From: "Lendacky, Thomas" <thomas.lendacky@amd.com>
To: "devel@edk2.groups.io" <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>,
"Singh, Brijesh" <brijesh.singh@amd.com>
Subject: [RFC PATCH 24/28] UefiCpuPkg/CpuExceptionHandler: Add support for DR7 Read/Write NAE events
Date: Mon, 19 Aug 2019 21:36:18 +0000 [thread overview]
Message-ID: <c9415d7b4901305226774c7f0ccce295066452bc.1566250534.git.thomas.lendacky@amd.com> (raw)
In-Reply-To: <cover.1566250534.git.thomas.lendacky@amd.com>
From: Tom Lendacky <thomas.lendacky@amd.com>
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.
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
.../X64/AMDSevVcCommon.c | 68 +++++++++++++++++++
.../X64/ExceptionHandlerAsm.nasm | 15 ++++
2 files changed, 83 insertions(+)
diff --git a/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/AMDSevVcCommon.c b/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/AMDSevVcCommon.c
index 43a3a116af5d..8d7633b15e25 100644
--- a/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/AMDSevVcCommon.c
+++ b/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/AMDSevVcCommon.c
@@ -5,6 +5,12 @@
#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,
@@ -1043,6 +1049,60 @@ RdtscExit (
return 0;
}
+STATIC
+UINTN
+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;
+ UINTN 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
+UINTN
+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,
@@ -1059,6 +1119,14 @@ 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 4db1a09f2881..d23af671df66 100644
--- a/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ExceptionHandlerAsm.nasm
+++ b/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ExceptionHandlerAsm.nasm
@@ -223,6 +223,9 @@ HasErrorCode:
push rax
;; UINT64 Dr0, Dr1, Dr2, Dr3, Dr6, Dr7;
+ cmp qword [rbp + 8], 29
+ je VcDebugRegs ; For SEV-ES (#VC) Debug registers ignored
+
mov rax, dr7
push rax
mov rax, dr6
@@ -235,7 +238,19 @@ 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
next prev parent reply other threads:[~2019-08-19 21:36 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-19 21:35 [RFC PATCH 00/28] SEV-ES guest support thomas.lendacky
2019-08-19 21:35 ` [RFC PATCH 01/28] OvmfPkg/Sec: Enable cache early to speed up booting Lendacky, Thomas
2019-08-21 14:21 ` [edk2-devel] " Laszlo Ersek
2019-08-21 21:25 ` Lendacky, Thomas
2019-08-21 21:51 ` Jordan Justen
2019-08-22 13:46 ` Laszlo Ersek
2019-08-22 20:44 ` Jordan Justen
2019-08-23 13:32 ` Laszlo Ersek
2019-08-19 21:35 ` [RFC PATCH 02/28] OvmfPkg/ResetVector: Add support for a 32-bit SEV check Lendacky, Thomas
2019-08-19 21:35 ` [RFC PATCH 03/28] OvmfPkg/MemEncryptSevLib: Add an SEV-ES guest indicator function Lendacky, Thomas
2019-08-19 21:35 ` [RFC PATCH 04/28] OvmfPkg: Create a GHCB page for use during Sec phase Lendacky, Thomas
2019-08-21 14:25 ` [edk2-devel] " Laszlo Ersek
2019-08-21 21:29 ` Lendacky, Thomas
2019-08-19 21:35 ` [RFC PATCH 05/28] OvmfPkg: Create GHCB pages for use during Pei and Dxe phase Lendacky, Thomas
2019-08-21 14:31 ` [edk2-devel] " Laszlo Ersek
