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Message-ID: <CAOcCaLYWoOu0c-Fkee-=wegNqkzUp9pLFLmaFrXuhiXRnUZ3Xw@mail.gmail.com>
Date: Wed, 7 Jun 2017 22:40:03 -0400
From: Nick Sarnie <commendsarnex@...il.com>
To: Tom Lendacky <thomas.lendacky@....com>
Cc: linux-arch@...r.kernel.org, linux-efi@...r.kernel.org,
kvm@...r.kernel.org, linux-doc@...r.kernel.org, x86@...nel.org,
kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
kasan-dev@...glegroups.com, linux-mm@...ck.org,
iommu@...ts.linux-foundation.org,
Thomas Gleixner <tglx@...utronix.de>,
Rik van Riel <riel@...hat.com>,
Brijesh Singh <brijesh.singh@....com>,
Toshimitsu Kani <toshi.kani@....com>,
Arnd Bergmann <arnd@...db.de>,
Jonathan Corbet <corbet@....net>,
Matt Fleming <matt@...eblueprint.co.uk>,
Radim Krčmář <rkrcmar@...hat.com>,
Andrey Ryabinin <aryabinin@...tuozzo.com>,
Ingo Molnar <mingo@...hat.com>,
"Michael S. Tsirkin" <mst@...hat.com>,
Andy Lutomirski <luto@...nel.org>,
"H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>,
Paolo Bonzini <pbonzini@...hat.com>,
Alexander Potapenko <glider@...gle.com>,
Dave Young <dyoung@...hat.com>,
Larry Woodman <lwoodman@...hat.com>,
Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: [PATCH v6 00/34] x86: Secure Memory Encryption (AMD)
On Wed, Jun 7, 2017 at 3:13 PM, Tom Lendacky <thomas.lendacky@....com> wrote:
> This patch series provides support for AMD's new Secure Memory Encryption (SME)
> feature.
>
> SME can be used to mark individual pages of memory as encrypted through the
> page tables. A page of memory that is marked encrypted will be automatically
> decrypted when read from DRAM and will be automatically encrypted when
> written to DRAM. Details on SME can found in the links below.
>
> The SME feature is identified through a CPUID function and enabled through
> the SYSCFG MSR. Once enabled, page table entries will determine how the
> memory is accessed. If a page table entry has the memory encryption mask set,
> then that memory will be accessed as encrypted memory. The memory encryption
> mask (as well as other related information) is determined from settings
> returned through the same CPUID function that identifies the presence of the
> feature.
>
> The approach that this patch series takes is to encrypt everything possible
> starting early in the boot where the kernel is encrypted. Using the page
> table macros the encryption mask can be incorporated into all page table
> entries and page allocations. By updating the protection map, userspace
> allocations are also marked encrypted. Certain data must be accounted for
> as having been placed in memory before SME was enabled (EFI, initrd, etc.)
> and accessed accordingly.
>
> This patch series is a pre-cursor to another AMD processor feature called
> Secure Encrypted Virtualization (SEV). The support for SEV will build upon
> the SME support and will be submitted later. Details on SEV can be found
> in the links below.
>
> The following links provide additional detail:
>
> AMD Memory Encryption whitepaper:
> http://amd-dev.wpengine.netdna-cdn.com/wordpress/media/2013/12/AMD_Memory_Encryption_Whitepaper_v7-Public.pdf
>
> AMD64 Architecture Programmer's Manual:
> http://support.amd.com/TechDocs/24593.pdf
> SME is section 7.10
> SEV is section 15.34
>
> ---
>
> This patch series is based off of the master branch of tip.
> Commit 53614fbd7961 ("Merge branch 'WIP.x86/fpu'")
>
> Source code is also available at https://github.com/codomania/tip/tree/sme-v6
>
>
> Still to do:
> - Kdump support, including using memremap() instead of ioremap_cache()
>
> Changes since v5:
> - Added support for 5-level paging
> - Added IOMMU support
> - Created a generic asm/mem_encrypt.h in order to remove a bunch of
> #ifndef/#define entries
> - Removed changes to the __va() macro and defined a function to return
> the true physical address in cr3
> - Removed sysfs support as it was determined not to be needed
> - General code cleanup based on feedback
> - General cleanup of patch subjects and descriptions
>
> Changes since v4:
> - Re-worked mapping of setup data to not use a fixed list. Rather, check
> dynamically whether the requested early_memremap()/memremap() call
> needs to be mapped decrypted.
