BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4654
The PVALIDATE instruction can only be performed at VMPL0. An SVSM will
be present when running at VMPL1 or higher.
When an SVSM is present, use the SVSM_CORE_PVALIDATE call to perform
memory validation instead of issuing the PVALIDATE instruction directly.
Cc: Ard Biesheuvel <ardb+tianoc...@kernel.org>
Cc: Gerd Hoffmann <kra...@redhat.com>
Cc: Jiewen Yao <jiewen....@intel.com>
Cc: Laszlo Ersek <ler...@redhat.com>
Acked-by: Gerd Hoffmann <kra...@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com>
---
OvmfPkg/Library/AmdSvsmLib/AmdSvsmLib.c | 183 +++++++++++++++++++-
1 file changed, 182 insertions(+), 1 deletion(-)
diff --git a/OvmfPkg/Library/AmdSvsmLib/AmdSvsmLib.c
b/OvmfPkg/Library/AmdSvsmLib/AmdSvsmLib.c
index 861bf9591ae3..fb3fda70e948 100644
--- a/OvmfPkg/Library/AmdSvsmLib/AmdSvsmLib.c
+++ b/OvmfPkg/Library/AmdSvsmLib/AmdSvsmLib.c
@@ -8,6 +8,7 @@
#include <Base.h>
#include <Uefi.h>
+#include <Library/BaseMemoryLib.h>
#include <Library/AmdSvsmLib.h>
#include <Register/Amd/Msr.h>
#include <Register/Amd/Svsm.h>
@@ -43,6 +44,78 @@ SnpTerminate (
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).
@@ -109,6 +182,114 @@ AmdSvsmSnpGetCaa (
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.
@@ -193,7 +374,7 @@ AmdSvsmSnpPvalidate (
IN SNP_PAGE_STATE_CHANGE_INFO *Info
)
{
- BasePvalidate (Info);
+ AmdSvsmIsSvsmPresent () ? SvsmPvalidate (Info) : BasePvalidate (Info);
}
/**
--
2.43.2
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