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audk/OvmfPkg/Library/AmdSvsmLib/AmdSvsmLib.c

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/** @file
SVSM Support Library.
Copyright (C) 2024, Advanced Micro Devices, Inc. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include <Base.h>
#include <Uefi.h>
#include <Library/BaseMemoryLib.h>
#include <Library/AmdSvsmLib.h>
#include <Register/Amd/Msr.h>
#include <Register/Amd/Svsm.h>
#define PAGES_PER_2MB_ENTRY 512
/**
Issue a GHCB termination request for termination.
Request termination using the GHCB MSR protocol.
**/
STATIC
VOID
SnpTerminate (
VOID
)
{
MSR_SEV_ES_GHCB_REGISTER Msr;
//
// Use the GHCB MSR Protocol to request termination by the hypervisor
//
Msr.Uint64 = 0;
Msr.GhcbTerminate.Function = GHCB_INFO_TERMINATE_REQUEST;
Msr.GhcbTerminate.ReasonCodeSet = GHCB_TERMINATE_GHCB;
Msr.GhcbTerminate.ReasonCode = GHCB_TERMINATE_GHCB_GENERAL;
AsmWriteMsr64 (MSR_SEV_ES_GHCB, Msr.Uint64);
AsmVmgExit ();
ASSERT (FALSE);
CpuDeadLoop ();
}
/**
Issue an SVSM request.
Invokes the SVSM to process a request on behalf of the guest.
@param[in,out] SvsmCallData Pointer to the SVSM call data
@return Contents of RAX upon return from VMGEXIT
**/
STATIC
UINTN
SvsmMsrProtocol (
IN OUT SVSM_CALL_DATA *SvsmCallData
)
{
MSR_SEV_ES_GHCB_REGISTER Msr;
UINT64 CurrentMsr;
UINT8 Pending;
BOOLEAN InterruptState;
UINTN Ret;
do {
//
// Be sure that an interrupt can't cause a #VC while the GHCB MSR protocol
// is being used (#VC handler will ASSERT if lower 12-bits are not zero).
//
InterruptState = GetInterruptState ();
if (InterruptState) {
DisableInterrupts ();
}
Pending = 0;
SvsmCallData->CallPending = &Pending;
CurrentMsr = AsmReadMsr64 (MSR_SEV_ES_GHCB);
Msr.Uint64 = 0;
Msr.SnpVmplRequest.Function = GHCB_INFO_SNP_VMPL_REQUEST;
Msr.SnpVmplRequest.Vmpl = 0;
AsmWriteMsr64 (MSR_SEV_ES_GHCB, Msr.Uint64);
//
// Guest memory is used for the guest-SVSM communication, so fence the
// invocation of the VMGEXIT instruction to ensure VMSA accesses are
// synchronized properly.
//
MemoryFence ();
Ret = AsmVmgExitSvsm (SvsmCallData);
MemoryFence ();
Msr.Uint64 = AsmReadMsr64 (MSR_SEV_ES_GHCB);
AsmWriteMsr64 (MSR_SEV_ES_GHCB, CurrentMsr);
if (InterruptState) {
EnableInterrupts ();
}
if (Pending != 0) {
SnpTerminate ();
}
if ((Msr.SnpVmplResponse.Function != GHCB_INFO_SNP_VMPL_RESPONSE) ||
(Msr.SnpVmplResponse.ErrorCode != 0))
{
SnpTerminate ();
}
} while (Ret == SVSM_ERR_INCOMPLETE || Ret == SVSM_ERR_BUSY);
return Ret;
}
/**
Report the presence of an Secure Virtual Services Module (SVSM).
Determines the presence of an SVSM.
@retval TRUE An SVSM is present
@retval FALSE An SVSM is not present
**/
BOOLEAN
EFIAPI
AmdSvsmIsSvsmPresent (
VOID
)
{
SVSM_INFORMATION *SvsmInfo;
SvsmInfo = (SVSM_INFORMATION *)(UINTN)PcdGet32 (PcdOvmfSnpSecretsBase);
return (SvsmInfo != NULL && SvsmInfo->SvsmSize != 0);
}
/**
Report the VMPL level at which the SEV-SNP guest is running.