> - Moved SME cpu feature into scattered features
> - Moved some declarations into header files
> - Cleared the encryption mask from the __PHYSICAL_MASK so that users
> of macros such as pmd_pfn_mask() don't have to worry/know about the
> encryption mask
> - Updated some return types and values related to EFI and e820 functions
> so that an error could be returned
> - During cpu shutdown, removed cache disabling and added a check for kexec
> in progress to use wbinvd followed immediately by halt in order to avoid
> any memory corruption
> - Update how persistent memory is identified
> - Added a function to find command line arguments and their values
> - Added sysfs support
> - General code cleanup based on feedback
> - General cleanup of patch subjects and descriptions
>
>
> Changes since v3:
> - Broke out some of the patches into smaller individual patches
> - Updated Documentation
> - Added a message to indicate why the IOMMU was disabled
> - Updated CPU feature support for SME by taking into account whether
> BIOS has enabled SME
> - Eliminated redundant functions
> - Added some warning messages for DMA usage of bounce buffers when SME
> is active
> - Added support for persistent memory
> - Added support to determine when setup data is being mapped and be sure
> to map it un-encrypted
> - Added CONFIG support to set the default action of whether to activate
> SME if it is supported/enabled
> - Added support for (re)booting with kexec
>
> Changes since v2:
> - Updated Documentation
> - Make the encryption mask available outside of arch/x86 through a
> standard include file
> - Conversion of assembler routines to C where possible (not everything
> could be converted, e.g. the routine that does the actual encryption
> needs to be copied into a safe location and it is difficult to
> determine the actual length of the function in order to copy it)
> - Fix SME feature use of scattered CPUID feature
> - Creation of SME specific functions for things like encrypting
> the setup data, ramdisk, etc.
> - New take on early_memremap / memremap encryption support
> - Additional support for accessing video buffers (fbdev/gpu) as
> un-encrypted
> - Disable IOMMU for now - need to investigate further in relation to
> how it needs to be programmed relative to accessing physical memory
>
> Changes since v1:
> - Added Documentation.
> - Removed AMD vendor check for setting the PAT write protect mode
> - Updated naming of trampoline flag for SME as well as moving of the
> SME check to before paging is enabled.
> - Change to early_memremap to identify the data being mapped as either
> boot data or kernel data. The idea being that boot data will have
> been placed in memory as un-encrypted data and would need to be accessed
> as such.
> - Updated debugfs support for the bootparams to access the data properly.
> - Do not set the SYSCFG[MEME] bit, only check it. The setting of the
> MemEncryptionModeEn bit results in a reduction of physical address size
> of the processor. It is possible that BIOS could have configured resources
> resources into a range that will now not be addressable. To prevent this,
> rely on BIOS to set the SYSCFG[MEME] bit and only then enable memory
> encryption support in the kernel.
>
> Tom Lendacky (34):
> x86: Document AMD Secure Memory Encryption (SME)
> x86/mm/pat: Set write-protect cache mode for full PAT support
> x86, mpparse, x86/acpi, x86/PCI, x86/dmi, SFI: Use memremap for RAM mappings
> x86/CPU/AMD: Add the Secure Memory Encryption CPU feature
> x86/CPU/AMD: Handle SME reduction in physical address size
> x86/mm: Add Secure Memory Encryption (SME) support
> x86/mm: Don't use phys_to_virt in ioremap() if SME is active
> x86/mm: Add support to enable SME in early boot processing
> x86/mm: Simplify p[gum]d_page() macros
> x86, x86/mm, x86/xen, olpc: Use __va() against just the physical address in cr3
> x86/mm: Provide general kernel support for memory encryption
> x86/mm: Extend early_memremap() support with additional attrs
> x86/mm: Add support for early encrypt/decrypt of memory
> x86/mm: Insure that boot memory areas are mapped properly
> x86/boot/e820: Add support to determine the E820 type of an address
> efi: Add an EFI table address match function
> efi: Update efi_mem_type() to return an error rather than 0
> x86/efi: Update EFI pagetable creation to work with SME
> x86/mm: Add support to access boot related data in the clear
> x86, mpparse: Use memremap to map the mpf and mpc data
> x86/mm: Add support to access persistent memory in the clear
> x86/mm: Add support for changing the memory encryption attribute
> x86, realmode: Decrypt trampoline area if memory encryption is active
> x86, swiotlb: Add memory encryption support
