linux-kernel - Re: [PATCH v5 3/3] x86/tdx: Add Quote generation support

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Date:   Thu, 5 May 2022 15:38:43 -0700
From:   Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
To:     Kai Huang <kai.huang@...el.com>,
        Dave Hansen <dave.hansen@...el.com>,
        "Kirill A. Shutemov" <kirill@...temov.name>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H . Peter Anvin" <hpa@...or.com>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Tony Luck <tony.luck@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Wander Lairson Costa <wander@...hat.com>,
        Isaku Yamahata <isaku.yamahata@...il.com>,
        marcelo.cerri@...onical.com, tim.gardner@...onical.com,
        khalid.elmously@...onical.com, philip.cox@...onical.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 3/3] x86/tdx: Add Quote generation support



On 5/5/22 3:15 PM, Kai Huang wrote:
> On Thu, 2022-05-05 at 13:53 -0700, Sathyanarayanan Kuppuswamy wrote:
>> Hi Kai,
>>
>> On 5/4/22 4:28 PM, Kai Huang wrote:
>>> On Wed, 2022-05-04 at 15:49 -0700, Sathyanarayanan Kuppuswamy wrote:
>>>> --- a/arch/x86/coco/tdx/tdx.c
>>>> +++ b/arch/x86/coco/tdx/tdx.c
>>>> @@ -15,6 +15,7 @@
>>>>     #include <asm/idtentry.h>
>>>>     #include <asm/irq_regs.h>
>>>>     #include <asm/desc.h>
>>>> +#include <asm/io.h>
>>>>
>>>>     /* TDX module Call Leaf IDs */
>>>>     #define TDX_GET_INFO                   1
>>>> @@ -680,8 +681,15 @@ static bool try_accept_one(phys_addr_t *start,
>>>> unsigned long len,
>>>>      */
>>>>     static bool tdx_enc_status_changed(unsigned long vaddr, int numpages,
>>>> bool enc)
>>>>     {
>>>> -       phys_addr_t start = __pa(vaddr);
>>>> -       phys_addr_t end   = __pa(vaddr + numpages * PAGE_SIZE);
>>>> +       phys_addr_t start;
>>>> +       phys_addr_t end;
>>>> +
>>>> +       if (is_vmalloc_addr((void *)vaddr))
>>>> +               start =  page_to_phys(vmalloc_to_page((void*)vaddr));
>>>> +       else
>>>> +               start = __pa(vaddr);
>>>> +
>>>> +       end = start + numpages * PAGE_SIZE;
>>>>
>>>>            if (!enc) {
>>>>                    /* Set the shared (decrypted) bits: */
>>>
>>> Looks set_memory_decrypted() only works for direct-mapping, so you should not
>>> use this.  Instead, you can pass shared bit in 'prot' argument (using
>>> pgprot_decrypted()) when you call vmap(), and explicitly call MapGPA().
>>
>> Is it because of the above change, or you see other direct-mapping
>> dependencies in set_memory_*() functions?
>>
>>
>>
> set_memory_xx()  is supposedly only for direct-mapping.  Please use my
> suggestion above.

I did not find any other direct-mapping dependency in set_memory_*()
functions other than what I have fixed. If I missed anything, please
let me know.

Also, even if set_memory_*() functions does not support vmalloc'ed
memory,  IMO, it is better to add this support to it.

I want to avoid custom solution if it is possible to use generic
function.

> 

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer