audk/OvmfPkg/Library/VmgExitLib
Tom Lendacky 85b8eac59b OvfmPkg/VmgExitLib: Validate #VC MMIO is to un-encrypted memory
BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3108

When SEV-ES is active, and MMIO operation will trigger a #VC and the
VmgExitLib exception handler will process this MMIO operation.

A malicious hypervisor could try to extract information from encrypted
memory by setting a reserved bit in the guests nested page tables for
a non-MMIO area. This can result in the encrypted data being copied into
the GHCB shared buffer area and accessed by the hypervisor.

Prevent this by ensuring that the MMIO source/destination is un-encrypted
memory. For the APIC register space, access is allowed in general.

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <0cf28470ad5e694af45f7f0b35296628f819567d.1610045305.git.thomas.lendacky@amd.com>
2021-01-07 19:34:39 +00:00
..
PeiDxeVmgExitVcHandler.c OvmfPkg/VmgExitLib: Support nested #VCs 2021-01-07 19:34:39 +00:00
SecVmgExitLib.inf OvfmPkg/VmgExitLib: Validate #VC MMIO is to un-encrypted memory 2021-01-07 19:34:39 +00:00
SecVmgExitVcHandler.c OvmfPkg/VmgExitLib: Support nested #VCs 2021-01-07 19:34:39 +00:00
VmgExitLib.c UefiCpuPkg, OvmfPkg: Disable interrupts when using the GHCB 2020-11-10 19:07:55 +00:00
VmgExitLib.inf OvfmPkg/VmgExitLib: Validate #VC MMIO is to un-encrypted memory 2021-01-07 19:34:39 +00:00
VmgExitVcHandler.c OvfmPkg/VmgExitLib: Validate #VC MMIO is to un-encrypted memory 2021-01-07 19:34:39 +00:00
VmgExitVcHandler.h OvmfPkg/VmgExitLib: Support nested #VCs 2021-01-07 19:34:39 +00:00