Messages in this thread Patch in this message | | | Date | Wed, 20 Jul 2022 07:56:04 -0700 | From | Sathyanarayanan Kuppuswamy <> | Subject | Re: [PATCH v8 4/5] x86/mm: Add noalias variants of set_memory_*crypted() functions |
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Hi Kirill,
On 7/19/22 2:55 PM, Kirill A. Shutemov wrote: > On Tue, Jul 19, 2022 at 10:10:20AM -0700, Sathyanarayanan Kuppuswamy wrote: >>>> +static struct shmem_priv intel_shmem = { >>>> + .init = intel_shmem_init, >>>> + .alloc = intel_shmem_alloc, >>>> + .free = intel_shmem_free, >>>> +}; >>> >>> Hm. What is Intel-specific here. Looks like a generic thing, no? >>> >>> Maybe just drop all vendor stuff. CC_ATTR_MEM_ENCRYPT should be enough. >> >> I thought that not all CC vendors would want to use DMA APIs for shared >> buffer allocation. So adding a vendor layer would give them a way to implement >> their own model. > > set_memory_decrypted() is gated by CC_ATTR_MEM_ENCRYPT and it is the only > requirement for functionality AFAICS.
Makes sense. I think CC_ATTR_GUEST_MEM_ENCRYPT is the better check here. It force enables the SWIOTLB usage.
diff --git a/arch/x86/coco/Makefile b/arch/x86/coco/Makefile index c816acf78b6a..96fc4ec4497f 100644 --- a/arch/x86/coco/Makefile +++ b/arch/x86/coco/Makefile @@ -3,6 +3,6 @@ CFLAGS_REMOVE_core.o = -pg KASAN_SANITIZE_core.o := n CFLAGS_core.o += -fno-stack-protector -obj-y += core.o +obj-y += core.o mem.o obj-$(CONFIG_INTEL_TDX_GUEST) += tdx/ 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; +dma_addr_t handle; + +/* 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); +} + +static int cc_mem_probe(struct platform_device *pdev) +{ + if (dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(64))) + return -EIO; + + mem_pdev = pdev; + + return 0; +} + +static struct platform_driver cc_mem_driver = { + .probe = cc_mem_probe, + .driver = { + .name = CC_MEM_DRIVER, + }, +}; + +static int __init cc_mem_init(void) +{ + struct platform_device *pdev; + int ret; + + if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT)) + return -ENODEV; + + ret = platform_driver_register(&cc_mem_driver); + if (ret) + return ret; + + pdev = platform_device_register_simple(CC_MEM_DRIVER, -1, NULL, 0); + if (IS_ERR(pdev)) { + platform_driver_unregister(&cc_mem_driver); + return PTR_ERR(pdev); + } + + return 0; +} +device_initcall(cc_mem_init); diff --git a/arch/x86/include/asm/coco.h b/arch/x86/include/asm/coco.h index 3d98c3a60d34..9d616d9e3405 100644 --- a/arch/x86/include/asm/coco.h +++ b/arch/x86/include/asm/coco.h @@ -17,6 +17,8 @@ void cc_set_mask(u64 mask); #ifdef CONFIG_ARCH_HAS_CC_PLATFORM u64 cc_mkenc(u64 val); u64 cc_mkdec(u64 val); +void *cc_decrypted_alloc(size_t size, gfp_t gfp); +void cc_decrypted_free(void *addr, size_t size); #else static inline u64 cc_mkenc(u64 val) { @@ -27,6 +29,10 @@ static inline u64 cc_mkdec(u64 val) { return val; } + +void *cc_decrypted_alloc(size_t size, gfp_t gfp) { return NULL; } +void cc_decrypted_free(void *addr, size_t size) { } + #endif #endif /* _ASM_X86_COCO_H
>
-- Sathyanarayanan Kuppuswamy Linux Kernel Developer
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