> swiotlb: Add warnings for use of bounce buffers with SME
> iommu/amd: Allow the AMD IOMMU to work with memory encryption
> x86, realmode: Check for memory encryption on the APs
> x86, drm, fbdev: Do not specify encrypted memory for video mappings
> kvm: x86: svm: Support Secure Memory Encryption within KVM
> x86/mm, kexec: Allow kexec to be used with SME
> x86/mm: Use proper encryption attributes with /dev/mem
> x86/mm: Add support to encrypt the kernel in-place
> x86/boot: Add early cmdline parsing for options with arguments
> x86/mm: Add support to make use of Secure Memory Encryption
>
>
> Documentation/admin-guide/kernel-parameters.txt | 11
> Documentation/x86/amd-memory-encryption.txt | 68 ++
> arch/ia64/kernel/efi.c | 4
> arch/x86/Kconfig | 26 +
> arch/x86/boot/compressed/pagetable.c | 7
> arch/x86/include/asm/cmdline.h | 2
> arch/x86/include/asm/cpufeatures.h | 1
> arch/x86/include/asm/dma-mapping.h | 5
> arch/x86/include/asm/dmi.h | 8
> arch/x86/include/asm/e820/api.h | 2
> arch/x86/include/asm/fixmap.h | 20 +
> arch/x86/include/asm/init.h | 1
> arch/x86/include/asm/io.h | 7
> arch/x86/include/asm/kexec.h | 8
> arch/x86/include/asm/kvm_host.h | 2
> arch/x86/include/asm/mem_encrypt.h | 112 ++++
> arch/x86/include/asm/msr-index.h | 2
> arch/x86/include/asm/page_types.h | 2
> arch/x86/include/asm/pgtable.h | 28 +
> arch/x86/include/asm/pgtable_types.h | 54 +-
> arch/x86/include/asm/processor.h | 3
> arch/x86/include/asm/realmode.h | 12
> arch/x86/include/asm/set_memory.h | 3
> arch/x86/include/asm/special_insns.h | 9
> arch/x86/include/asm/vga.h | 14
> arch/x86/kernel/acpi/boot.c | 6
> arch/x86/kernel/cpu/amd.c | 17 +
> arch/x86/kernel/cpu/scattered.c | 1
> arch/x86/kernel/e820.c | 26 +
> arch/x86/kernel/espfix_64.c | 2
> arch/x86/kernel/head64.c | 42 +
> arch/x86/kernel/head_64.S | 80 ++-
> arch/x86/kernel/kdebugfs.c | 34 -
> arch/x86/kernel/ksysfs.c | 28 -
> arch/x86/kernel/machine_kexec_64.c | 35 +
> arch/x86/kernel/mpparse.c | 108 +++-
> arch/x86/kernel/pci-dma.c | 11
> arch/x86/kernel/pci-nommu.c | 2
> arch/x86/kernel/pci-swiotlb.c | 15 -
> arch/x86/kernel/process.c | 17 +
> arch/x86/kernel/setup.c | 9
> arch/x86/kvm/mmu.c | 12
> arch/x86/kvm/mmu.h | 2
> arch/x86/kvm/svm.c | 35 +
> arch/x86/kvm/vmx.c | 3
> arch/x86/kvm/x86.c | 3
> arch/x86/lib/cmdline.c | 105 ++++
> arch/x86/mm/Makefile | 3
> arch/x86/mm/fault.c | 10
> arch/x86/mm/ident_map.c | 12
> arch/x86/mm/ioremap.c | 277 +++++++++-
> arch/x86/mm/kasan_init_64.c | 4
> arch/x86/mm/mem_encrypt.c | 667 +++++++++++++++++++++++
> arch/x86/mm/mem_encrypt_boot.S | 150 +++++
> arch/x86/mm/pageattr.c | 67 ++
> arch/x86/mm/pat.c | 9
> arch/x86/pci/common.c | 4
> arch/x86/platform/efi/efi.c | 6
> arch/x86/platform/efi/efi_64.c | 15 -
> arch/x86/platform/olpc/olpc-xo1-pm.c | 2
> arch/x86/power/hibernate_64.c | 2
> arch/x86/realmode/init.c | 15 +
> arch/x86/realmode/rm/trampoline_64.S | 24 +
> arch/x86/xen/mmu_pv.c | 6
> drivers/firmware/dmi-sysfs.c | 5
> drivers/firmware/efi/efi.c | 33 +
> drivers/firmware/pcdp.c | 4
> drivers/gpu/drm/drm_gem.c | 2
> drivers/gpu/drm/drm_vm.c | 4
> drivers/gpu/drm/ttm/ttm_bo_vm.c | 7
> drivers/gpu/drm/udl/udl_fb.c | 4
> drivers/iommu/amd_iommu.c | 36 +
> drivers/iommu/amd_iommu_init.c | 18 -
> drivers/iommu/amd_iommu_proto.h | 10
> drivers/iommu/amd_iommu_types.h | 2
> drivers/sfi/sfi_core.c | 22 -
> drivers/video/fbdev/core/fbmem.c | 12
> include/asm-generic/early_ioremap.h | 2
> include/asm-generic/mem_encrypt.h | 45 ++
> include/asm-generic/pgtable.h | 8
> include/linux/dma-mapping.h | 9
> include/linux/efi.h | 9
> include/linux/io.h | 2
> include/linux/kexec.h | 14
> include/linux/mem_encrypt.h | 18 +
> include/linux/swiotlb.h | 1
> init/main.c | 13
> kernel/kexec_core.c | 6
> kernel/memremap.c | 20 +
> lib/swiotlb.c | 59 ++
> mm/early_ioremap.c | 30 +
> 91 files changed, 2411 insertions(+), 261 deletions(-)
> create mode 100644 Documentation/x86/amd-memory-encryption.txt
> create mode 100644 arch/x86/include/asm/mem_encrypt.h
> create mode 100644 arch/x86/mm/mem_encrypt.c
> create mode 100644 arch/x86/mm/mem_encrypt_boot.S
> create mode 100644 include/asm-generic/mem_encrypt.h
> create mode 100644 include/linux/mem_encrypt.h
>
> --
> Tom Lendacky
> _______________________________________________
> iommu mailing list
> iommu@...ts.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu
Hi Tom,
Thanks for your work on this. This may be a stupid question, but is
using bounce buffers for the GPU(s) expected to reduce performance in
any/a noticeable way? I'm hitting another issue which I've already
sent mail about so I can't test it for myself at the moment,
Thanks,
Sarnex
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