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From: "Lendacky, Thomas" <thomas.lendacky@amd.com>
To: devel@edk2.groups.io
Cc: Jordan Justen <jordan.l.justen@intel.com>,
	Laszlo Ersek <lersek@redhat.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Michael D Kinney <michael.d.kinney@intel.com>,
	Liming Gao <liming.gao@intel.com>,
	Eric Dong <eric.dong@intel.com>, Ray Ni <ray.ni@intel.com>,
	Brijesh Singh <brijesh.singh@amd.com>
Subject: [PATCH v6 24/42] UefiCpuPkg/CpuExceptionHandler: Add support for DR7 Read/Write NAE events
Date: Tue, 24 Mar 2020 12:40:38 -0500	[thread overview]
Message-ID: <b946b170048e610c43c11f5570ce4b10921ae980.1585071656.git.thomas.lendacky@amd.com> (raw)
In-Reply-To: <cover.1585071656.git.thomas.lendacky@amd.com>

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

Under SEV-ES, a DR7 read or write intercept generates a #VC exception.
The #VC handler must provide special support to the guest for this. On
a DR7 write, the #VC handler must cache the value and issue a VMGEXIT
to notify the hypervisor of the write. However, the #VC handler must
not actually set the value of the DR7 register. On a DR7 read, the #VC
handler must return the cached value of the DR7 register to the guest.
VMGEXIT is not invoked for a DR7 register read.

To avoid exception recursion, a #VC exception will not try to read and
push the actual debug registers into the EFI_SYSTEM_CONTEXT_X64 struct
and instead push zeroes. The #VC exception handler does not make use of
the debug registers from saved context.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 .../X64/ArchAMDSevVcHandler.c                 | 68 +++++++++++++++++++
 .../X64/ExceptionHandlerAsm.nasm              | 17 +++++
 2 files changed, 85 insertions(+)

diff --git a/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ArchAMDSevVcHandler.c b/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ArchAMDSevVcHandler.c
index 1fdbb122c35d..cca9481e8900 100644
--- a/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ArchAMDSevVcHandler.c
+++ b/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ArchAMDSevVcHandler.c
@@ -13,6 +13,12 @@
 
 #define CR4_OSXSAVE (1 << 18)
 
+#define DR7_RESET_VALUE 0x400
+typedef struct {
+  BOOLEAN  Dr7Cached;
+  UINT64   Dr7;
+} SEV_ES_PER_CPU_DATA;
+
 typedef enum {
   LongMode64Bit        = 0,
   LongModeCompat32Bit,
@@ -1076,6 +1082,60 @@ RdtscExit (
   return 0;
 }
 
+STATIC
+UINT64
+Dr7WriteExit (
+  GHCB                     *Ghcb,
+  EFI_SYSTEM_CONTEXT_X64   *Regs,
+  SEV_ES_INSTRUCTION_DATA  *InstructionData
+  )
+{
+  SEV_ES_INSTRUCTION_OPCODE_EXT  *Ext = &InstructionData->Ext;
+  SEV_ES_PER_CPU_DATA            *SevEsData = (SEV_ES_PER_CPU_DATA *) (Ghcb + 1);
+  INTN                           *Register;
+  UINT64                         Status;
+
+  DecodeModRm (Regs, InstructionData);
+
+  /* MOV DRn always treats MOD == 3 no matter how encoded */
+  Register = GetRegisterPointer (Regs, Ext->ModRm.Rm);
+
+  /* Using a value of 0 for ExitInfo1 means RAX holds the value */
+  Ghcb->SaveArea.Rax = *Register;
+  GhcbSetRegValid (Ghcb, GhcbRax);
+
+  Status = VmgExit (Ghcb, SvmExitDr7Write, 0, 0);
+  if (Status) {
+    return Status;
+  }
+
+  SevEsData->Dr7 = *Register;
+  SevEsData->Dr7Cached = TRUE;
+
+  return 0;
+}
+
+STATIC
+UINT64
+Dr7ReadExit (
+  GHCB                     *Ghcb,
+  EFI_SYSTEM_CONTEXT_X64   *Regs,
+  SEV_ES_INSTRUCTION_DATA  *InstructionData
+  )
+{
+  SEV_ES_INSTRUCTION_OPCODE_EXT  *Ext = &InstructionData->Ext;
+  SEV_ES_PER_CPU_DATA            *SevEsData = (SEV_ES_PER_CPU_DATA *) (Ghcb + 1);
+  INTN                           *Register;
+
+  DecodeModRm (Regs, InstructionData);
+
+  /* MOV DRn always treats MOD == 3 no matter how encoded */
+  Register = GetRegisterPointer (Regs, Ext->ModRm.Rm);
+  *Register = (SevEsData->Dr7Cached) ? SevEsData->Dr7 : DR7_RESET_VALUE;
+
+  return 0;
+}
+
 UINTN
 DoVcCommon (
   GHCB                *Ghcb,
@@ -1092,6 +1152,14 @@ DoVcCommon (
 