Determines the VMPL level at which the guest is running. If an SVSM is
not present, then it must be VMPL0, otherwise return what is reported
by the SVSM.
@return The VMPL level
**/
UINT8
EFIAPI
AmdSvsmSnpGetVmpl (
VOID
)
{
SVSM_INFORMATION *SvsmInfo;
SvsmInfo = (SVSM_INFORMATION *)(UINTN)PcdGet32 (PcdOvmfSnpSecretsBase);
return AmdSvsmIsSvsmPresent () ? SvsmInfo->SvsmGuestVmpl : 0;
}
/**
Report the Calling Area address (CAA) for the BSP of the SEV-SNP guest.
If an SVSM is present, the CAA for the BSP is returned.
@return The CAA
**/
UINT64
EFIAPI
AmdSvsmSnpGetCaa (
VOID
)
{
SVSM_INFORMATION *SvsmInfo;
SvsmInfo = (SVSM_INFORMATION *)(UINTN)PcdGet32 (PcdOvmfSnpSecretsBase);
return AmdSvsmIsSvsmPresent () ? SvsmInfo->SvsmCaa : 0;
}
/**
Issue an SVSM request to perform the PVALIDATE instruction.
Invokes the SVSM to process the PVALIDATE instruction on behalf of the
guest to validate or invalidate the memory range specified.
@param[in] Info Pointer to a page state change structure
**/
STATIC
VOID
SvsmPvalidate (
IN SNP_PAGE_STATE_CHANGE_INFO *Info
)
{
SVSM_CALL_DATA SvsmCallData;
SVSM_CAA *Caa;
SVSM_PVALIDATE_REQUEST *Request;
SVSM_FUNCTION Function;
BOOLEAN Validate;
UINTN Entry;
UINTN EntryLimit;
UINTN Index;
UINTN EndIndex;
UINT64 Gfn;
UINT64 GfnEnd;
UINTN Ret;
Caa = (SVSM_CAA *)AmdSvsmSnpGetCaa ();
ZeroMem (Caa->SvsmBuffer, sizeof (Caa->SvsmBuffer));
Function.Id.Protocol = 0;
Function.Id.CallId = 1;
Request = (SVSM_PVALIDATE_REQUEST *)Caa->SvsmBuffer;
EntryLimit = ((sizeof (Caa->SvsmBuffer) - sizeof (*Request)) /
sizeof (Request->Entry[0])) - 1;
SvsmCallData.Caa = Caa;
SvsmCallData.RaxIn = Function.Uint64;
SvsmCallData.RcxIn = (UINT64)(UINTN)Request;
Entry = 0;
Index = Info->Header.CurrentEntry;
EndIndex = Info->Header.EndEntry;
while (Index <= EndIndex) {
Validate = Info->Entry[Index].Operation == SNP_PAGE_STATE_PRIVATE;
Request->Header.Entries++;
Request->Entry[Entry].Bits.PageSize = Info->Entry[Index].PageSize;
Request->Entry[Entry].Bits.Action = (Validate == TRUE) ? 1 : 0;
Request->Entry[Entry].Bits.IgnoreCf = 0;
Request->Entry[Entry].Bits.Address = Info->Entry[Index].GuestFrameNumber;
Entry++;
if ((Entry > EntryLimit) || (Index == EndIndex)) {
Ret = SvsmMsrProtocol (&SvsmCallData);
if ((Ret == SVSM_ERR_PVALIDATE_FAIL_SIZE_MISMATCH) &&
(Request->Entry[Request->Header.Next].Bits.PageSize != 0))
{
// Calculate the Index of the entry after the entry that failed
// before clearing the buffer so that processing can continue
// from that point
Index = Index - (Entry - Request->Header.Next) + 2;
// Obtain the failing GFN before clearing the buffer
Gfn = Request->Entry[Request->Header.Next].Bits.Address;
// Clear the buffer in prep for creating all new entries
