Re: [RFC PATCH v3 18/36] i386/tdvf: Introduce function to parse TDVF metadata

[Isaku Yamahata]

On Thu, Mar 17, 2022 at 09:58:55PM +0800,
Xiaoyao Li <xiaoyao.li@intel.com> wrote:

> diff --git a/hw/i386/tdvf.c b/hw/i386/tdvf.c
> new file mode 100644
> index 000000000000..02da1d2c12dd
> --- /dev/null
> +++ b/hw/i386/tdvf.c
> @@ -0,0 +1,196 @@
> +/*
> + * SPDX-License-Identifier: GPL-2.0-or-later
> +
> + * Copyright (c) 2020 Intel Corporation
> + * Author: Isaku Yamahata <isaku.yamahata at gmail.com>
> + *                        <isaku.yamahata at intel.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> +
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> +
> + * You should have received a copy of the GNU General Public License along
> + * with this program; if not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "hw/i386/pc.h"
> +#include "hw/i386/tdvf.h"
> +#include "sysemu/kvm.h"
> +
> +#define TDX_METADATA_GUID "e47a6535-984a-4798-865e-4685a7bf8ec2"
> +#define TDX_METADATA_VERSION    1
> +#define TDVF_SIGNATURE_LE32     0x46564454 /* TDVF as little endian */

_LE32 doesn't make sense.  qemu doesn't provide macro version for byteswap.
Let's convert at the usage point.


> +
> +typedef struct {
> +    uint32_t DataOffset;
> +    uint32_t RawDataSize;
> +    uint64_t MemoryAddress;
> +    uint64_t MemoryDataSize;
> +    uint32_t Type;
> +    uint32_t Attributes;
> +} TdvfSectionEntry;
> +
> +typedef struct {
> +    uint32_t Signature;
> +    uint32_t Length;
> +    uint32_t Version;
> +    uint32_t NumberOfSectionEntries;
> +    TdvfSectionEntry SectionEntries[];
> +} TdvfMetadata;
> +
> +struct tdx_metadata_offset {
> +    uint32_t offset;
> +};
> +
> +static TdvfMetadata *tdvf_get_metadata(void *flash_ptr, int size)
> +{
> +    TdvfMetadata *metadata;
> +    uint32_t offset = 0;
> +    uint8_t *data;
> +
> +    if ((uint32_t) size != size) {
> +        return NULL;
> +    }
> +
> +    if (pc_system_ovmf_table_find(TDX_METADATA_GUID, &data, NULL)) {
> +        offset = size - le32_to_cpu(((struct tdx_metadata_offset 
> *)data)->offset);
> +
> +        if (offset + sizeof(*metadata) > size) {
> +            return NULL;
> +        }
> +    } else {
> +        error_report("Cannot find TDX_METADATA_GUID\n");
> +        return NULL;
> +    }
> +
> +    metadata = flash_ptr + offset;
> +
> +    /* Finally, verify the signature to determine if this is a TDVF image. */
> +   if (metadata->Signature != TDVF_SIGNATURE_LE32) {


metadata->Signature = le32_to_cpu(metadata->Signature);
metadata->Signature != TDVF_SIGNATURE for consistency.

-- 
Isaku Yamahata <isaku.yamahata@gmail.com>