   ExitCode = Regs->ExceptionData;
   switch (ExitCode) {
+  case SvmExitDr7Read:
+    NaeExit = Dr7ReadExit;
+    break;
+
+  case SvmExitDr7Write:
+    NaeExit = Dr7WriteExit;
+    break;
+
   case SvmExitRdtsc:
     NaeExit = RdtscExit;
     break;
diff --git a/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ExceptionHandlerAsm.nasm b/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ExceptionHandlerAsm.nasm
index 19198f273137..26cae56cc5cf 100644
--- a/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ExceptionHandlerAsm.nasm
+++ b/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ExceptionHandlerAsm.nasm
@@ -18,6 +18,8 @@
 ; CommonExceptionHandler()
 ;
 
+%define VC_EXCEPTION 29
+
 extern ASM_PFX(mErrorCodeFlag)    ; Error code flags for exceptions
 extern ASM_PFX(mDoFarReturnFlag)  ; Do far return flag
 extern ASM_PFX(CommonExceptionHandler)
@@ -225,6 +227,9 @@ HasErrorCode:
     push    rax
 
 ;; UINT64  Dr0, Dr1, Dr2, Dr3, Dr6, Dr7;
+    cmp     qword [rbp + 8], VC_EXCEPTION
+    je      VcDebugRegs          ; For SEV-ES (#VC) Debug registers ignored
+
     mov     rax, dr7
     push    rax
     mov     rax, dr6
@@ -237,7 +242,19 @@ HasErrorCode:
     push    rax
     mov     rax, dr0
     push    rax
+    jmp     DrFinish
 
+VcDebugRegs:
+;; UINT64  Dr0, Dr1, Dr2, Dr3, Dr6, Dr7 are skipped for #VC to avoid exception recursion
+    xor     rax, rax
+    push    rax
+    push    rax
+    push    rax
+    push    rax
+    push    rax
+    push    rax
+
+DrFinish:
 ;; FX_SAVE_STATE_X64 FxSaveState;
     sub rsp, 512
     mov rdi, rsp
-- 
2.17.1


