+/**\r
+ Handle an MSR event.\r
+\r
+ Use the VMGEXIT instruction to handle either a RDMSR or WRMSR event.\r
+\r
+ @param[in, out] Ghcb Pointer to the Guest-Hypervisor Communication\r
+ Block\r
+ @param[in, out] Regs x64 processor context\r
+ @param[in] InstructionData Instruction parsing context\r
+\r
+ @retval 0 Event handled successfully\r
+ @return New exception value to propagate\r
+\r
+**/\r
+STATIC\r
+UINT64\r
+MsrExit (\r
+ IN OUT GHCB *Ghcb,\r
+ IN OUT EFI_SYSTEM_CONTEXT_X64 *Regs,\r
+ IN SEV_ES_INSTRUCTION_DATA *InstructionData\r
+ )\r
+{\r
+ UINT64 ExitInfo1, Status;\r
+\r
+ ExitInfo1 = 0;\r
+\r
+ switch (*(InstructionData->OpCodes + 1)) {\r
+ case 0x30: // WRMSR\r
+ ExitInfo1 = 1;\r
+ Ghcb->SaveArea.Rax = Regs->Rax;\r
+ GhcbSetRegValid (Ghcb, GhcbRax);\r
+ Ghcb->SaveArea.Rdx = Regs->Rdx;\r
+ GhcbSetRegValid (Ghcb, GhcbRdx);\r
+ //\r
+ // fall through\r
+ //\r
+ case 0x32: // RDMSR\r
+ Ghcb->SaveArea.Rcx = Regs->Rcx;\r
+ GhcbSetRegValid (Ghcb, GhcbRcx);\r
+ break;\r
+ default:\r
+ return UnsupportedExit (Ghcb, Regs, InstructionData);\r
+ }\r
+\r
+ Status = VmgExit (Ghcb, SVM_EXIT_MSR, ExitInfo1, 0);\r
+ if (Status != 0) {\r
+ return Status;\r
+ }\r
+\r
+ if (ExitInfo1 == 0) {\r
+ if (!GhcbIsRegValid (Ghcb, GhcbRax) ||\r
+ !GhcbIsRegValid (Ghcb, GhcbRdx)) {\r
+ return UnsupportedExit (Ghcb, Regs, InstructionData);\r
+ }\r
+ Regs->Rax = Ghcb->SaveArea.Rax;\r
+ Regs->Rdx = Ghcb->SaveArea.Rdx;\r
+ }\r
+\r
+ return 0;\r
+}\r
+\r