Re: [Xen-devel] [PATCH 3/6] x86: Handle the Xen MSRs via the new guest_{rd, wr}msr() infrastructure

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 26.02.18 at 18:35, <andrew.cooper3@xxxxxxxxxx> wrote:
> --- a/xen/arch/x86/msr.c
> +++ b/xen/arch/x86/msr.c
> @@ -183,6 +183,10 @@ int guest_rdmsr(const struct vcpu *v, uint32_t msr, 
> uint64_t *val)
>          }
>  
>          /* Fallthrough. */
> +    case 0x40000200 ... 0x400002ff:

These again want to have #define-s added.

> --- a/xen/arch/x86/traps.c
> +++ b/xen/arch/x86/traps.c
> @@ -776,29 +776,26 @@ static void do_trap(struct cpu_user_regs *regs)
>            trapnr, trapstr(trapnr), regs->error_code);
>  }
>  
> -/* Returns 0 if not handled, and non-0 for success. */
> -int rdmsr_hypervisor_regs(uint32_t idx, uint64_t *val)
> +int guest_rdmsr_xen(const struct vcpu *v, uint32_t idx, uint64_t *val)
>  {
> -    struct domain *d = current->domain;
> +    const struct domain *d = v->domain;
>      /* Optionally shift out of the way of Viridian architectural MSRs. */
>      uint32_t base = is_viridian_domain(d) ? 0x40000200 : 0x40000000;
>  
>      switch ( idx - base )
>      {
>      case 0: /* Write hypercall page MSR.  Read as zero. */
> -    {
>          *val = 0;
> -        return 1;
> -    }
> -    }
> +        return X86EMUL_OKAY;
>  
> -    return 0;
> +    default:
> +        return X86EMUL_EXCEPTION;
> +    }
>  }

Could I talk you into adjusting the code to have a "return" at the
end of the function, e.g. by dropping the default case? Also on
the write path then?

With at least the #define-s added,
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

Jan


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