From 20da7ca42a33d3ef767ce4129f11496af7f67c9f Mon Sep 17 00:00:00 2001 From: Tom Lendacky Date: Wed, 12 Aug 2020 15:21:43 -0500 Subject: [PATCH] UefiCpuPkg/MpInitLib: Prepare SEV-ES guest APs for OS use BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198 Before UEFI transfers control to the OS, it must park the AP. This is done using the AsmRelocateApLoop function to transition into 32-bit non-paging mode. For an SEV-ES guest, a few additional things must be done: - AsmRelocateApLoop must be updated to support SEV-ES. This means performing a VMGEXIT AP Reset Hold instead of an MWAIT or HLT loop. - Since the AP must transition to real mode, a small routine is copied to the WakeupBuffer area. Since the WakeupBuffer will be used by the AP during OS booting, it must be placed in reserved memory. Additionally, the AP stack must be located where it can be accessed in real mode. - Once the AP is in real mode it will transfer control to the destination specified by the OS in the SEV-ES AP Jump Table. The SEV-ES AP Jump Table address is saved by the hypervisor for the OS using the GHCB VMGEXIT AP Jump Table exit code. Cc: Eric Dong Cc: Ray Ni Cc: Laszlo Ersek Reviewed-by: Eric Dong Signed-off-by: Tom Lendacky Regression-tested-by: Laszlo Ersek --- UefiCpuPkg/Library/MpInitLib/DxeMpLib.c | 54 +++++++- .../Library/MpInitLib/Ia32/MpFuncs.nasm | 5 +- UefiCpuPkg/Library/MpInitLib/MpLib.h | 8 +- UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm | 130 ++++++++++++++++-- 4 files changed, 179 insertions(+), 18 deletions(-) diff --git a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c index 9115ff9e3e..2c00d72dde 100644 --- a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c +++ b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c @@ -12,6 +12,7 @@ #include #include #include +#include #include #include @@ -85,6 +86,13 @@ GetWakeupBuffer ( { EFI_STATUS Status; EFI_PHYSICAL_ADDRESS StartAddress; + EFI_MEMORY_TYPE MemoryType; + + if (PcdGetBool (PcdSevEsIsEnabled)) { + MemoryType = EfiReservedMemoryType; + } else { + MemoryType = EfiBootServicesData; + } // // Try to allocate buffer below 1M for waking vector. @@ -97,7 +105,7 @@ GetWakeupBuffer ( StartAddress = 0x88000; Status = gBS->AllocatePages ( AllocateMaxAddress, - EfiBootServicesData, + MemoryType, EFI_SIZE_TO_PAGES (WakeupBufferSize), &StartAddress ); @@ -159,8 +167,10 @@ GetSevEsAPMemory ( VOID ) { - EFI_STATUS Status; - EFI_PHYSICAL_ADDRESS StartAddress; + EFI_STATUS Status; + EFI_PHYSICAL_ADDRESS StartAddress; + MSR_SEV_ES_GHCB_REGISTER Msr; + GHCB *Ghcb; // // Allocate 1 page for AP jump table page @@ -176,6 +186,16 @@ GetSevEsAPMemory ( DEBUG ((DEBUG_INFO, "Dxe: SevEsAPMemory = %lx\n", (UINTN) StartAddress)); + // + // Save the SevEsAPMemory as the AP jump table. + // + Msr.GhcbPhysicalAddress = AsmReadMsr64 (MSR_SEV_ES_GHCB); + Ghcb = Msr.Ghcb; + + VmgInit (Ghcb); + VmgExit (Ghcb, SVM_EXIT_AP_JUMP_TABLE, 0, (UINT64) (UINTN) StartAddress); + VmgDone (Ghcb); + return (UINTN) StartAddress; } @@ -330,17 +350,26 @@ RelocateApLoop ( BOOLEAN MwaitSupport; ASM_RELOCATE_AP_LOOP AsmRelocateApLoopFunc; UINTN ProcessorNumber; + UINTN StackStart; MpInitLibWhoAmI (&ProcessorNumber); CpuMpData = GetCpuMpData (); MwaitSupport = IsMwaitSupport (); + if (CpuMpData->SevEsIsEnabled) { + StackStart = CpuMpData->SevEsAPResetStackStart; + } else { + StackStart = mReservedTopOfApStack; + } AsmRelocateApLoopFunc = (ASM_RELOCATE_AP_LOOP) (UINTN) mReservedApLoopFunc; AsmRelocateApLoopFunc ( MwaitSupport, CpuMpData->ApTargetCState, CpuMpData->PmCodeSegment, - mReservedTopOfApStack - ProcessorNumber * AP_SAFE_STACK_SIZE, - (UINTN) &mNumberToFinish + StackStart - ProcessorNumber * AP_SAFE_STACK_SIZE, + (UINTN) &mNumberToFinish, + CpuMpData->Pm16CodeSegment, + CpuMpData->SevEsAPBuffer, + CpuMpData->WakeupBuffer ); // // It should never reach here @@ -374,6 +403,21 @@ MpInitChangeApLoopCallback ( while (mNumberToFinish > 0) { CpuPause (); } + + if (CpuMpData->SevEsIsEnabled && (CpuMpData->WakeupBuffer != (UINTN) -1)) { + // + // There are APs present. Re-use reserved memory area below 1MB from + // WakeupBuffer as the area to be used for transitioning to 16-bit mode + // in support of booting of the AP by an OS. + // + CopyMem ( + (VOID *) CpuMpData->WakeupBuffer, + (VOID *) (CpuMpData->AddressMap.RendezvousFunnelAddress + + CpuMpData->AddressMap.SwitchToRealPM16ModeOffset), + CpuMpData->AddressMap.SwitchToRealPM16ModeSize + ); + } + DEBUG ((DEBUG_INFO, "%a() done!\n", __FUNCTION__)); } diff --git a/UefiCpuPkg/Library/MpInitLib/Ia32/MpFuncs.nasm b/UefiCpuPkg/Library/MpInitLib/Ia32/MpFuncs.nasm index 309d53bf3b..7e81d24aa6 100644 --- a/UefiCpuPkg/Library/MpInitLib/Ia32/MpFuncs.nasm +++ b/UefiCpuPkg/Library/MpInitLib/Ia32/MpFuncs.nasm @@ -226,7 +226,10 @@ SwitchToRealProcStart: SwitchToRealProcEnd: ;------------------------------------------------------------------------------------- -; AsmRelocateApLoop (MwaitSupport, ApTargetCState, PmCodeSegment, TopOfApStack, CountTofinish); +; AsmRelocateApLoop (MwaitSupport, ApTargetCState, PmCodeSegment, TopOfApStack, CountTofinish, Pm16CodeSegment, SevEsAPJumpTable, WakeupBuffer); +; +; The last three parameters (Pm16CodeSegment, SevEsAPJumpTable and WakeupBuffer) are +; specific to SEV-ES support and are not applicable on IA32. ;------------------------------------------------------------------------------------- global ASM_PFX(AsmRelocateApLoop) ASM_PFX(AsmRelocateApLoop): diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.h b/UefiCpuPkg/Library/MpInitLib/MpLib.h index b1a9d99cb3..02652eaae1 100644 --- a/UefiCpuPkg/Library/MpInitLib/MpLib.h +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.h @@ -293,7 +293,8 @@ struct _CPU_MP_DATA { UINT64 GhcbBase; }; -#define AP_RESET_STACK_SIZE 64 +#define AP_SAFE_STACK_SIZE 128 +#define AP_RESET_STACK_SIZE AP_SAFE_STACK_SIZE #pragma pack(1) @@ -350,7 +351,10 @@ VOID IN UINTN ApTargetCState, IN UINTN PmCodeSegment, IN UINTN TopOfApStack, - IN UINTN NumberToFinish + IN UINTN NumberToFinish, + IN UINTN Pm16CodeSegment, + IN UINTN SevEsAPJumpTable, + IN UINTN WakeupBuffer ); /** diff --git a/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm b/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm index 6956b408d0..5d30f35b20 100644 --- a/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm +++ b/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm @@ -465,6 +465,10 @@ BITS 16 ; - IP for Real Mode (two bytes) ; - CS for Real Mode (two bytes) ; + ; This label is also used with AsmRelocateApLoop. During MP finalization, + ; the code from PM16Mode to SwitchToRealProcEnd is copied to the start of + ; the WakeupBuffer, allowing a parked AP to be booted by an OS. + ; PM16Mode: mov eax, cr0 ; Read CR0 btr eax, 0 ; Set PE=0 @@ -487,32 +491,96 @@ PM16Mode: SwitchToRealProcEnd: ;------------------------------------------------------------------------------------- -; AsmRelocateApLoop (MwaitSupport, ApTargetCState, PmCodeSegment, TopOfApStack, CountTofinish); +; AsmRelocateApLoop (MwaitSupport, ApTargetCState, PmCodeSegment, TopOfApStack, CountTofinish, Pm16CodeSegment, SevEsAPJumpTable, WakeupBuffer); ;------------------------------------------------------------------------------------- global ASM_PFX(AsmRelocateApLoop) ASM_PFX(AsmRelocateApLoop): AsmRelocateApLoopStart: BITS 64 + cmp qword [rsp + 56], 0 ; SevEsAPJumpTable + je NoSevEs + + ; + ; Perform some SEV-ES related setup before leaving 64-bit mode + ; + push rcx + push rdx + + ; + ; Get the RDX reset value using CPUID + ; + mov rax, 1 + cpuid + mov rsi, rax ; Save off the reset value for RDX + + ; + ; Prepare the GHCB for the AP_HLT_LOOP VMGEXIT call + ; - Must be done while in 64-bit long mode so that writes to + ; the GHCB memory will be unencrypted. + ; - No NAE events can be generated once this is set otherwise + ; the AP_RESET_HOLD SW_EXITCODE will be overwritten. + ; + mov rcx, 0xc0010130 + rdmsr ; Retrieve current GHCB address + shl rdx, 32 + or rdx, rax + + mov rdi, rdx + xor rax, rax + mov rcx, 0x800 + shr rcx, 3 + rep stosq ; Clear the GHCB + + mov rax, 0x80000004 ; VMGEXIT AP_RESET_HOLD + mov [rdx + 0x390], rax + + pop rdx + pop rcx + +NoSevEs: cli ; Disable interrupt before switching to 32-bit mode mov rax, [rsp + 40] ; CountTofinish lock dec dword [rax] ; (*CountTofinish)-- - mov rsp, r9 - push rcx - push rdx - lea rsi, [PmEntry] ; rsi <- The start address of transition code + mov r10, [rsp + 48] ; Pm16CodeSegment + mov rax, [rsp + 56] ; SevEsAPJumpTable + mov rbx, [rsp + 64] ; WakeupBuffer + mov rsp, r9 ; TopOfApStack + + push rax ; Save SevEsAPJumpTable + push rbx ; Save WakeupBuffer + push r10 ; Save Pm16CodeSegment + push rcx ; Save MwaitSupport + push rdx ; Save ApTargetCState + + lea rax, [PmEntry] ; rax <- The start address of transition code push r8 - push rsi - DB 0x48 - retf + push rax + + ; + ; Clear R8 - R15, for reset, before going into 32-bit mode + ; + xor r8, r8 + xor r9, r9 + xor r10, r10 + xor r11, r11 + xor r12, r12 + xor r13, r13 + xor r14, r14 + xor r15, r15 + + ; + ; Far return into 32-bit mode + ; +o64 retf + BITS 32 PmEntry: mov eax, cr0 btr eax, 31 ; Clear CR0.PG mov cr0, eax ; Disable paging and caches - mov ebx, edx ; Save EntryPoint to rbx, for rdmsr will overwrite rdx mov ecx, 0xc0000080 rdmsr and ah, ~ 1 ; Clear LME @@ -525,6 +593,8 @@ PmEntry: add esp, 4 pop ecx, add esp, 4 + +MwaitCheck: cmp cl, 1 ; Check mwait-monitor support jnz HltLoop mov ebx, edx ; Save C-State to ebx @@ -538,10 +608,50 @@ MwaitLoop: shl eax, 4 mwait jmp MwaitLoop + HltLoop: + pop edx ; PM16CodeSegment + add esp, 4 + pop ebx ; WakeupBuffer + add esp, 4 + pop eax ; SevEsAPJumpTable + add esp, 4 + cmp eax, 0 ; Check for SEV-ES + je DoHlt + + cli + ; + ; SEV-ES is enabled, use VMGEXIT (GHCB information already + ; set by caller) + ; +BITS 64 + rep vmmcall +BITS 32 + + ; + ; Back from VMGEXIT AP_HLT_LOOP + ; Push the FLAGS/CS/IP values to use + ; + push word 0x0002 ; EFLAGS + xor ecx, ecx + mov cx, [eax + 2] ; CS + push cx + mov cx, [eax] ; IP + push cx + push word 0x0000 ; For alignment, will be discarded + + push edx + push ebx + + mov edx, esi ; Restore RDX reset value + + retf + +DoHlt: cli hlt - jmp HltLoop + jmp DoHlt + BITS 64 AsmRelocateApLoopEnd: -- 2.39.2