Re: [PATCH v3 23/75] x86/boot/compressed/64: Setup GHCB Based VC Exception handler

[Borislav Petkov]

On Tue, Apr 28, 2020 at 05:16:33PM +0200, Joerg Roedel wrote:
> @@ -63,3 +175,45 @@ void __init do_vc_no_ghcb(struct pt_regs *regs, unsigned long exit_code)
>  	while (true)
>  		asm volatile("hlt\n");
>  }
> +
> +static enum es_result vc_insn_string_read(struct es_em_ctxt *ctxt,
> +					  void *src, char *buf,
> +					  unsigned int data_size,
> +					  unsigned int count,
> +					  bool backwards)
> +{
> +	int i, b = backwards ? -1 : 1;
> +	enum es_result ret = ES_OK;
> +
> +	for (i = 0; i < count; i++) {
> +		void *s = src + (i * data_size * b);
> +		char *d = buf + (i * data_size);

>From a previous review:

Where are we checking whether that count is not exceeding @buf or
similar discrepancies?

Ditto below.

> +
> +		ret = vc_read_mem(ctxt, s, d, data_size);
> +		if (ret != ES_OK)
> +			break;
> +	}
> +
> +	return ret;
> +}
> +
> +static enum es_result vc_insn_string_write(struct es_em_ctxt *ctxt,
> +					   void *dst, char *buf,
> +					   unsigned int data_size,
> +					   unsigned int count,
> +					   bool backwards)
> +{
> +	int i, s = backwards ? -1 : 1;
> +	enum es_result ret = ES_OK;
> +
> +	for (i = 0; i < count; i++) {
> +		void *d = dst + (i * data_size * s);
> +		char *b = buf + (i * data_size);
> +
> +		ret = vc_write_mem(ctxt, d, b, data_size);
> +		if (ret != ES_OK)
> +			break;
> +	}
> +
> +	return ret;
> +}
> -- 
> 2.17.1
> 

-- 
Regards/Gruss,
    Boris.

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