Re: [Part2 PATCH v9 00/38] x86: Secure Encrypted Virtualization (AMD)

From: Paolo Bonzini
Date: Thu Dec 21 2017 - 08:06:31 EST

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On 05/12/2017 02:04, Brijesh Singh wrote:
> This part of Secure Encrypted Virtualization (SEV) patch series focuses on KVM
> changes required to create and manage SEV guests.
>
> SEV is an extension to the AMD-V architecture which supports running encrypted
> virtual machine (VMs) under the control of a hypervisor. Encrypted VMs have their
> pages (code and data) secured such that only the guest itself has access to
> unencrypted version. Each encrypted VM is associated with a unique encryption key;
> if its data is accessed to a different entity using a different key the encrypted
> guest's data will be incorrectly decrypted, leading to unintelligible data.
> This security model ensures that hypervisor will no longer able to inspect or
> alter any guest code or data.
>
> The key management of this feature is handled by a separate processor known as
> the AMD Secure Processor (AMD-SP) which is present on AMD SOCs. The SEV Key
> Management Specification (see below) provides a set of commands which can be
> used by hypervisor to load virtual machine keys through the AMD-SP driver.
>
> The patch series adds a new ioctl in KVM driver (KVM_MEMORY_ENCRYPT_OP). The
> ioctl will be used by qemu to issue SEV guest-specific commands defined in Key
> Management Specification.

Hi Brijesh,

I have a couple comments:

1) how is MSR_AMD64_SEV's value passed to the guest, and where is it in
the manual?

2) ECX should be 0 in the guest's 0x8000_001f leaf, because we don't
support nested SEV guests. Likewise, EAX bit 2 should be 0 since you
don't emulate the page flush MSR.

Both can be fixed on top (and I can do the second myself of course), so
there should be no need for a v10. But MSR_AMD64_SEV is leaving me
quite puzzled.

