From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> Intel TDX doesn't allow VMM to access guest private memory. Any memory that is required for communication with VMM must be shared explicitly by setting the bit in page table entry. After setting the shared bit, the conversion must be completed with MapGPA hypercall. You can find details about MapGPA hypercall in [1], sec 3.2. The call informs VMM about the conversion between private/shared mappings. The shared memory is similar to unencrypted memory in AMD SME/SEV terminology but the underlying process of sharing/un-sharing the memory is different for Intel TDX guest platform. SEV assumes that I/O devices can only do DMA to "decrypted" physical addresses without the C-bit set. In order for the CPU to interact with this memory, the CPU needs a decrypted mapping. To add this support, AMD SME code forces force_dma_unencrypted() to return true for platforms that support AMD SEV feature. It will be used for DMA memory allocation API to trigger set_memory_decrypted() for platforms that support AMD SEV feature. TDX is similar. So, to communicate with I/O devices, related pages need to be marked as shared. As mentioned above, shared memory in TDX architecture is similar to decrypted memory in AMD SME/SEV. So similar to AMD SEV, force_dma_unencrypted() has to forced to return true. This support is added in other patches in this series. So move force_dma_unencrypted() out of AMD specific code and call AMD specific (amd_force_dma_unencrypted()) initialization function from it. force_dma_unencrypted() will be modified by later patches to include Intel TDX guest platform specific initialization. Also, introduce new config option X86_MEM_ENCRYPT_COMMON that has to be selected by all x86 memory encryption features. This will be selected by both AMD SEV and Intel TDX guest config options. This is preparation for TDX changes in DMA code and it has no functional change. [1] - https://software.intel.com/content/dam/develop/external/us/en/documents/intel-tdx-guest-hypervisor-communication-interface.pdf Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Reviewed-by: Andi Kleen <ak@xxxxxxxxxxxxxxx> Reviewed-by: Tony Luck <tony.luck@xxxxxxxxx> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx> --- Change since v3: * None Changes since v1: * Removed sev_active(), sme_active() checks in force_dma_unencrypted(). arch/x86/Kconfig | 8 ++++++-- arch/x86/include/asm/mem_encrypt_common.h | 18 ++++++++++++++++++ arch/x86/mm/Makefile | 2 ++ arch/x86/mm/mem_encrypt.c | 3 ++- arch/x86/mm/mem_encrypt_common.c | 17 +++++++++++++++++ 5 files changed, 45 insertions(+), 3 deletions(-) create mode 100644 arch/x86/include/asm/mem_encrypt_common.h create mode 100644 arch/x86/mm/mem_encrypt_common.c diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index b500f2afacce..d66a8a2f3c97 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1524,16 +1524,20 @@ config X86_CPA_STATISTICS helps to determine the effectiveness of preserving large and huge page mappings when mapping protections are changed. +config X86_MEM_ENCRYPT_COMMON + select ARCH_HAS_FORCE_DMA_UNENCRYPTED + select DYNAMIC_PHYSICAL_MASK + def_bool n + config AMD_MEM_ENCRYPT bool "AMD Secure Memory Encryption (SME) support" depends on X86_64 && CPU_SUP_AMD select DMA_COHERENT_POOL - select DYNAMIC_PHYSICAL_MASK select ARCH_USE_MEMREMAP_PROT - select ARCH_HAS_FORCE_DMA_UNENCRYPTED select INSTRUCTION_DECODER select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS select ARCH_HAS_PROTECTED_GUEST + select X86_MEM_ENCRYPT_COMMON help Say yes to enable support for the encryption of system memory. This requires an AMD processor that supports Secure Memory diff --git a/arch/x86/include/asm/mem_encrypt_common.h b/arch/x86/include/asm/mem_encrypt_common.h new file mode 100644 index 000000000000..697bc40a4e3d --- /dev/null +++ b/arch/x86/include/asm/mem_encrypt_common.h @@ -0,0 +1,18 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (C) 2020 Intel Corporation */ +#ifndef _ASM_X86_MEM_ENCRYPT_COMMON_H +#define _ASM_X86_MEM_ENCRYPT_COMMON_H + +#include <linux/mem_encrypt.h> +#include <linux/device.h> + +#ifdef CONFIG_AMD_MEM_ENCRYPT +bool amd_force_dma_unencrypted(struct device *dev); +#else /* CONFIG_AMD_MEM_ENCRYPT */ +static inline bool amd_force_dma_unencrypted(struct device *dev) +{ + return false; +} +#endif /* CONFIG_AMD_MEM_ENCRYPT */ + +#endif diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile index 5864219221ca..b31cb52bf1bd 100644 --- a/arch/x86/mm/Makefile +++ b/arch/x86/mm/Makefile @@ -52,6 +52,8 @@ obj-$(CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS) += pkeys.o obj-$(CONFIG_RANDOMIZE_MEMORY) += kaslr.o obj-$(CONFIG_PAGE_TABLE_ISOLATION) += pti.o +obj-$(CONFIG_X86_MEM_ENCRYPT_COMMON) += mem_encrypt_common.o + obj-$(CONFIG_AMD_MEM_ENCRYPT) += mem_encrypt.o obj-$(CONFIG_AMD_MEM_ENCRYPT) += mem_encrypt_identity.o obj-$(CONFIG_AMD_MEM_ENCRYPT) += mem_encrypt_boot.o diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c index 7d3b2c6f5f88..1f7a72ce9d66 100644 --- a/arch/x86/mm/mem_encrypt.c +++ b/arch/x86/mm/mem_encrypt.c @@ -31,6 +31,7 @@ #include <asm/processor-flags.h> #include <asm/msr.h> #include <asm/cmdline.h> +#include <asm/mem_encrypt_common.h> #include "mm_internal.h" @@ -415,7 +416,7 @@ bool amd_prot_guest_has(unsigned int attr) EXPORT_SYMBOL(amd_prot_guest_has); /* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */ -bool force_dma_unencrypted(struct device *dev) +bool amd_force_dma_unencrypted(struct device *dev) { /* * For SEV, all DMA must be to unencrypted addresses. diff --git a/arch/x86/mm/mem_encrypt_common.c b/arch/x86/mm/mem_encrypt_common.c new file mode 100644 index 000000000000..f063c885b0a5 --- /dev/null +++ b/arch/x86/mm/mem_encrypt_common.c @@ -0,0 +1,17 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Memory Encryption Support Common Code + * + * Copyright (C) 2021 Intel Corporation + * + * Author: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx> + */ + +#include <asm/mem_encrypt_common.h> +#include <linux/dma-mapping.h> + +/* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */ +bool force_dma_unencrypted(struct device *dev) +{ + return amd_force_dma_unencrypted(dev); +} -- 2.25.1
