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OvmfPkg/ResetVector: convert SEV-ES Reset Block structure to be GUIDed 

Convert the current ES reset block structure to an extensible guid
based structure by appending a header and length, which allow for
multiple guid based data packets to be inserted.

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3077
Signed-off-by: James Bottomley <jejb@linux.ibm.com>
Message-Id: <20201130202819.3910-2-jejb@linux.ibm.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
This commit is contained in:
James Bottomley 2020-11-30 12:28:14 -08:00 committed by mergify[bot]
parent ef3e73c6a0
commit ae1ef911a9
1 changed files with 40 additions and 11 deletions
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51
OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm
View File

@ -25,21 +25,40 @@ ALIGN 16
TIMES (0x1000 - ($ - EndOfPageTables) - 0x20) DB 0
%endif
;
; Padding to ensure first guid starts at 0xffffffd0
;
TIMES (15 - ((guidedStructureEnd - guidedStructureStart + 15) % 16)) DB 0
; GUIDed structure. To traverse this you should first verify the
; presence of the table footer guid
; (96b582de-1fb2-45f7-baea-a366c55a082d) at 0xffffffd0. If that
; is found, the two bytes at 0xffffffce are the entire table length.
;
; The table is composed of structures with the form:
;
; Data (arbitrary bytes identified by guid)
; length from start of data to end of guid (2 bytes)
; guid (16 bytes)
;
; so work back from the footer using the length to traverse until you
; either find the guid you're looking for or run off the beginning of
; the table.
;
guidedStructureStart:
;
; SEV-ES Processor Reset support
;
; sevEsResetBlock:
; For the initial boot of an AP under SEV-ES, the "reset" RIP must be
; programmed to the RAM area defined by SEV_ES_AP_RESET_IP. A known offset
; and GUID will be used to locate this block in the firmware and extract
; the build time RIP value. The GUID must always be 48 bytes from the
; end of the firmware.
; programmed to the RAM area defined by SEV_ES_AP_RESET_IP. The data
; format is:
;
; 0xffffffca (-0x36) - IP value
; 0xffffffcc (-0x34) - CS segment base [31:16]
; 0xffffffce (-0x32) - Size of the SEV-ES reset block
; 0xffffffd0 (-0x30) - SEV-ES reset block GUID
; (00f771de-1a7e-4fcb-890e-68c77e2fb44e)
; IP value [0:15]
; CS segment base [31:16]
;
; GUID (SEV-ES reset block): 00f771de-1a7e-4fcb-890e-68c77e2fb44e
;
; A hypervisor reads the CS segement base and IP value. The CS segment base
; value represents the high order 16-bits of the CS segment base, so the
@ -48,8 +67,6 @@ ALIGN 16
; program the EIP register with the IP value as read.
;
TIMES (32 - (sevEsResetBlockEnd - sevEsResetBlockStart)) DB 0
sevEsResetBlockStart:
DD SEV_ES_AP_RESET_IP
DW sevEsResetBlockEnd - sevEsResetBlockStart
@ -57,6 +74,18 @@ sevEsResetBlockStart:
DB 0x89, 0x0E, 0x68, 0xC7, 0x7E, 0x2F, 0xB4, 0x4E
sevEsResetBlockEnd:
;
; Table footer:
;
; length of whole table (16 bit word)
; GUID (table footer): 96b582de-1fb2-45f7-baea-a366c55a082d
;
DW guidedStructureEnd - guidedStructureStart
DB 0xDE, 0x82, 0xB5, 0x96, 0xB2, 0x1F, 0xF7, 0x45
DB 0xBA, 0xEA, 0xA3, 0x66, 0xC5, 0x5A, 0x08, 0x2D
guidedStructureEnd:
ALIGN 16
applicationProcessorEntryPoint: