Reviewed-by: Eric Dong <eric.d...@intel.com> > -----Original Message----- > From: Tom Lendacky <thomas.lenda...@amd.com> > Sent: Tuesday, July 14, 2020 10:38 PM > To: devel@edk2.groups.io > Cc: Brijesh Singh <brijesh.si...@amd.com>; Ard Biesheuvel > <ard.biesheu...@arm.com>; Dong, Eric <eric.d...@intel.com>; Justen, > Jordan L <jordan.l.jus...@intel.com>; Laszlo Ersek <ler...@redhat.com>; > Gao, Liming <liming....@intel.com>; Kinney, Michael D > <michael.d.kin...@intel.com>; Ni, Ray <ray...@intel.com> > Subject: [PATCH v10 45/46] UefiCpuPkg/MpInitLib: Prepare SEV-ES guest APs > for OS use > > From: Tom Lendacky <thomas.lenda...@amd.com> > > 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 <eric.d...@intel.com> > Cc: Ray Ni <ray...@intel.com> > Cc: Laszlo Ersek <ler...@redhat.com> > Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com> > --- > UefiCpuPkg/Library/MpInitLib/MpLib.h | 8 +- > UefiCpuPkg/Library/MpInitLib/DxeMpLib.c | 54 +++++++- > UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm | 131 > ++++++++++++++++-- > 3 files changed, 175 insertions(+), 18 deletions(-) > > diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.h > b/UefiCpuPkg/Library/MpInitLib/MpLib.h > index b1a9d99cb3eb..267aa5201c50 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) > > @@ -349,8 +350,11 @@ VOID > IN BOOLEAN MwaitSupport, > IN UINTN ApTargetCState, > IN UINTN PmCodeSegment, > + IN UINTN Pm16CodeSegment, > IN UINTN TopOfApStack, > - IN UINTN NumberToFinish > + IN UINTN NumberToFinish, > + IN UINTN SevEsAPJumpTable, > + IN UINTN WakeupBuffer > ); > > /** > diff --git a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c > b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c > index 9115ff9e3e30..7165bcf3124a 100644 > --- a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c > +++ b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c > @@ -12,6 +12,7 @@ > #include <Library/UefiBootServicesTableLib.h> > #include <Library/DebugAgentLib.h> > #include <Library/DxeServicesTableLib.h> > +#include <Library/VmgExitLib.h> > #include <Register/Amd/Fam17Msr.h> > #include <Register/Amd/Ghcb.h> > > @@ -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 > + CpuMpData->Pm16CodeSegment, > + StackStart - ProcessorNumber * AP_SAFE_STACK_SIZE, > + (UINTN) &mNumberToFinish, > + 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/X64/MpFuncs.nasm > b/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm > index 6956b408d004..3b8ec477b8b3 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 +491,95 @@ PM16Mode: > SwitchToRealProcEnd: > > > ;------------------------------------------------------------------------------------- > -; AsmRelocateApLoop (MwaitSupport, ApTargetCState, PmCodeSegment, > TopOfApStack, CountTofinish); > +; AsmRelocateApLoop (MwaitSupport, ApTargetCState, PmCodeSegment, > +Pm16CodeSegment, TopOfApStack, CountTofinish, SevEsAPJumpTable, > +WakeupBuffer); > > ;------------------------------------------------------------------------------------- > global ASM_PFX(AsmRelocateApLoop) > ASM_PFX(AsmRelocateApLoop): > AsmRelocateApLoopStart: > BITS 64 > + cmp qword [rsp + 56], 0 > + 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 > + mov rax, [rsp + 48] ; CountTofinish > lock dec dword [rax] ; (*CountTofinish)-- > - mov rsp, r9 > - push rcx > - push rdx > > - lea rsi, [PmEntry] ; rsi <- The start address of transition > code > + mov rax, [rsp + 56] ; SevEsAPJumpTable > + mov rbx, [rsp + 64] ; WakeupBuffer > + mov rsp, [rsp + 40] ; TopOfApStack > + > + push rax ; Save SevEsAPJumpTable > + push rbx ; Save WakeupBuffer > + push r9 ; 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 +592,8 @@ 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 +607,50 @@ 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: > > -- > 2.27.0
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