ZeroMem (Caa->SvsmBuffer, sizeof (Caa->SvsmBuffer));
Entry = 0;
GfnEnd = Gfn + PAGES_PER_2MB_ENTRY - 1;
for ( ; Gfn <= GfnEnd; Gfn++) {
Request->Header.Entries++;
Request->Entry[Entry].Bits.PageSize = 0;
Request->Entry[Entry].Bits.Action = (Validate == TRUE) ? 1 : 0;
Request->Entry[Entry].Bits.IgnoreCf = 0;
Request->Entry[Entry].Bits.Address = Gfn;
Entry++;
if ((Entry > EntryLimit) || (Gfn == GfnEnd)) {
Ret = SvsmMsrProtocol (&SvsmCallData);
if (Ret != 0) {
SnpTerminate ();
}
ZeroMem (Caa->SvsmBuffer, sizeof (Caa->SvsmBuffer));
Entry = 0;
}
}
continue;
}
if (Ret != 0) {
SnpTerminate ();
}
ZeroMem (Caa->SvsmBuffer, sizeof (Caa->SvsmBuffer));
Entry = 0;
}
Index++;
}
}
/**
Perform a native PVALIDATE operation for the page ranges specified.
Validate or rescind the validation of the specified pages.
@param[in] Info Pointer to a page state change structure
**/
STATIC
VOID
BasePvalidate (
IN SNP_PAGE_STATE_CHANGE_INFO *Info
)
{
UINTN RmpPageSize;
UINTN StartIndex;
UINTN EndIndex;
UINTN Index;
UINTN Ret;
EFI_PHYSICAL_ADDRESS Address;
BOOLEAN Validate;
StartIndex = Info->Header.CurrentEntry;
EndIndex = Info->Header.EndEntry;
for ( ; StartIndex <= EndIndex; StartIndex++) {
//
// Get the address and the page size from the Info.
//
Address = ((EFI_PHYSICAL_ADDRESS)Info->Entry[StartIndex].GuestFrameNumber) << EFI_PAGE_SHIFT;
RmpPageSize = Info->Entry[StartIndex].PageSize;
Validate = Info->Entry[StartIndex].Operation == SNP_PAGE_STATE_PRIVATE;
Ret = AsmPvalidate (RmpPageSize, Validate, Address);
//
// If we fail to validate due to size mismatch then try with the
// smaller page size. This senario will occur if the backing page in
// the RMP entry is 4K and we are validating it as a 2MB.
//
if ((Ret == PVALIDATE_RET_SIZE_MISMATCH) && (RmpPageSize == PvalidatePageSize2MB)) {
for (Index = 0; Index < PAGES_PER_2MB_ENTRY; Index++) {
Ret = AsmPvalidate (PvalidatePageSize4K, Validate, Address);
if (Ret) {
break;
}
Address = Address + EFI_PAGE_SIZE;
}
}
//
// If validation failed then do not continue.
//
if (Ret) {
DEBUG ((
DEBUG_ERROR,
"%a:%a: Failed to %a address 0x%Lx Error code %d\n",
gEfiCallerBaseName,
__func__,
Validate ? "Validate" : "Invalidate",
Address,
Ret
));
SnpTerminate ();
}
}
}
/**
Perform a PVALIDATE operation for the page ranges specified.
Validate or rescind the validation of the specified pages.
@param[in] Info Pointer to a page state change structure
**/
VOID
EFIAPI
AmdSvsmSnpPvalidate (
IN SNP_PAGE_STATE_CHANGE_INFO *Info
)
{
AmdSvsmIsSvsmPresent () ? SvsmPvalidate (Info) : BasePvalidate (Info);
}
/**
Perform an RMPADJUST operation to alter the VMSA setting of a page.
Add or remove the VMSA attribute for a page.
