Re: [RFC PATCH 03/14] OvmfPkg/PlatformDxe: Add support for SEV live migration.

["Ashish Kalra" <ashish.kalra@amd.com>]

On Wed, Mar 03, 2021 at 11:47:51AM -0500, Tobin Feldman-Fitzthum wrote:
> 
> On 3/3/21 11:41 AM, Ashish Kalra wrote:
> > Hello Tobin,
> > 
> > You don't need this patch for MH support, this patch is only required
> > for (SEV) slow migration support.
> 
> If the SevLiveMigrationEnabled variable is not set, the bitmap sync does not
> work correctly (bitmap all zeros), at least for the version of the kernel we
> have been using. Since the bitmap will be replaced, this might not be
> necessary in the future but it is for our setup at the moment.
> 

Ok, i remember that GET_PAGE_ENCRYPTION_BITMAP ioctl will not work
correctly.

Thanks,
Ashish

> > 
> > On Tue, Mar 02, 2021 at 03:48:28PM -0500, Tobin Feldman-Fitzthum wrote:
> > > From: Ashish Kalra <ashish.kalra@amd.com>
> > > 
> > > Detect for KVM hypervisor and check for SEV live migration
> > > feature support via KVM_FEATURE_CPUID, if detected setup a new
> > > UEFI enviroment variable to indicate OVMF support for SEV
> > > live migration.
> > > 
> > > Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
> > > ---
> > >   OvmfPkg/OvmfPkg.dec                  |  1 +
> > >   OvmfPkg/PlatformDxe/Platform.inf     |  2 +
> > >   OvmfPkg/Include/Guid/MemEncryptLib.h | 16 +++++
> > >   OvmfPkg/PlatformDxe/PlatformConfig.h |  5 ++
> > >   OvmfPkg/PlatformDxe/AmdSev.c         | 99 ++++++++++++++++++++++++++++
> > >   OvmfPkg/PlatformDxe/Platform.c       |  6 ++
> > >   6 files changed, 129 insertions(+)
> > >   create mode 100644 OvmfPkg/Include/Guid/MemEncryptLib.h
> > >   create mode 100644 OvmfPkg/PlatformDxe/AmdSev.c
> > > 
> > > diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
> > > index 4348bb45c6..4450d78b91 100644
> > > --- a/OvmfPkg/OvmfPkg.dec
> > > +++ b/OvmfPkg/OvmfPkg.dec
> > > @@ -122,6 +122,7 @@
> > >     gQemuKernelLoaderFsMediaGuid          = {0x1428f772, 0xb64a, 0x441e, {0xb8, 0xc3, 0x9e, 0xbd, 0xd7, 0xf8, 0x93, 0xc7}}
> > >     gGrubFileGuid                         = {0xb5ae312c, 0xbc8a, 0x43b1, {0x9c, 0x62, 0xeb, 0xb8, 0x26, 0xdd, 0x5d, 0x07}}
> > >     gConfidentialComputingSecretGuid      = {0xadf956ad, 0xe98c, 0x484c, {0xae, 0x11, 0xb5, 0x1c, 0x7d, 0x33, 0x64, 0x47}}
> > > +  gMemEncryptGuid                       = {0x0cf29b71, 0x9e51, 0x433a, {0xa3, 0xb7, 0x81, 0xf3, 0xab, 0x16, 0xb8, 0x75}}
> > >   [Ppis]
> > >     # PPI whose presence in the PPI database signals that the TPM base address
> > > diff --git a/OvmfPkg/PlatformDxe/Platform.inf b/OvmfPkg/PlatformDxe/Platform.inf
> > > index 14727c1220..2896f0a1d1 100644
> > > --- a/OvmfPkg/PlatformDxe/Platform.inf
> > > +++ b/OvmfPkg/PlatformDxe/Platform.inf
> > > @@ -24,6 +24,7 @@