2019-08-21 21:42 ` Lendacky, Thomas
2019-08-22 14:12 ` Laszlo Ersek
2019-08-22 15:24 ` Lendacky, Thomas
2019-08-23 13:26 ` Laszlo Ersek
2019-08-19 21:35 ` [RFC PATCH 06/28] OvmfPkg: A per-CPU variable area for #VC usage Lendacky, Thomas
2019-08-19 21:35 ` [RFC PATCH 07/28] OvmfPkg/PlatformPei: Move early GDT into ram when SEV-ES is enabled Lendacky, Thomas
2019-08-21 15:44 ` [edk2-devel] " Laszlo Ersek
2019-08-19 21:35 ` [RFC PATCH 08/28] MdePkg/BaseLib: Implement the VMGEXIT support Lendacky, Thomas
2019-08-19 21:47 ` Ni, Ray
2019-08-19 22:25 ` Lendacky, Thomas
2019-08-19 21:35 ` [RFC PATCH 09/28] UefiCpuPkg/CpuExceptionHandler: Add base support for the #VC exception Lendacky, Thomas
2019-08-19 21:35 ` [RFC PATCH 10/28] UefiCpuPkg/CpuExceptionHandler: Add base #VC exception handling support for Sec phase Lendacky, Thomas
2019-08-19 21:36 ` [RFC PATCH 11/28] UefiCpuPkg/CpuExceptionHandler: Add support for IOIO_PROT NAE events Lendacky, Thomas
2019-08-19 21:36 ` [RFC PATCH 12/28] UefiCpuPkg/CpuExceptionHandler: Support string IO " Lendacky, Thomas
2019-08-19 21:36 ` [RFC PATCH 13/28] UefiCpuPkg/CpuExceptionHandler: Add support for CPUID " Lendacky, Thomas
2019-08-19 21:36 ` [RFC PATCH 14/28] UefiCpuPkg/CpuExceptionHandler: Add support for MSR_PROT " Lendacky, Thomas
2019-08-19 21:36 ` [RFC PATCH 15/28] UefiCpuPkg/CpuExceptionHandler: Add support for NPF NAE events (MMIO) Lendacky, Thomas
2019-08-19 21:36 ` [RFC PATCH 16/28] UefiCpuPkg/CpuExceptionHandler: Add support for WBINVD NAE events Lendacky, Thomas
2019-08-19 21:36 ` [RFC PATCH 17/28] UefiCpuPkg/CpuExceptionHandler: Add support for RDTSC " Lendacky, Thomas
2019-08-19 21:36 ` [RFC PATCH 18/28] UefiCpuPkg/CpuExceptionHandler: Add support for RDPMC " Lendacky, Thomas
2019-08-19 21:36 ` [RFC PATCH 19/28] UefiCpuPkg/CpuExceptionHandler: Add support for INVD " Lendacky, Thomas
2019-08-19 21:36 ` [RFC PATCH 20/28] UefiCpuPkg/CpuExceptionHandler: Add support for VMMCALL " Lendacky, Thomas
2019-08-19 21:36 ` [RFC PATCH 21/28] UefiCpuPkg/CpuExceptionHandler: Add support for RDTSCP " Lendacky, Thomas
2019-08-19 21:36 ` [RFC PATCH 22/28] UefiCpuPkg/CpuExceptionHandler: Add support for MONITOR/MONITORX " Lendacky, Thomas
2019-08-19 21:36 ` [RFC PATCH 23/28] UefiCpuPkg/CpuExceptionHandler: Add support for MWAIT/MWAITX " Lendacky, Thomas
2019-08-19 21:36 ` Lendacky, Thomas [this message]
2019-08-19 21:36 ` [RFC PATCH 25/28] UefiCpuPkg/CpuExceptionHandler: Add base #VC exception handling support for Pei/Dxe phases Lendacky, Thomas
2019-08-19 21:36 ` [RFC PATCH 26/28] UefiCpuPkg/MpInitLib: Update CPU MP data with a flag to indicate if SEV-ES is active Lendacky, Thomas
2019-08-19 21:36 ` [RFC PATCH 27/28] UefiCpuPkg/MpInitLib: Allow AP booting under SEV-ES Lendacky, Thomas
2019-08-19 21:36 ` [RFC PATCH 28/28] UefiCpuPkg/MpInitLib: Introduce an MP finalization routine to support SEV-ES Lendacky, Thomas
2019-08-21 14:17 ` [edk2-devel] [RFC PATCH 00/28] SEV-ES guest support Laszlo Ersek
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