Re: [Xen-devel] [PATCH v3 25/25] x86/shadow: fold sh_x86_emulate_{write, cmpxchg}() into their only callers

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 07/12/17 14:19, Jan Beulich wrote:
> @@ -298,14 +332,43 @@ hvm_emulate_cmpxchg(enum x86_segment seg
>      if ( rc )
>          return rc;
>  
> +    /* Unaligned writes are only acceptable on HVM */
> +    if ( (addr & (bytes - 1)) && !is_hvm_vcpu(v)  )
> +        return X86EMUL_UNHANDLEABLE;
> +
> +    ptr = sh_emulate_map_dest(v, addr, bytes, sh_ctxt);
> +    if ( IS_ERR(ptr) )
> +        return ~PTR_ERR(ptr);
> +
>      old = new = 0;
>      memcpy(&old, p_old, bytes);
>      memcpy(&new, p_new, bytes);
>  
> -    rc = v->arch.paging.mode->shadow.x86_emulate_cmpxchg(
> -             v, addr, &old, new, bytes, sh_ctxt);
> +    paging_lock(v->domain);
> +    switch ( bytes )
> +    {
> +    case 1: prev = cmpxchg((uint8_t  *)ptr, old, new); break;
> +    case 2: prev = cmpxchg((uint16_t *)ptr, old, new); break;
> +    case 4: prev = cmpxchg((uint32_t *)ptr, old, new); break;
> +    case 8: prev = cmpxchg((uint64_t *)ptr, old, new); break;
> +    default:
> +        SHADOW_PRINTK("cmpxchg size %u is not supported\n", bytes);

Given the earlier patches in the series, is it worth introducing case 16
here?

Irrespective, this doesn't interfere with the purpose of the patch, so
Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

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