> > >     PlatformConfig.c
> > >     PlatformConfig.h
> > >     PlatformForms.vfr
> > > +  AmdSev.c
> > >   [Packages]
> > >     MdePkg/MdePkg.dec
> > > @@ -56,6 +57,7 @@
> > >   [Guids]
> > >     gEfiIfrTianoGuid
> > >     gOvmfPlatformConfigGuid
> > > +  gMemEncryptGuid
> > >   [Depex]
> > >     gEfiHiiConfigRoutingProtocolGuid  AND
> > > diff --git a/OvmfPkg/Include/Guid/MemEncryptLib.h b/OvmfPkg/Include/Guid/MemEncryptLib.h
> > > new file mode 100644
> > > index 0000000000..8264a647af
> > > --- /dev/null
> > > +++ b/OvmfPkg/Include/Guid/MemEncryptLib.h
> > > @@ -0,0 +1,16 @@
> > > +/** @file
> > > +  AMD Memory Encryption GUID, define a new GUID for defining
> > > +  new UEFI enviroment variables assocaiated with SEV Memory Encryption.
> > > +  Copyright (c) 2020, AMD Inc. All rights reserved.<BR>
> > > +  SPDX-License-Identifier: BSD-2-Clause-Patent
> > > +**/
> > > +
> > > +#ifndef __MEMENCRYPT_LIB_H__
> > > +#define __MEMENCRYPT_LIB_H__
> > > +
> > > +#define MEMENCRYPT_GUID \
> > > +{0x0cf29b71, 0x9e51, 0x433a, {0xa3, 0xb7, 0x81, 0xf3, 0xab, 0x16, 0xb8, 0x75}}
> > > +
> > > +extern EFI_GUID gMemEncryptGuid;
> > > +
> > > +#endif
> > > diff --git a/OvmfPkg/PlatformDxe/PlatformConfig.h b/OvmfPkg/PlatformDxe/PlatformConfig.h
> > > index 716514da21..4f662aafa4 100644
> > > --- a/OvmfPkg/PlatformDxe/PlatformConfig.h
> > > +++ b/OvmfPkg/PlatformDxe/PlatformConfig.h
> > > @@ -44,6 +44,11 @@ PlatformConfigLoad (
> > >     OUT UINT64          *OptionalElements
> > >     );
> > > +VOID
> > > +AmdSevSetConfig(
> > > +  VOID
> > > +  );
> > > +
> > >   //
> > >   // Feature flags for OptionalElements.
> > >   //
> > > diff --git a/OvmfPkg/PlatformDxe/AmdSev.c b/OvmfPkg/PlatformDxe/AmdSev.c
> > > new file mode 100644
> > > index 0000000000..1f804984b7
> > > --- /dev/null
> > > +++ b/OvmfPkg/PlatformDxe/AmdSev.c
> > > @@ -0,0 +1,99 @@
> > > +/**@file
> > > +  Detect KVM hypervisor support for SEV live migration and if
> > > +  detected, setup a new UEFI enviroment variable indicating
> > > +  OVMF support for SEV live migration.
> > > +  Copyright (c) 2020, Advanced Micro Devices. All rights reserved.<BR>
> > > +  SPDX-License-Identifier: BSD-2-Clause-Patent
> > > +**/
> > > +//
> > > +// The package level header files this module uses
> > > +//
> > > +
> > > +#include <Library/BaseLib.h>
> > > +#include <Library/BaseMemoryLib.h>
> > > +#include <Library/DebugLib.h>
> > > +#include <Library/UefiBootServicesTableLib.h>
> > > +#include <Library/UefiRuntimeServicesTableLib.h>
> > > +#include <Guid/MemEncryptLib.h>
> > > +
> > > +/**
> > > +  Figures out if we are running inside KVM HVM and
> > > +  KVM HVM supports SEV Live Migration feature.
> > > +  @retval TRUE   KVM was detected and Live Migration supported
> > > +  @retval FALSE  KVM was not detected or Live Migration not supported
