[edk2-devel] [PATCH v2 05/15] OvmfPkg/MemEncryptSevLib: Save the encryption mask at boot time
Laszlo Ersek
lersek at redhat.com
Thu Jan 7 14:52:56 UTC 2021
On 01/06/21 22:21, Lendacky, Thomas wrote:
> From: Tom Lendacky <thomas.lendacky at amd.com>
>
> BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3108
>
> The early assembler code performs validation for some of the SEV-related
> information, specifically the encryption bit position. To avoid having to
> re-validate the encryption bit position as the system proceeds through its
> boot phases, save the validated encryption bit position in the SEV-ES work
> area for use by later phases.
>
> Cc: Jordan Justen <jordan.l.justen at intel.com>
> Cc: Laszlo Ersek <lersek at redhat.com>
> Cc: Ard Biesheuvel <ard.biesheuvel at arm.com>
> Cc: Brijesh Singh <brijesh.singh at amd.com>
> Signed-off-by: Tom Lendacky <thomas.lendacky at amd.com>
> ---
> OvmfPkg/Include/Library/MemEncryptSevLib.h | 2 ++
> OvmfPkg/ResetVector/Ia32/PageTables64.asm | 10 +++++++++-
> OvmfPkg/ResetVector/ResetVector.nasmb | 1 +
> 3 files changed, 12 insertions(+), 1 deletion(-)
I think if we replaced "MemEncryptSevLib" with "ResetVector" in the
subject line, that would be more precise. If a v3 becomes necessary,
please do that; otherwise I can do the update when I merge v2 (but even
if I forget that, it's not a big deal).
Reviewed-by: Laszlo Ersek <lersek at redhat.com>
Thanks,
Laszlo
>
> diff --git a/OvmfPkg/Include/Library/MemEncryptSevLib.h b/OvmfPkg/Include/Library/MemEncryptSevLib.h
> index dc09c61e58bb..a2c70aa550fe 100644
> --- a/OvmfPkg/Include/Library/MemEncryptSevLib.h
> +++ b/OvmfPkg/Include/Library/MemEncryptSevLib.h
> @@ -29,6 +29,8 @@ typedef struct _SEC_SEV_ES_WORK_AREA {
> UINT8 Reserved1[7];
>
> UINT64 RandomData;
> +
> + UINT64 EncryptionMask;
> } SEC_SEV_ES_WORK_AREA;
>
> /**
> diff --git a/OvmfPkg/ResetVector/Ia32/PageTables64.asm b/OvmfPkg/ResetVector/Ia32/PageTables64.asm
> index a1771dfdec23..5fae8986d9da 100644
> --- a/OvmfPkg/ResetVector/Ia32/PageTables64.asm
> +++ b/OvmfPkg/ResetVector/Ia32/PageTables64.asm
> @@ -145,7 +145,7 @@ GetSevEncBit:
>
> ; The encryption bit position is always above 31
> sub ebx, 32
> - jns SevExit
> + jns SevSaveMask
>
> ; Encryption bit was reported as 31 or below, enter a HLT loop
> SevEncBitLowHlt:
> @@ -153,6 +153,14 @@ SevEncBitLowHlt:
> hlt
> jmp SevEncBitLowHlt
>
> +SevSaveMask:
> + xor edx, edx
> + bts edx, ebx
> +
> + mov dword[SEV_ES_WORK_AREA_ENC_MASK], 0
> + mov dword[SEV_ES_WORK_AREA_ENC_MASK + 4], edx
> + jmp SevExit
> +
> NoSev:
> ;
> ; Perform an SEV-ES sanity check by seeing if a #VC exception occurred.
> diff --git a/OvmfPkg/ResetVector/ResetVector.nasmb b/OvmfPkg/ResetVector/ResetVector.nasmb
> index d3aa87982959..5fbacaed5f9d 100644
> --- a/OvmfPkg/ResetVector/ResetVector.nasmb
> +++ b/OvmfPkg/ResetVector/ResetVector.nasmb
> @@ -74,6 +74,7 @@
> %define GHCB_SIZE (FixedPcdGet32 (PcdOvmfSecGhcbSize))
> %define SEV_ES_WORK_AREA (FixedPcdGet32 (PcdSevEsWorkAreaBase))
> %define SEV_ES_WORK_AREA_RDRAND (FixedPcdGet32 (PcdSevEsWorkAreaBase) + 8)
> + %define SEV_ES_WORK_AREA_ENC_MASK (FixedPcdGet32 (PcdSevEsWorkAreaBase) + 16)
> %define SEV_ES_VC_TOP_OF_STACK (FixedPcdGet32 (PcdOvmfSecPeiTempRamBase) + FixedPcdGet32 (PcdOvmfSecPeiTempRamSize))
> %include "Ia32/Flat32ToFlat64.asm"
> %include "Ia32/PageTables64.asm"
>
-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#69926): https://edk2.groups.io/g/devel/message/69926
Mute This Topic: https://groups.io/mt/79485051/1813853
Group Owner: devel+owner at edk2.groups.io
Unsubscribe: https://edk2.groups.io/g/devel/unsub [edk2-devel-archive at redhat.com]
-=-=-=-=-=-=-=-=-=-=-=-
More information about the edk2-devel-archive
mailing list