Re: [edk2-devel] [PATCH v8 22/46] OvmfPkg/VmgExitLib: Add support for VMMCALL NAE events

["Lendacky, Thomas" <thomas.lendacky@amd.com>]

On 5/22/20 9:50 AM, Laszlo Ersek via groups.io wrote:
> On 05/22/20 16:48, Laszlo Ersek wrote:
>> On 05/19/20 23:50, Lendacky, Thomas wrote:
>>> BZ: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugzilla.tianocore.org%2Fshow_bug.cgi%3Fid%3D2198&data=02%7C01%7Cthomas.lendacky%40amd.com%7Cba73e0d6ccb9488ab10608d7fe5f7c8f%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637257558381229776&sdata=kwjA9Hgo1KKgY%2FarqEiQFDg5QVpx60Kfoh1AWqSuock%3D&reserved=0
>>>
>>> Under SEV-ES, a VMMCALL intercept generates a #VC exception. VMGEXIT must
>>> be used to allow the hypervisor to handle this intercept.
>>>
>>> Cc: Jordan Justen <jordan.l.justen@intel.com>
>>> Cc: Laszlo Ersek <lersek@redhat.com>
>>> Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
>>> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
>>> ---
>>>   .../Library/VmgExitLib/X64/VmgExitVcHandler.c | 48 +++++++++++++++++++
>>>   1 file changed, 48 insertions(+)
>>>
>>> diff --git a/OvmfPkg/Library/VmgExitLib/X64/VmgExitVcHandler.c b/OvmfPkg/Library/VmgExitLib/X64/VmgExitVcHandler.c
>>> index 0b7f24fd962c..bf1555234d69 100644
>>> --- a/OvmfPkg/Library/VmgExitLib/X64/VmgExitVcHandler.c
>>> +++ b/OvmfPkg/Library/VmgExitLib/X64/VmgExitVcHandler.c
>>> @@ -875,6 +875,50 @@ WbinvdExit (
>>>     return 0;
>>>   }
>>>   
>>> +/**
>>> +  Handle a VMMCALL event.
>>> +
>>> +  Use the VMGEXIT instruction to handle either a VMMCALL event.
> 
> (2) pls drop the word "either".

I have this in a couple of places, so I'll take care of all of them.

Thanks!
TOm

> 
> Thanks
> Laszlo
> 
>>> +
>>> +  @param[in, out] Ghcb             Pointer to the Guest-Hypervisor Communication
>>> +                                   Block
>>> +  @param[in, out] Regs             x64 processor context
>>> +  @param[in]      InstructionData  Instruction parsing context
>>> +
>>> +  @retval 0                        Event handled successfully
>>> +  @retval Others                   New exception value to propagate
>>> +
>>> +**/
>>> +STATIC
>>> +UINT64
>>> +VmmCallExit (
>>> +  IN OUT GHCB                     *Ghcb,
>>> +  IN OUT EFI_SYSTEM_CONTEXT_X64   *Regs,
>>> +  IN     SEV_ES_INSTRUCTION_DATA  *InstructionData
>>> +  )
>>> +{
>>> +  UINT64  Status;
>>> +
>>> +  DecodeModRm (Regs, InstructionData);
>>> +
>>> +  Ghcb->SaveArea.Rax = Regs->Rax;
>>> +  GhcbSetRegValid (Ghcb, GhcbRax);
>>> +  Ghcb->SaveArea.Cpl = (UINT8) (Regs->Cs & 0x3);
>>> +  GhcbSetRegValid (Ghcb, GhcbCpl);
>>> +
>>> +  Status = VmgExit (Ghcb, SVM_EXIT_VMMCALL, 0, 0);
>>> +  if (Status) {
>>
>> (1) Please write (Status > 0) or (Status != 0).
>>
>> Acked-by: Laszlo Ersek <lersek@redhat.com>
>>
>> Thanks
>> Laszlo
>>
>>> +    return Status;
>>> +  }
>>> +
>>> +  if (!GhcbIsRegValid (Ghcb, GhcbRax)) {
>>> +    return UnsupportedExit (Ghcb, Regs, InstructionData);
>>> +  }
>>> +  Regs->Rax = Ghcb->SaveArea.Rax;
>>> +
>>> +  return 0;
>>> +}
>>> +
>>>   /**
>>>     Handle an MSR event.
>>>   
>>> @@ -1395,6 +1439,10 @@ VmgExitHandleVc (
>>>       NaeExit = MsrExit;
>>>       break;
>>>   
>>> +  case SVM_EXIT_VMMCALL:
>>> +    NaeExit = VmmCallExit;
>>> +    break;
>>> +
>>>     case SVM_EXIT_WBINVD:
>>>       NaeExit = WbinvdExit;
>>>       break;
>>>
>>
> 
> 
> 
>