> > > +**/
> > > +BOOLEAN
> > > +KvmDetectSevLiveMigrationFeature(
> > > +  VOID
> > > +  )
> > > +{
> > > +  UINT8 Signature[13];
> > > +  UINT32 mKvmLeaf = 0;
> > > +  UINT32 RegEax, RegEbx, RegEcx, RegEdx;
> > > +
> > > +  Signature[12] = '\0';
> > > +  for (mKvmLeaf = 0x40000000; mKvmLeaf < 0x40010000; mKvmLeaf += 0x100) {
> > > +    AsmCpuid (mKvmLeaf,
> > > +              NULL,
> > > +              (UINT32 *) &Signature[0],
> > > +              (UINT32 *) &Signature[4],
> > > +              (UINT32 *) &Signature[8]);
> > > +
> > > +    if (!AsciiStrCmp ((CHAR8 *) Signature, "KVMKVMKVM\0\0\0")) {
> > > +   DEBUG ((
> > > +    DEBUG_ERROR,
> > > +    "%a: KVM Detected, signature = %s\n",
> > > +    __FUNCTION__,
> > > +    Signature
> > > +    ));
> > > +
> > > +    RegEax = 0x40000001;
> > > +    RegEcx = 0;
> > > +      AsmCpuid (0x40000001, &RegEax, &RegEbx, &RegEcx, &RegEdx);
> > > +      if (RegEax & (1 << 14)) {
> > > +     DEBUG ((
> > > +    DEBUG_ERROR,
> > > +    "%a: Live Migration feature supported\n",
> > > +    __FUNCTION__
> > > +    ));
> > > +    return TRUE;
> > > +     }
> > > +    }
> > > +  }
> > > +
> > > +  return FALSE;
> > > +}
> > > +
> > > +/**
> > > +  Function checks if SEV Live Migration support is available, if present then it sets
> > > +  a UEFI enviroment variable to be queried later using Runtime services.
> > > +  **/
> > > +VOID
> > > +AmdSevSetConfig(
> > > +  VOID
> > > +  )
> > > +{
> > > +  EFI_STATUS Status;
> > > +  BOOLEAN SevLiveMigrationEnabled;
> > > +
> > > +  SevLiveMigrationEnabled = KvmDetectSevLiveMigrationFeature();
> > > +
> > > +  if (SevLiveMigrationEnabled) {
> > > +   Status = gRT->SetVariable (
> > > +    L"SevLiveMigrationEnabled",
> > > +                &gMemEncryptGuid,
> > > +    EFI_VARIABLE_NON_VOLATILE |
> > > +                EFI_VARIABLE_BOOTSERVICE_ACCESS |
> > > +          EFI_VARIABLE_RUNTIME_ACCESS,
> > > +                sizeof (BOOLEAN),
> > > +                &SevLiveMigrationEnabled
> > > +               );
> > > +
> > > +   DEBUG ((
> > > +    DEBUG_ERROR,
> > > +    "%a: Setting SevLiveMigrationEnabled variable, status = %lx\n",
> > > +    __FUNCTION__,
> > > +    Status
> > > +    ));
> > > +  }
> > > +}
> > > diff --git a/OvmfPkg/PlatformDxe/Platform.c b/OvmfPkg/PlatformDxe/Platform.c
> > > index f2e51960ce..9a19b9f6b1 100644
> > > --- a/OvmfPkg/PlatformDxe/Platform.c
> > > +++ b/OvmfPkg/PlatformDxe/Platform.c
> > > @@ -763,6 +763,12 @@ PlatformInit (
> > >   {
> > >     EFI_STATUS Status;
> > > +  //
> > > +  // Set Amd Sev configuation
> > > +  //
> > > +  AmdSevSetConfig();
> > > +
> > > +
> > >     ExecutePlatformConfig ();
> > >     mConfigAccess.ExtractConfig = &ExtractConfig;
> > > -- 
> > > 2.20.1
> > >