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

Borislav Petkov
2020-05-11T20:07:18Z

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.