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Documentation/virtual/kvm: Add AMD Secure Encrypted Virtualization (SEV) 

Create a Documentation entry to describe the AMD Secure Encrypted
Virtualization (SEV) feature.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Borislav Petkov <bp@suse.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: kvm@vger.kernel.org
Cc: x86@kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
This commit is contained in:
Brijesh Singh 2017-12-04 10:57:23 -06:00
parent 4fbd8d194f
commit b38defdb44
2 changed files with 48 additions and 0 deletions
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3
Documentation/virtual/kvm/00-INDEX
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@ -26,3 +26,6 @@ s390-diag.txt
- Diagnose hypercall description (for IBM S/390)
timekeeping.txt
- timekeeping virtualization for x86-based architectures.
amd-memory-encryption.txt
- notes on AMD Secure Encrypted Virtualization feature and SEV firmware
command description

45
Documentation/virtual/kvm/amd-memory-encryption.rst Normal file
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@ -0,0 +1,45 @@
======================================
Secure Encrypted Virtualization (SEV)
======================================
Overview
========
Secure Encrypted Virtualization (SEV) is a feature found on AMD processors.
SEV is an extension to the AMD-V architecture which supports running
virtual machines (VMs) under the control of a hypervisor. When enabled,
the memory contents of a VM will be transparently encrypted with a key
unique to that VM.
The hypervisor can determine the SEV support through the CPUID
instruction. The CPUID function 0x8000001f reports information related
to SEV::
0x8000001f[eax]:
Bit[1] indicates support for SEV
...
[ecx]:
Bits[31:0] Number of encrypted guests supported simultaneously
If support for SEV is present, MSR 0xc001_0010 (MSR_K8_SYSCFG) and MSR 0xc001_0015
(MSR_K7_HWCR) can be used to determine if it can be enabled::
0xc001_0010:
Bit[23] 1 = memory encryption can be enabled
0 = memory encryption can not be enabled
0xc001_0015:
Bit[0] 1 = memory encryption can be enabled
0 = memory encryption can not be enabled
When SEV support is available, it can be enabled in a specific VM by
setting the SEV bit before executing VMRUN.::
VMCB[0x90]:
Bit[1] 1 = SEV is enabled
0 = SEV is disabled
SEV hardware uses ASIDs to associate a memory encryption key with a VM.
Hence, the ASID for the SEV-enabled guests must be from 1 to a maximum value
defined in the CPUID 0x8000001f[ecx] field.