diff --git a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLibInternal.h b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLibInternal.h index 0b77cad1c0..6f7beb6ac1 100644 --- a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLibInternal.h +++ b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLibInternal.h @@ -59,4 +59,15 @@ InternalQemuFwCfgDmaBytes ( IN UINT32 Control ); +/** + Check if it is Tdx guest + + @retval TRUE It is Tdx guest + @retval FALSE It is not Tdx guest +**/ +BOOLEAN +QemuFwCfgIsTdxGuest ( + VOID + ); + #endif diff --git a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPei.c b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPei.c index f696fb7cac..b8230613dc 100644 --- a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPei.c +++ b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPei.c @@ -14,12 +14,30 @@ #include #include #include +#include #include "QemuFwCfgLibInternal.h" STATIC BOOLEAN mQemuFwCfgSupported = FALSE; STATIC BOOLEAN mQemuFwCfgDmaSupported; +/** + Check if it is Tdx guest + + @retval TRUE It is Tdx guest + @retval FALSE It is not Tdx guest +**/ +BOOLEAN +QemuFwCfgIsTdxGuest ( + VOID + ) +{ + CONFIDENTIAL_COMPUTING_WORK_AREA_HEADER *CcWorkAreaHeader; + + CcWorkAreaHeader = (CONFIDENTIAL_COMPUTING_WORK_AREA_HEADER *)FixedPcdGet32 (PcdOvmfWorkAreaBase); + return (CcWorkAreaHeader != NULL && CcWorkAreaHeader->GuestType == GUEST_TYPE_INTEL_TDX); +} + /** Returns a boolean indicating if the firmware configuration interface is available or not. @@ -81,6 +99,14 @@ QemuFwCfgInitialize ( // if (MemEncryptSevIsEnabled ()) { DEBUG ((DEBUG_INFO, "SEV: QemuFwCfg fallback to IO Port interface.\n")); + } else if (QemuFwCfgIsTdxGuest ()) { + // + // If TDX is enabled then we do not support DMA operations in PEI phase. + // This is mainly because DMA in TDX guest requires using bounce buffer + // (which need to allocate dynamic memory and allocating a PAGE size'd + // buffer can be challenge in PEI phase) + // + DEBUG ((DEBUG_INFO, "TDX: QemuFwCfg fallback to IO Port interface.\n")); } else { mQemuFwCfgDmaSupported = TRUE; DEBUG ((DEBUG_INFO, "QemuFwCfg interface (DMA) is supported.\n")); @@ -163,6 +189,12 @@ InternalQemuFwCfgDmaBytes ( // ASSERT (!MemEncryptSevIsEnabled ()); + // + // TDX does not support DMA operations in PEI stage, we should + // not have reached here. + // + ASSERT (!QemuFwCfgIsTdxGuest ()); + Access.Control = SwapBytes32 (Control); Access.Length = SwapBytes32 (Size); Access.Address = SwapBytes64 ((UINTN)Buffer); diff --git a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPeiLib.inf b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPeiLib.inf index 9f9af7d032..3910511880 100644 --- a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPeiLib.inf +++ b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPeiLib.inf @@ -43,3 +43,5 @@ MemoryAllocationLib MemEncryptSevLib +[Pcd] + gUefiOvmfPkgTokenSpaceGuid.PcdOvmfWorkAreaBase