[PATCH v2 0/5] x86/sev-es: Mitigate some HV attack vectors

[Joerg Roedel]

From: Joerg Roedel <jroedel@xxxxxxx>

Hi,

here are some enhancements to the SEV(-ES) code in the Linux kernel to
self-protect it against some newly detected hypervisor attacks. There
are 3 attacks addressed here:

	1) Hypervisor does not present the SEV-enabled bit via CPUID

	2) The Hypervisor presents the wrong C-bit position via CPUID

	3) An encrypted RAM page is mapped as MMIO in the nested
	   page-table, causing #VC exceptions and possible leak of the
	   data to the hypervisor or data/code injection from the
	   Hypervisor.

The attacks are described in more detail in this paper:

	https://arxiv.org/abs/2010.07094

Please review.

Thanks,

	Joerg

Changes to v1:

	- Disable CR4.PGE during C-bit test

	- Do not safe/restore caller-safed registers in
	  set_sev_encryption_mask()

Joerg Roedel (5):
  x86/boot/compressed/64: Introduce sev_status
  x86/boot/compressed/64: Add CPUID sanity check to early #VC handler
  x86/boot/compressed/64: Check SEV encryption in 64-bit boot-path
  x86/head/64: Check SEV encryption before switching to kernel
    page-table
  x86/sev-es: Do not support MMIO to/from encrypted memory

 arch/x86/boot/compressed/ident_map_64.c |  1 +
 arch/x86/boot/compressed/mem_encrypt.S  | 14 +++-
 arch/x86/boot/compressed/misc.h         |  2 +
 arch/x86/kernel/head_64.S               | 14 +++-
 arch/x86/kernel/sev-es-shared.c         | 26 +++++++
 arch/x86/kernel/sev-es.c                | 20 ++++--
 arch/x86/kernel/sev_verify_cbit.S       | 91 +++++++++++++++++++++++++
 arch/x86/mm/mem_encrypt.c               |  1 +
 8 files changed, 160 insertions(+), 9 deletions(-)
 create mode 100644 arch/x86/kernel/sev_verify_cbit.S

-- 
2.28.0