[edk2-devel] [PATCH v3 4/6] OvmfPkg: create a SEV secret area in the AmdSev memfd
Laszlo Ersek
lersek at redhat.com
Thu Dec 3 08:42:30 UTC 2020
On 11/30/20 21:28, James Bottomley wrote:
> SEV needs an area to place an injected secret where OVMF can find it
> and pass it up as a ConfigurationTable. This patch implements the
> area itself as an addition to the SEV enhanced reset vector table using
> an additional guid (4c2eb361-7d9b-4cc3-8081-127c90d3d294).
>
> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3077
> Signed-off-by: James Bottomley <jejb at linux.ibm.com>
> Reviewed-by: Laszlo Ersek <lersek at redhat.com>
>
> ---
>
> v2: move guid to OVMF token space, separate patches
> v3: comment rewording
>
> SEV Secret
> ---
> OvmfPkg/OvmfPkg.dec | 6 ++++++
> OvmfPkg/ResetVector/ResetVector.inf | 4 ++++
> OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm | 19 +++++++++++++++++++
> OvmfPkg/ResetVector/ResetVector.nasmb | 2 ++
> 4 files changed, 31 insertions(+)
>
> diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
> index 3fbf7a0ee1a4..7d27f8e16040 100644
> --- a/OvmfPkg/OvmfPkg.dec
> +++ b/OvmfPkg/OvmfPkg.dec
> @@ -304,6 +304,12 @@ [PcdsFixedAtBuild]
> gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbBase|0|UINT32|0x40
> gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbSize|0|UINT32|0x41
>
> + ## The base address and size of the SEV Launch Secret Area provisioned
> + # after remote attestation. If this is set in the .fdf, the platform
> + # is responsible for protecting the area from DXE phase overwrites.
> + gUefiOvmfPkgTokenSpaceGuid.PcdSevLaunchSecretBase|0x0|UINT32|0x42
> + gUefiOvmfPkgTokenSpaceGuid.PcdSevLaunchSecretSize|0x0|UINT32|0x43
> +
> [PcdsDynamic, PcdsDynamicEx]
> gUefiOvmfPkgTokenSpaceGuid.PcdEmuVariableEvent|0|UINT64|2
> gUefiOvmfPkgTokenSpaceGuid.PcdOvmfFlashVariablesEnable|FALSE|BOOLEAN|0x10
> diff --git a/OvmfPkg/ResetVector/ResetVector.inf b/OvmfPkg/ResetVector/ResetVector.inf
> index a53ae6c194ae..dc38f68919cd 100644
> --- a/OvmfPkg/ResetVector/ResetVector.inf
> +++ b/OvmfPkg/ResetVector/ResetVector.inf
> @@ -43,3 +43,7 @@ [Pcd]
> gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPageTablesSize
> gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamBase
> gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamSize
> +
> +[FixedPcd]
> + gUefiOvmfPkgTokenSpaceGuid.PcdSevLaunchSecretBase
> + gUefiOvmfPkgTokenSpaceGuid.PcdSevLaunchSecretSize
> diff --git a/OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm b/OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm
> index 9e0a74fddfc1..5c6df5ee1a31 100644
> --- a/OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm
> +++ b/OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm
> @@ -47,6 +47,25 @@ TIMES (15 - ((guidedStructureEnd - guidedStructureStart + 15) % 16)) DB 0
> ;
> guidedStructureStart:
>
> +;
> +; SEV Secret block
> +;
> +; This describes the guest ram area where the hypervisor may should
> +; inject the secret. The data format is:
> +;
> +; base physical address (32 bit word)
> +; table length (32 bit word)
> +;
> +; GUID (SEV secret block): 4c2eb361-7d9b-4cc3-8081-127c90d3d294
> +;
(1) s/may should/should/, but we can fix this up at merge.
The syntax updates look great otherwise, so my R-b stands.
Thanks!
Laszlo
> +sevSecretBlockStart:
> + DD SEV_LAUNCH_SECRET_BASE
> + DD SEV_LAUNCH_SECRET_SIZE
> + DW sevSecretBlockEnd - sevSecretBlockStart
> + DB 0x61, 0xB3, 0x2E, 0x4C, 0x9B, 0x7D, 0xC3, 0x4C
> + DB 0x80, 0x81, 0x12, 0x7C, 0x90, 0xD3, 0xD2, 0x94
> +sevSecretBlockEnd:
> +
> ;
> ; SEV-ES Processor Reset support
> ;
> diff --git a/OvmfPkg/ResetVector/ResetVector.nasmb b/OvmfPkg/ResetVector/ResetVector.nasmb
> index 4913b379a993..c5e0fe93abf4 100644
> --- a/OvmfPkg/ResetVector/ResetVector.nasmb
> +++ b/OvmfPkg/ResetVector/ResetVector.nasmb
> @@ -83,5 +83,7 @@
> %include "Main.asm"
>
> %define SEV_ES_AP_RESET_IP FixedPcdGet32 (PcdSevEsWorkAreaBase)
> + %define SEV_LAUNCH_SECRET_BASE FixedPcdGet32 (PcdSevLaunchSecretBase)
> + %define SEV_LAUNCH_SECRET_SIZE FixedPcdGet32 (PcdSevLaunchSecretSize)
> %include "Ia16/ResetVectorVtf0.asm"
>
>
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