@param[in] Vmsa Pointer to an SEV-ES save area page
@param[in] ApicId APIC ID associated with the VMSA
@param[in] SetVmsa Boolean indicator as to whether to set or
or clear the VMSA setting for the page
@retval EFI_SUCCESS RMPADJUST operation successful
@retval EFI_UNSUPPORTED Operation is not supported
@retval EFI_INVALID_PARAMETER RMPADJUST operation failed, an invalid
parameter was supplied
**/
STATIC
EFI_STATUS
SvsmVmsaRmpAdjust (
IN SEV_ES_SAVE_AREA *Vmsa,
IN UINT32 ApicId,
IN BOOLEAN SetVmsa
)
{
SVSM_CALL_DATA SvsmCallData;
SVSM_FUNCTION Function;
UINTN Ret;
SvsmCallData.Caa = (SVSM_CAA *)AmdSvsmSnpGetCaa ();
Function.Id.Protocol = 0;
if (SetVmsa) {
Function.Id.CallId = 2;
SvsmCallData.RaxIn = Function.Uint64;
SvsmCallData.RcxIn = (UINT64)(UINTN)Vmsa;
SvsmCallData.RdxIn = (UINT64)(UINTN)Vmsa + SIZE_4KB;
SvsmCallData.R8In = ApicId;
} else {
Function.Id.CallId = 3;
SvsmCallData.RaxIn = Function.Uint64;
SvsmCallData.RcxIn = (UINT64)(UINTN)Vmsa;
}
Ret = SvsmMsrProtocol (&SvsmCallData);
return (Ret == 0) ? EFI_SUCCESS : EFI_INVALID_PARAMETER;
}
/**
Perform a native RMPADJUST operation to alter the VMSA setting of a page.
Add or remove the VMSA attribute for a page.
@param[in] Vmsa Pointer to an SEV-ES save area page
@param[in] SetVmsa Boolean indicator as to whether to set or
or clear the VMSA setting for the page
@retval EFI_SUCCESS RMPADJUST operation successful
@retval EFI_INVALID_PARAMETER RMPADJUST operation failed, an invalid
parameter was supplied
**/
STATIC
EFI_STATUS
BaseVmsaRmpAdjust (
IN SEV_ES_SAVE_AREA *Vmsa,
IN BOOLEAN SetVmsa
)
{
UINT64 Rdx;
UINT32 Ret;
//
// The RMPADJUST instruction is used to set or clear the VMSA bit for a
// page. The VMSA change is only made when running at VMPL0 and is ignored
// otherwise. If too low a target VMPL is specified, the instruction can
// succeed without changing the VMSA bit when not running at VMPL0. Using a
// target VMPL level of 1, RMPADJUST will return a FAIL_PERMISSION error if
// not running at VMPL0, thus ensuring that the VMSA bit is set appropriately
// when no error is returned.
//
Rdx = 1;
if (SetVmsa) {
Rdx |= RMPADJUST_VMSA_PAGE_BIT;
}
Ret = AsmRmpAdjust ((UINT64)(UINTN)Vmsa, 0, Rdx);
return (Ret == 0) ? EFI_SUCCESS : EFI_INVALID_PARAMETER;
}
/**
Perform an RMPADJUST operation to alter the VMSA setting of a page.
Add or remove the VMSA attribute for a page.
@param[in] Vmsa Pointer to an SEV-ES save area page
@param[in] ApicId APIC ID associated with the VMSA
@param[in] SetVmsa Boolean indicator as to whether to set or
or clear the VMSA setting for the page
@retval EFI_SUCCESS RMPADJUST operation successful
@retval EFI_UNSUPPORTED Operation is not supported
@retval EFI_INVALID_PARAMETER RMPADJUST operation failed, an invalid
parameter was supplied
**/
EFI_STATUS
EFIAPI
AmdSvsmSnpVmsaRmpAdjust (
IN SEV_ES_SAVE_AREA *Vmsa,
IN UINT32 ApicId,
IN BOOLEAN SetVmsa
)
{
return AmdSvsmIsSvsmPresent () ? SvsmVmsaRmpAdjust (Vmsa, ApicId, SetVmsa)
: BaseVmsaRmpAdjust (Vmsa, SetVmsa);
}
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