Re: [PATCH v8 4/5] x86/mm: Add noalias variants of set_memory_*crypted() functions

[Sathyanarayanan Kuppuswamy]

On 7/20/22 9:17 AM, Kirill A. Shutemov wrote:
> On Wed, Jul 20, 2022 at 07:56:04AM -0700, Sathyanarayanan Kuppuswamy wrote:
>> diff --git a/arch/x86/coco/mem.c b/arch/x86/coco/mem.c
>> new file mode 100644
>> index 000000000000..ef76a8accc1e
>> --- /dev/null
>> +++ b/arch/x86/coco/mem.c
>> @@ -0,0 +1,82 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Confidential Computing Decrypted Memory Allocator
>> + *
>> + * Copyright (C) 2022 Intel Corporation, Inc.
>> + *
>> + */
>> +
>> +#undef pr_fmt
>> +#define pr_fmt(fmt)     "cc/mem: " fmt
>> +
>> +#include <linux/export.h>
>> +#include <linux/mm.h>
>> +#include <linux/cc_platform.h>
>> +#include <linux/set_memory.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/dma-mapping.h>
>> +
>> +#include <asm/coco.h>
>> +#include <asm/processor.h>
>> +
>> +#define CC_MEM_DRIVER          "ccmem"
>> +
>> +struct platform_device *mem_pdev;
> 
> 'static'?

Agree.

> 
>> +dma_addr_t handle;
> 
> Hm. How does it work with >1 allocation a time?

It is a bug. I think we should make it as parameter to alloc/free APIs.

> 
>> +
>> +/* Allocate decrypted memory of given size */
>> +void *cc_decrypted_alloc(size_t size, gfp_t gfp)
>> +{
>> +       if (!mem_pdev)
>> +               return NULL;
>> +
>> +       return dma_alloc_coherent(&mem_pdev->dev, size, &handle, gfp);
>> +}
>> +
>> +/* Free given decrypted memory */
>> +void cc_decrypted_free(void *addr, size_t size)
>> +{
>> +       if (!mem_pdev)
>> +               return;
>> +
>> +       dma_free_coherent(&mem_pdev->dev, size, addr, handle);
>> +}
>> +
> 

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer