[Part1 PATCH v7 00/17] x86: Secure Encrypted Virtualization (AMD)

Brijesh Singh
2017-10-20T14:39:14Z

This part of Secure Encrypted Virtualization (SEV) series focuses on the
changes required in a guest OS for SEV support.

When SEV is active, the memory content of guest OS will be transparently
encrypted with a key unique to the guest VM.

SEV guests have concept of private and shared memory. Private memory is
encrypted with the guest-specific key, while shared memory may be encrypted with
hypervisor key. Certain type of memory (namely insruction pages and guest page
tables) are always treated as private. Due to security reasons all DMA
operations inside the guest must be performed on shared memory.

The SEV feature is enabled by the hypervisor, and guest can identify it through
CPUID function and the 0xc0010131 (F17H_SEV) MSR. When enabled, page table
entries will determine how memory is accessed. If a page table entry has the
memory encryption mask set, then that memory will be accessed using
guest-specific key. Certain memory (instruction pages, page tables) will always
be accessed using guest-specific key.

This patch series builds upon the Secure Memory Encryption (SME) feature. Unlike
SME, when SEV is enabled, all the data (e.g EFI, kernel, initrd, etc) will have
been placed into memory as encrypted by the guest BIOS.

The approach that this patch series takes is to encrypt everything possible
starting early in the boot. Since the DMA operations inside guest must be
performed on shared memory hence it uses SW-IOTLB to complete the DMA operations.

The following links provide additional details:

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

Secure Encrypted Virutualization Key Management:
http://support.amd.com/TechDocs/55766_SEV-KM API_Specification.pdf

KVM Forum Presentation:
http://www.linux-kvm.org/images/7/74/02x08A-Thomas_Lendacky-AMDs_Virtualizatoin_Memory_Encryption_Technology.pdf

SEV Guest BIOS support:
SEV support has been accepted into EDKII/OVMF BIOS
https://github.com/tianocore/edk2/commits/master

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim KrÃ„ÂmÃƒÂ¡Ã…â„¢" <rkrcmar@redhat.com>
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: x86@kernel.org

---
This series is based on tip/master commit : 7ffee292ddca (Merge branch 'x86/urgent')

Complete git tree is available: https://github.com/codomania/tip/tree/sev-v7-p1

Changes since v6:
* include jump_label.h to fix the build error seen with one of the randconfig

Changes since v5:
* enhance early_set_memory_decrypted() to do memory contents encrypt/decrypt in
addition to C bit changes.

Changes since v4:
* rename per-CPU define to DEFINE_PER_CPU_DECRYPTED
* add more comments in per-CPU section definition
* rename __sev_active() to sev_key_active() to use more obivious naming
* changes to address v4 feedbacks

Changes since v3:
* use static key to branch the unrolling of rep ins/outs when SEV is active
* simplify the memory encryption detection logic
* rename per-cpu define to DEFINE_PER_CPU_UNENCRYPTED
* simplfy the logic to map per-cpu as unencrypted
* changes to address v3 feedbacks

Changes since v2:
* add documentation
* update early_set_memory_* to use kernel_physical_mapping_init()
to split larger page into smaller (recommended by Boris)
* changes to address v2 feedback
* drop hypervisor specific patches, those patches will be included in part 2

Brijesh Singh (5):
Documentation/x86: Add AMD Secure Encrypted Virtualization (SEV)
description
x86: Add support for changing memory encryption attribute in early
boot
percpu: Introduce DEFINE_PER_CPU_DECRYPTED
X86/KVM: Decrypt shared per-cpu variables when SEV is active
X86/KVM: Clear encryption attribute when SEV is active

Tom Lendacky (12):
x86/mm: Add Secure Encrypted Virtualization (SEV) support
x86/mm: Don't attempt to encrypt initrd under SEV
x86/realmode: Don't decrypt trampoline area under SEV
x86/mm: Use encrypted access of boot related data with SEV
x86/mm: Include SEV for encryption memory attribute changes
x86/efi: Access EFI data as encrypted when SEV is active
resource: Consolidate resource walking code
resource: Provide resource struct in resource walk callback
x86/mm, resource: Use PAGE_KERNEL protection for ioremap of memory
pages
x86/mm: Add DMA support for SEV memory encryption
x86/boot: Add early boot support when running with SEV active
x86/io: Unroll string I/O when SEV is active

Documentation/x86/amd-memory-encryption.txt | 30 ++-
arch/powerpc/kernel/machine_kexec_file_64.c | 12 +-
arch/x86/boot/compressed/Makefile | 1 +
arch/x86/boot/compressed/head_64.S | 16 ++
arch/x86/boot/compressed/mem_encrypt.S | 120 +++++++++++
arch/x86/boot/compressed/misc.h | 2 +
arch/x86/boot/compressed/pagetable.c | 8 +-
arch/x86/entry/vdso/vma.c | 5 +-
arch/x86/include/asm/io.h | 43 +++-
arch/x86/include/asm/mem_encrypt.h | 14 ++
arch/x86/include/asm/msr-index.h | 3 +
arch/x86/include/uapi/asm/kvm_para.h | 1 -
arch/x86/kernel/crash.c | 18 +-
arch/x86/kernel/kvm.c | 40 +++-
arch/x86/kernel/kvmclock.c | 65 +++++-
arch/x86/kernel/pmem.c | 2 +-
arch/x86/kernel/setup.c | 6 +-
arch/x86/mm/ioremap.c | 123 +++++++++---
arch/x86/mm/mem_encrypt.c | 300 +++++++++++++++++++++++++++-
arch/x86/mm/pageattr.c | 4 +-
arch/x86/platform/efi/efi_64.c | 16 +-
arch/x86/realmode/init.c | 5 +-
include/asm-generic/vmlinux.lds.h | 19 ++
include/linux/ioport.h | 7 +-
include/linux/kexec.h | 2 +-
include/linux/mem_encrypt.h | 7 +-
include/linux/percpu-defs.h | 15 ++
kernel/kexec_file.c | 5 +-
kernel/resource.c | 76 ++++---
lib/swiotlb.c | 5 +-
30 files changed, 847 insertions(+), 123 deletions(-)
create mode 100644 arch/x86/boot/compressed/mem_encrypt.S

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