  parent reply	other threads:[~2020-03-24 17:41 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-24 17:40 [PATCH v6 00/42] SEV-ES guest support Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 01/42] MdePkg: Create PCDs to be used in support of SEV-ES Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 02/42] MdePkg: Add the MSR definition for the GHCB register Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 03/42] MdePkg: Add a structure definition for the GHCB Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 04/42] MdeModulePkg/DxeIplPeim: Support GHCB pages when creating page tables Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 05/42] MdePkg/BaseLib: Add support for the XGETBV instruction Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 06/42] MdePkg/BaseLib: Add support for the VMGEXIT instruction Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 07/42] UefiCpuPkg: Implement library support for VMGEXIT Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 08/42] OvmfPkg: Prepare OvmfPkg to use the VmgExitLib library Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 09/42] UefiPayloadPkg: Prepare UefiPayloadPkg " Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 10/42] UefiCpuPkg/CpuExceptionHandler: Add base support for the #VC exception Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 11/42] UefiCpuPkg/CpuExceptionHandler: Add support for IOIO_PROT NAE events Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 12/42] UefiCpuPkg/CpuExceptionHandler: Support string IO " Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 13/42] UefiCpuPkg/CpuExceptionHandler: Add support for CPUID " Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 14/42] UefiCpuPkg/CpuExceptionHandler: Add support for MSR_PROT " Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 15/42] UefiCpuPkg/CpuExceptionHandler: Add support for NPF NAE events (MMIO) Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 16/42] UefiCpuPkg/CpuExceptionHandler: Add support for WBINVD NAE events Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 17/42] UefiCpuPkg/CpuExceptionHandler: Add support for RDTSC " Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 18/42] UefiCpuPkg/CpuExceptionHandler: Add support for RDPMC " Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 19/42] UefiCpuPkg/CpuExceptionHandler: Add support for INVD " Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 20/42] UefiCpuPkg/CpuExceptionHandler: Add support for VMMCALL " Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 21/42] UefiCpuPkg/CpuExceptionHandler: Add support for RDTSCP " Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 22/42] UefiCpuPkg/CpuExceptionHandler: Add support for MONITOR/MONITORX " Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 23/42] UefiCpuPkg/CpuExceptionHandler: Add support for MWAIT/MWAITX " Lendacky, Thomas
2020-03-24 17:40 ` Lendacky, Thomas [this message]
2020-03-24 17:40 ` [PATCH v6 25/42] OvmfPkg/MemEncryptSevLib: Add an SEV-ES guest indicator function Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 26/42] OvmfPkg: Add support to perform SEV-ES initialization Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 27/42] OvmfPkg: Create a GHCB page for use during Sec phase Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 28/42] OvmfPkg/PlatformPei: Reserve GHCB-related areas if S3 is supported Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 29/42] OvmfPkg: Create GHCB pages for use during Pei and Dxe phase Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 30/42] OvmfPkg/PlatformPei: Move early GDT into ram when SEV-ES is enabled Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 31/42] UefiCpuPkg: Create an SEV-ES workarea PCD Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 32/42] OvmfPkg: Reserve a page in memory for the SEV-ES usage Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 33/42] OvmfPkg/ResetVector: Add support for a 32-bit SEV check Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 34/42] OvmfPkg/Sec: Add #VC exception handling for Sec phase Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 36/42] OvmfPkg/QemuFlashFvbServicesRuntimeDxe: Bypass flash detection with SEV-ES is enabled Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 37/42] UefiCpuPkg: Add a 16-bit protected mode code segment descriptor Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 38/42] UefiCpuPkg/MpInitLib: Add CPU MP data flag to indicate if SEV-ES is enabled Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 39/42] UefiCpuPkg: Allow AP booting under SEV-ES Lendacky, Thomas
2020-03-24 17:40 ` [PATCH v6 40/42] OvmfPkg: Use the SEV-ES work area for the SEV-ES AP reset vector Lendacky, Thomas
2020-03-24 19:44 ` [PATCH v6 35/42] OvmfPkg/Sec: Enable cache early to speed up booting Lendacky, Thomas
2020-03-24 19:44 ` [PATCH v6 41/42] OvmfPkg: Move the GHCB allocations into reserved memory Lendacky, Thomas
2020-03-24 19:44 ` [PATCH v6 42/42] UefiCpuPkg/MpInitLib: Prepare SEV-ES guest APs for OS use Lendacky, Thomas
2020-03-30 16:53 ` [PATCH v6 00/42] SEV-ES guest support Lendacky, Thomas
2020-03-31  0:47   ` [edk2-devel] " Dong, Eric
2020-04-01 20:42     ` Lendacky, Thomas
2020-04-02  0:12       ` Dong, Eric
     [not found]       ` <1601D84A636A7BFC.25844@groups.io>
2020-04-14 15:30         ` Dong, Eric
2020-04-16 13:46           ` Lendacky, Thomas
2020-04-17  9:10             ` Dong, Eric

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