linux-kernel - Re: [PATCH] x86/sev: Move sev_setup_arch() to mem

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Message-ID: <873530zh74.fsf@ubik.fi.intel.com>
Date:   Fri, 09 Jun 2023 20:19:43 +0300
From:   Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To:     Alison Schofield <alison.schofield@...el.com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        alexander.shishkin@...ux.intel.com
Subject: Re: [PATCH] x86/sev: Move sev_setup_arch() to mem_encrypt.c

Alison Schofield <alison.schofield@...el.com> writes:

> On Tue, May 30, 2023 at 03:17:28PM +0300, Alexander Shishkin wrote:
>> Since commit 4d96f9109109b ("x86/sev: Replace occurrences of
>> sev_active() with cc_platform_has()"), the SWIOTLB bounce buffer size
>> adjustment and restricted virtio memory setting also inadvertently apply
>> to TDX, which just happens to be what we want.
>
> Hi Alexander,

Hi Alison,

> Can you offer more context on how this inadvertently applies?

Yes, the code uses cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) condition
for setting the bounce buffer size and enabling restricted virtio
memory, which is also true for TDX. I've added a bit about this to v2
[0].

> One bit below...
>> --- a/arch/x86/mm/mem_encrypt.c
>> +++ b/arch/x86/mm/mem_encrypt.c
>> @@ -12,6 +12,7 @@
>>  #include <linux/swiotlb.h>
>>  #include <linux/cc_platform.h>
>>  #include <linux/mem_encrypt.h>
>> +#include <linux/virtio_anchor.h>
>
> It looks like this #include can be removed from mem_encrypt_amd.c 

Good catch! This is also addressed in v2.

[0] https://lore.kernel.org/lkml/20230609171214.31846-1-alexander.shishkin@linux.intel.com/

Thanks,
--
Alex