Thanks,

Paolo

> The following links provide additional details:
>
> AMD Memory Encryption white paper:
> 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
>
> SEV 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 add to EDKII/OVMF BIOS
> https://github.com/tianocore/edk2
>
> --
>
> The series applies on kvm/next commit : 4fbd8d194f06 (Linux 4.15-rc1)
>
> Complete tree is available at:
> repo: https://github.com/codomania/kvm.git
> branch: sev-v9-p2
>
> TODO:
> * Add SEV guest migration command support
>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Cc: "Radim KrÃÂmÃÂÃâ" <rkrcmar@xxxxxxxxxx>
> Cc: Joerg Roedel <joro@xxxxxxxxxx>
> Cc: Borislav Petkov <bp@xxxxxxx>
> Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
> Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> Cc: David S. Miller <davem@xxxxxxxxxxxxx>
> Cc: Gary Hook <gary.hook@xxxxxxx>
> Cc: x86@xxxxxxxxxx
> Cc: kvm@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: linux-crypto@xxxxxxxxxxxxxxx
>
> Changes since v8:
> * Rebase the series to kvm/next branch
> * Update SEV asid allocation to limit the ASID between SEV_MIN_ASID to SEV_MAX_ASID
> (EPYC BIOS provide option to change the SEV_MIN_ASID -- which can be used to
> limit the number of SEV-enable guest)
>
> Changes since v7:
> * Rebase the series to kvm/next branch
> * move the FW error enum definition in include/uapi/linux/psp-sev.h so that
> both userspace and kernel can share it.
> * (ccp) drop cmd_buf arg from sev_platform_init()
> * (ccp) apply some cleanup/fixup from Boris
> * (ccp) add some comments in FACTORY_RESET command handling
> * (kvm) some fixup/cleanup from Boris
> * (kvm) acquire the kvm->lock when modifying the sev->regions_list
>
> Changes since v6:
> * (ccp): Extend psp_device structure to track the FW INIT and SHUTDOWN states.
> * (ccp): Init and Uninit SEV FW during module load/unload
> * (ccp): Avoid repeated k*alloc() for init and status command buffer
> * (kvm): Rework DBG command to fix the compilation warning seen with gcc7.x
> * (kvm): Convert the SEV doc in rst format
>
> Changes since v5:
> * split the PSP driver support into multiple patches
> * multiple improvements from Boris
> * remove mem_enc_enabled() ops
>
> Changes since v4:
> * Fixes to address kbuild robot errors
> * Add 'sev' module params to allow enable/disable SEV feature
> * Update documentation
> * Multiple fixes to address v4 feedbacks
> * Some coding style changes to address checkpatch reports
>
> Changes since v3:
> * Re-design the PSP interface support patch
> * Rename the ioctls based on the feedbacks
> * Improve documentation
> * Fix i386 build issues
> * Add LAUNCH_SECRET command
> * Add new Kconfig option to enable SEV support
> * Changes to address v3 feedbacks.
>
> Changes since v2:
> * Add KVM_MEMORY_ENCRYPT_REGISTER/UNREGISTER_RAM ioct to register encrypted
> memory ranges (recommend by Paolo)
> * Extend kvm_x86_ops to provide new memory_encryption_enabled ops
> * Enhance DEBUG DECRYPT/ENCRYPT commands to work with more than one page \
> (recommended by Paolo)
> * Optimize LAUNCH_UPDATE command to reduce the number of calls to AMD-SP driver
> * Changes to address v2 feedbacks
>
>
> Borislav Petkov (1):
> crypto: ccp: Build the AMD secure processor driver only with AMD CPU
> support
>
> Brijesh Singh (34):
> Documentation/virtual/kvm: Add AMD Secure Encrypted Virtualization
> (SEV)
> KVM: SVM: Prepare to reserve asid for SEV guest
> KVM: X86: Extend CPUID range to include new leaf
> KVM: Introduce KVM_MEMORY_ENCRYPT_OP ioctl
> KVM: Introduce KVM_MEMORY_ENCRYPT_{UN,}REG_REGION ioctl
> crypto: ccp: Define SEV userspace ioctl and command id
> crypto: ccp: Define SEV key management command id
> crypto: ccp: Add Platform Security Processor (PSP) device support
> crypto: ccp: Add Secure Encrypted Virtualization (SEV) command support
> crypto: ccp: Implement SEV_FACTORY_RESET ioctl command
> crypto: ccp: Implement SEV_PLATFORM_STATUS ioctl command
> crypto: ccp: Implement SEV_PEK_GEN ioctl command
> crypto: ccp: Implement SEV_PDH_GEN ioctl command
> crypto: ccp: Implement SEV_PEK_CSR ioctl command
> crypto: ccp: Implement SEV_PEK_CERT_IMPORT ioctl command
> crypto: ccp: Implement SEV_PDH_CERT_EXPORT ioctl command
> KVM: X86: Add CONFIG_KVM_AMD_SEV
> KVM: SVM: Reserve ASID range for SEV guest
> KVM: SVM: Add sev module_param
> KVM: Define SEV key management command id
> KVM: SVM: Add KVM_SEV_INIT command
> KVM: SVM: VMRUN should use associated ASID when SEV is enabled
> KVM: SVM: Add support for KVM_SEV_LAUNCH_START command
> KVM: SVM: Add support for KVM_SEV_LAUNCH_UPDATE_DATA command
> KVM: SVM: Add support for KVM_SEV_LAUNCH_MEASURE command
> KVM: SVM: Add support for SEV LAUNCH_FINISH command
> KVM: SVM: Add support for SEV GUEST_STATUS command
> KVM: SVM: Add support for SEV DEBUG_DECRYPT command
> KVM: SVM: Add support for SEV DEBUG_ENCRYPT command
> KVM: SVM: Add support for SEV LAUNCH_SECRET command
> KVM: SVM: Pin guest memory when SEV is active
> KVM: SVM: Clear C-bit from the page fault address
> KVM: SVM: Do not install #UD intercept when SEV is enabled
> KVM: X86: Restart the guest when insn_len is zero and SEV is enabled
>
> Tom Lendacky (3):
> x86/CPU/AMD: Add the Secure Encrypted Virtualization CPU feature
> kvm: svm: prepare for new bit definition in nested_ctl
> kvm: svm: Add SEV feature definitions to KVM
>
> Documentation/virtual/kvm/00-INDEX | 3 +
> .../virtual/kvm/amd-memory-encryption.rst | 247 ++++
> Documentation/virtual/kvm/api.txt | 50 +
> arch/x86/include/asm/cpufeatures.h | 1 +
> arch/x86/include/asm/kvm_host.h | 15 +
> arch/x86/include/asm/msr-index.h | 2 +
> arch/x86/include/asm/svm.h | 3 +
> arch/x86/kernel/cpu/amd.c | 66 +-
> arch/x86/kernel/cpu/scattered.c | 1 +
> arch/x86/kvm/Kconfig | 10 +
> arch/x86/kvm/cpuid.c | 2 +-
> arch/x86/kvm/mmu.c | 10 +
> arch/x86/kvm/svm.c | 1178 +++++++++++++++++++-
> arch/x86/kvm/x86.c | 30 +
> drivers/crypto/ccp/Kconfig | 12 +
> drivers/crypto/ccp/Makefile | 1 +
> drivers/crypto/ccp/psp-dev.c | 805 +++++++++++++
> drivers/crypto/ccp/psp-dev.h | 83 ++
> drivers/crypto/ccp/sp-dev.c | 35 +
> drivers/crypto/ccp/sp-dev.h | 28 +-
> drivers/crypto/ccp/sp-pci.c | 52 +
> include/linux/psp-sev.h | 606 ++++++++++
> include/uapi/linux/kvm.h | 90 ++
> include/uapi/linux/psp-sev.h | 142 +++
> 24 files changed, 3440 insertions(+), 32 deletions(-)
> create mode 100644 Documentation/virtual/kvm/amd-memory-encryption.rst
> create mode 100644 drivers/crypto/ccp/psp-dev.c
> create mode 100644 drivers/crypto/ccp/psp-dev.h
> create mode 100644 include/linux/psp-sev.h
> create mode 100644 include/uapi/linux/psp-sev.h
>

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Next in thread: Brijesh Singh: "Re: [Part2 PATCH v9 00/38] x86: Secure Encrypted Virtualization (AMD)"
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