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OvmfPkg/VmgExitLib: Support string IO for IOIO_PROT NAE events 

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

Add support to the #VC exception handler to handle string IO. This
requires expanding the IO instruction parsing to recognize string based
IO instructions as well as preparing an un-encrypted buffer to be used
to transfer (either to or from the guest) the string contents for the IO
operation. The SW_EXITINFO2 and SW_SCRATCH fields of the GHCB are set
appropriately for the operation. Multiple VMGEXIT invocations may be
needed to complete the string IO operation.

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Regression-tested-by: Laszlo Ersek <lersek@redhat.com>
This commit is contained in:
Tom Lendacky 2020-08-12 15:21:37 -05:00 committed by mergify[bot]
parent fb040cced3
commit 0020157a98
1 changed files with 77 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

92
OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
View File

@ -397,6 +397,26 @@ IoioExitInfo (
ExitInfo = 0;
switch (*(InstructionData->OpCodes)) {
//
// INS opcodes
//
case 0x6C:
case 0x6D:
ExitInfo |= IOIO_TYPE_INS;
ExitInfo |= IOIO_SEG_ES;
ExitInfo |= ((Regs->Rdx & 0xffff) << 16);
break;
//
// OUTS opcodes
//
case 0x6E:
case 0x6F:
ExitInfo |= IOIO_TYPE_OUTS;
ExitInfo |= IOIO_SEG_DS;
ExitInfo |= ((Regs->Rdx & 0xffff) << 16);
break;
//
// IN immediate opcodes
//
@ -445,6 +465,8 @@ IoioExitInfo (
//
// Single-byte opcodes
//
case 0x6C:
case 0x6E:
case 0xE4:
case 0xE6:
case 0xEC:
@ -506,30 +528,70 @@ IoioExit (
IN SEV_ES_INSTRUCTION_DATA *InstructionData
)
{
UINT64 ExitInfo1, Status;
UINT64 ExitInfo1, ExitInfo2, Status;
BOOLEAN IsString;
ExitInfo1 = IoioExitInfo (Regs, InstructionData);
if (ExitInfo1 == 0) {
return UnsupportedExit (Ghcb, Regs, InstructionData);
}
if ((ExitInfo1 & IOIO_TYPE_IN) != 0) {
Ghcb->SaveArea.Rax = 0;
} else {
CopyMem (&Ghcb->SaveArea.Rax, &Regs->Rax, IOIO_DATA_BYTES (ExitInfo1));
}
GhcbSetRegValid (Ghcb, GhcbRax);
IsString = ((ExitInfo1 & IOIO_TYPE_STR) != 0) ? TRUE : FALSE;
if (IsString) {
UINTN IoBytes, VmgExitBytes;
UINTN GhcbCount, OpCount;
Status = VmgExit (Ghcb, SVM_EXIT_IOIO_PROT, ExitInfo1, 0);
if (Status != 0) {
return Status;
}
Status = 0;
if ((ExitInfo1 & IOIO_TYPE_IN) != 0) {
if (!GhcbIsRegValid (Ghcb, GhcbRax)) {
return UnsupportedExit (Ghcb, Regs, InstructionData);
IoBytes = IOIO_DATA_BYTES (ExitInfo1);
GhcbCount = sizeof (Ghcb->SharedBuffer) / IoBytes;
OpCount = ((ExitInfo1 & IOIO_REP) != 0) ? Regs->Rcx : 1;
while (OpCount != 0) {
ExitInfo2 = MIN (OpCount, GhcbCount);
VmgExitBytes = ExitInfo2 * IoBytes;
if ((ExitInfo1 & IOIO_TYPE_IN) == 0) {
CopyMem (Ghcb->SharedBuffer, (VOID *) Regs->Rsi, VmgExitBytes);
Regs->Rsi += VmgExitBytes;
}
Ghcb->SaveArea.SwScratch = (UINT64) Ghcb->SharedBuffer;
Status = VmgExit (Ghcb, SVM_EXIT_IOIO_PROT, ExitInfo1, ExitInfo2);
if (Status != 0) {
return Status;
}
if ((ExitInfo1 & IOIO_TYPE_IN) != 0) {
CopyMem ((VOID *) Regs->Rdi, Ghcb->SharedBuffer, VmgExitBytes);
Regs->Rdi += VmgExitBytes;
}
if ((ExitInfo1 & IOIO_REP) != 0) {
Regs->Rcx -= ExitInfo2;
}
OpCount -= ExitInfo2;
}
} else {
if ((ExitInfo1 & IOIO_TYPE_IN) != 0) {
Ghcb->SaveArea.Rax = 0;
} else {
CopyMem (&Ghcb->SaveArea.Rax, &Regs->Rax, IOIO_DATA_BYTES (ExitInfo1));
}
GhcbSetRegValid (Ghcb, GhcbRax);
Status = VmgExit (Ghcb, SVM_EXIT_IOIO_PROT, ExitInfo1, 0);
if (Status != 0) {
return Status;
}
if ((ExitInfo1 & IOIO_TYPE_IN) != 0) {
if (!GhcbIsRegValid (Ghcb, GhcbRax)) {
return UnsupportedExit (Ghcb, Regs, InstructionData);
}
CopyMem (&Regs->Rax, &Ghcb->SaveArea.Rax, IOIO_DATA_BYTES (ExitInfo1));
}
CopyMem (&Regs->Rax, &Ghcb->SaveArea.Rax, IOIO_DATA_BYTES (ExitInfo1));
}
return 0;