[RFC PATCH v3 37/43] OvmfPkg: Reserve a page in memory for the SEV-ES AP reset vector

["Lendacky, Thomas" <thomas.lendacky@amd.com>]

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198

Reserve a fixed area of memory for the SEV-ES AP reset vector and set
the fixed PCD, PcdSevEsResetRipBase, to this value.

A hypervisor is not allowed to update an SEV-ES guest's register state,
so when booting an SEV-ES guest AP, the hypervisor is not allowed to
set the RIP to the guest requested value. Instead an SEV-ES AP must be
re-directed from within the guest to the actual requested staring location
as specified in the INIT-SIPI-SIPI sequence.

Provide reset vector code that contains support to jump to the desired
RIP location after having been started. This is required for only the
very first AP reset.

This new reset vector code is used in place of the original code because
of the include path order set in OvmfPkg/ResetVector/ResetVector.inf
under "[BuildOptions]".

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 OvmfPkg/OvmfPkgX64.fdf                       |  3 +
 OvmfPkg/ResetVector/ResetVector.inf          |  2 +
 OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm | 94 ++++++++++++++++++++
 OvmfPkg/ResetVector/ResetVector.nasmb        |  1 +
 4 files changed, 100 insertions(+)
 create mode 100644 OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm

diff --git a/OvmfPkg/OvmfPkgX64.fdf b/OvmfPkg/OvmfPkgX64.fdf
index 973b19fdbf19..b7618b376430 100644
--- a/OvmfPkg/OvmfPkgX64.fdf
+++ b/OvmfPkg/OvmfPkgX64.fdf
@@ -82,6 +82,9 @@ [FD.MEMFD]
 0x009000|0x002000
 gEfiMdeModulePkgTokenSpaceGuid.PcdSecGhcbBase|gEfiMdeModulePkgTokenSpaceGuid.PcdSecGhcbSize
 
+0x00B000|0x001000
+gUefiCpuPkgTokenSpaceGuid.PcdSevEsResetRipBase|gUefiCpuPkgTokenSpaceGuid.PcdSevEsResetRipSize
+
 0x010000|0x010000
 gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamSize
 
diff --git a/OvmfPkg/ResetVector/ResetVector.inf b/OvmfPkg/ResetVector/ResetVector.inf
index 266c5fc5c8b3..284f03c4fb1e 100644
--- a/OvmfPkg/ResetVector/ResetVector.inf
+++ b/OvmfPkg/ResetVector/ResetVector.inf
@@ -36,6 +36,8 @@ [BuildOptions]
 [Pcd]
   gEfiMdeModulePkgTokenSpaceGuid.PcdSecGhcbBase
   gEfiMdeModulePkgTokenSpaceGuid.PcdSecGhcbSize
+  gUefiCpuPkgTokenSpaceGuid.PcdSevEsResetRipBase
+  gUefiCpuPkgTokenSpaceGuid.PcdSevEsResetRipSize
   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPageTablesBase
   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPageTablesSize
   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamBase
diff --git a/OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm b/OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm
new file mode 100644
index 000000000000..2a3c9bafb451
--- /dev/null
+++ b/OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm
@@ -0,0 +1,94 @@
+;------------------------------------------------------------------------------
+; @file
+; First code executed by processor after resetting.
+; Derived from UefiCpuPkg/ResetVector/Vtf0/Ia16/ResetVectorVtf0.asm
+;
+; Copyright (c) 2008 - 2014, Intel Corporation. All rights reserved.<BR>
+; SPDX-License-Identifier: BSD-2-Clause-Patent
+;
+;------------------------------------------------------------------------------
+
+BITS    16
+
+ALIGN   16
+
+;
+; Pad the image size to 4k when page tables are in VTF0
+;
+; If the VTF0 image has page tables built in, then we need to make
+; sure the end of VTF0 is 4k above where the page tables end.
+;
+; This is required so the page tables will be 4k aligned when VTF0 is
+; located just below 0x100000000 (4GB) in the firmware device.
+;
+%ifdef ALIGN_TOP_TO_4K_FOR_PAGING
+    TIMES (0x1000 - ($ - EndOfPageTables) - 0x20) DB 0
+%endif
+
+;
+; 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_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.
+;
+;   0xffffffca (-0x36) - IP value
+;   0xffffffcc (-0x34) - CS selector value
+;   0xffffffce (-0x32) - Size of SEV-ES reset block
+;   0xffffffd0 (-0x30) - SEV-ES reset block GUID
+;                        (00f771de-1a7e-4fcb-890e-68c77e2fb44e)
+;
+
+TIMES (32 - (sevEsResetBlockEnd - sevEsResetBlockStart)) DB 0
+
+sevEsResetBlockStart:
+    DD      SEV_ES_RESET_IP
+    DW      sevEsResetBlockEnd - sevEsResetBlockStart
+    DB      0xDE, 0x71, 0xF7, 0x00, 0x7E, 0x1A, 0xCB, 0x4F
+    DB      0x89, 0x0E, 0x68, 0xC7, 0x7E, 0x2F, 0xB4, 0x4E
+sevEsResetBlockEnd:
+
+ALIGN   16
+
+applicationProcessorEntryPoint:
+;
+; Application Processors entry point
+;
+; GenFv generates code aligned on a 4k boundary which will jump to this
+; location.  (0xffffffe0)  This allows the Local APIC Startup IPI to be
+; used to wake up the application processors.
+;
+    jmp     EarlyApInitReal16
+
+ALIGN   8
+
+    DD      0
+
+;
+; The VTF signature
+;
+; VTF-0 means that the VTF (Volume Top File) code does not require
+; any fixups.
+;
+vtfSignature:
+    DB      'V', 'T', 'F', 0
+
+ALIGN   16
+
+resetVector:
+;
+; Reset Vector
+;
+; This is where the processor will begin execution
+;
+    nop
+    nop
+    jmp     EarlyBspInitReal16
+
+ALIGN   16
+
+fourGigabytes:
+
diff --git a/OvmfPkg/ResetVector/ResetVector.nasmb b/OvmfPkg/ResetVector/ResetVector.nasmb
index 708bbda6208f..2bf14681099e 100644
--- a/OvmfPkg/ResetVector/ResetVector.nasmb
+++ b/OvmfPkg/ResetVector/ResetVector.nasmb
@@ -81,5 +81,6 @@
 
 %include "Main.asm"
 
+  %define SEV_ES_RESET_IP  FixedPcdGet32 (PcdSevEsResetRipBase)
 %include "Ia16/ResetVectorVtf0.asm"
 
-- 
2.17.1