linux-kernel - Re: [PATCH v19 033/130] KVM: TDX: Add helper function to read TDX metadata in array

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Date: Thu, 14 Mar 2024 22:35:47 +0800
From: Binbin Wu <binbin.wu@...ux.intel.com>
To: isaku.yamahata@...el.com
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
 isaku.yamahata@...il.com, Paolo Bonzini <pbonzini@...hat.com>,
 erdemaktas@...gle.com, Sean Christopherson <seanjc@...gle.com>,
 Sagi Shahar <sagis@...gle.com>, Kai Huang <kai.huang@...el.com>,
 chen.bo@...el.com, hang.yuan@...el.com, tina.zhang@...el.com
Subject: Re: [PATCH v19 033/130] KVM: TDX: Add helper function to read TDX
 metadata in array



On 3/14/2024 5:17 PM, Binbin Wu wrote:
>
>
> On 2/26/2024 4:25 PM, isaku.yamahata@...el.com wrote:
>> From: Isaku Yamahata <isaku.yamahata@...el.com>
>>
>> To read meta data in series, use table.
>> Instead of metadata_read(fid0, &data0); metadata_read(...); ...
>> table = { {fid0, &data0}, ...}; metadata-read(tables).
>> TODO: Once the TDX host code introduces its framework to read TDX 
>> metadata,
>> drop this patch and convert the code that uses this.
>
> Do you mean the patch 1-5 included in this patch set.
> I think the patch 1-5 of this patch set is doing this thing, right?
>
> Since they are already there, I think you can use them directly in this
> patch set instead of introducing these temp code?
I may have some mis-understanding, but I think the TODO has been done, 
right?

>
>>
>> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
>> ---
>> v18:
>> - newly added
>> ---
>>   arch/x86/kvm/vmx/tdx.c | 45 ++++++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 45 insertions(+)
>>
>> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
>> index cde971122c1e..dce21f675155 100644
>> --- a/arch/x86/kvm/vmx/tdx.c
>> +++ b/arch/x86/kvm/vmx/tdx.c
>> @@ -6,6 +6,7 @@
>>   #include "capabilities.h"
>>   #include "x86_ops.h"
>>   #include "x86.h"
>> +#include "tdx_arch.h"
>>   #include "tdx.h"
>>     #undef pr_fmt
>> @@ -39,6 +40,50 @@ static void __used tdx_guest_keyid_free(int keyid)
>>       ida_free(&tdx_guest_keyid_pool, keyid);
>>   }
>>   +#define TDX_MD_MAP(_fid, _ptr)            \
>> +    { .fid = MD_FIELD_ID_##_fid,        \
>> +      .ptr = (_ptr), }
>> +
>> +struct tdx_md_map {
>> +    u64 fid;
>> +    void *ptr;
>> +};
>> +
>> +static size_t tdx_md_element_size(u64 fid)
>> +{
>> +    switch (TDX_MD_ELEMENT_SIZE_CODE(fid)) {
>> +    case TDX_MD_ELEMENT_SIZE_8BITS:
>> +        return 1;
>> +    case TDX_MD_ELEMENT_SIZE_16BITS:
>> +        return 2;
>> +    case TDX_MD_ELEMENT_SIZE_32BITS:
>> +        return 4;
>> +    case TDX_MD_ELEMENT_SIZE_64BITS:
>> +        return 8;
>> +    default:
>> +        WARN_ON_ONCE(1);
>> +        return 0;
>> +    }
>> +}
>> +
>> +static int __used tdx_md_read(struct tdx_md_map *maps, int nr_maps)
>> +{
>> +    struct tdx_md_map *m;
>> +    int ret, i;
>> +    u64 tmp;
>> +
>> +    for (i = 0; i < nr_maps; i++) {
>> +        m = &maps[i];
>> +        ret = tdx_sys_metadata_field_read(m->fid, &tmp);
>> +        if (ret)
>> +            return ret;
>> +
>> +        memcpy(m->ptr, &tmp, tdx_md_element_size(m->fid));
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>>   static int __init tdx_module_setup(void)
>>   {
>>       int ret;
>