Beulich <jbeulich@xxxxxxxx>]

On 20.03.2023 22:56, Dmitry Isaykin wrote:
> Adds monitor support for I/O instructions.
> 
> Signed-off-by: Dmitry Isaykin <isaikin-dmitry@xxxxxxxxx>
> Signed-off-by: Anton Belousov <abelousov@xxxxxxxxxxxxxx>

LGTM now FWIW, but this part ...

> --- a/xen/arch/x86/hvm/vmx/vmx.c
> +++ b/xen/arch/x86/hvm/vmx/vmx.c
> @@ -4560,8 +4560,24 @@ void vmx_vmexit_handler(struct cpu_user_regs *regs)
>          break;
>  
>      case EXIT_REASON_IO_INSTRUCTION:
> +    {
> +        unsigned int port, bytes;
> +        bool in, str;
> +        int rc;
> +
>          __vmread(EXIT_QUALIFICATION, &exit_qualification);
> -        if ( exit_qualification & 0x10 )
> +
> +        port = (exit_qualification >> 16) & 0xFFFF;
> +        bytes = (exit_qualification & 0x07) + 1;
> +        in = (exit_qualification & 0x08);
> +        str = (exit_qualification & 0x10);
> +        rc = hvm_monitor_io(port, bytes, in, str);
> +        if ( rc < 0 )
> +            goto exit_and_crash;
> +        if ( rc )
> +            break;
> +
> +        if ( str )
>          {
>              /* INS, OUTS */
>              if ( !hvm_emulate_one_insn(x86_insn_is_portio, "port I/O") )
> @@ -4570,13 +4586,11 @@ void vmx_vmexit_handler(struct cpu_user_regs *regs)
>          else
>          {
>              /* IN, OUT */
> -            uint16_t port = (exit_qualification >> 16) & 0xFFFF;
> -            int bytes = (exit_qualification & 0x07) + 1;
> -            int dir = (exit_qualification & 0x08) ? IOREQ_READ : IOREQ_WRITE;
> -            if ( handle_pio(port, bytes, dir) )
> +            if ( handle_pio(port, bytes, in ? IOREQ_READ : IOREQ_WRITE) )
>                  update_guest_eip(); /* Safe: IN, OUT */
>          }
>          break;
> +    }

... would preferably be re-based over Andrew's change to use bitfields here
as well (just like was already done by him for SVM).

Jan