From ae1ef911a9cd1b6b6163e445901bec5e68ca24a9 Mon Sep 17 00:00:00 2001 From: James Bottomley Date: Mon, 30 Nov 2020 12:28:14 -0800 Subject: 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 Message-Id: <20201130202819.3910-2-jejb@linux.ibm.com> Acked-by: Ard Biesheuvel Reviewed-by: Laszlo Ersek --- OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm | 51 ++++++++++++++++++++++------ 1 file changed, 40 insertions(+), 11 deletions(-) (limited to 'OvmfPkg') diff --git a/OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm b/OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm index 980e0138e7..9e0a74fddf 100644 --- a/OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm +++ b/OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm @@ -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: -- cgit v1.2.3