OvmfPkg/IoMmuDxe: Add SEV support for reserved shared memory

Add support to use the reserved shared memory within the IoMmu library.
This improves boot times for all SEV guests, with SEV-SNP benefiting the
most as it avoids the page state change call to the hypervisor.

Cc: Erdem Aktas <erdemaktas@google.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Min Xu <min.m.xu@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Jiewen Yao <Jiewen.yao@intel.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>

2 files changed, 83 insertions, 53 deletions

diff --git a/OvmfPkg/IoMmuDxe/CcIoMmu.c b/OvmfPkg/IoMmuDxe/CcIoMmu.c
index 1479af4..7c2843c 100644
--- a/OvmfPkg/IoMmuDxe/CcIoMmu.c
+++ b/OvmfPkg/IoMmuDxe/CcIoMmu.c
@@ -223,30 +223,32 @@ IoMmuMap (
       goto FreeMapInfo;

   }

 

-  if (CC_GUEST_IS_SEV (PcdGet64 (PcdConfidentialComputingGuestAttr))) {

+  if (MapInfo->ReservedMemBitmap == 0) {

     //

-    // Clear the memory encryption mask on the plaintext buffer.

-    //

-    Status = MemEncryptSevClearPageEncMask (

-               0,

-               MapInfo->PlainTextAddress,

-               MapInfo->NumberOfPages

-               );

-  } else if (CC_GUEST_IS_TDX (PcdGet64 (PcdConfidentialComputingGuestAttr))) {

-    //

-    // Set the memory shared bit.

     // If MapInfo->ReservedMemBitmap is 0, it means the bounce buffer is not allocated

     // from the pre-allocated shared memory, so it must be converted to shared memory here.

     //

-    if (MapInfo->ReservedMemBitmap == 0) {

+    if (CC_GUEST_IS_SEV (PcdGet64 (PcdConfidentialComputingGuestAttr))) {

+      //

+      // Clear the memory encryption mask on the plaintext buffer.

+      //

+      Status = MemEncryptSevClearPageEncMask (

+                 0,

+                 MapInfo->PlainTextAddress,

+                 MapInfo->NumberOfPages

+                 );

+    } else if (CC_GUEST_IS_TDX (PcdGet64 (PcdConfidentialComputingGuestAttr))) {

+      //

+      // Set the memory shared bit.

+      //

       Status = MemEncryptTdxSetPageSharedBit (

                  0,

                  MapInfo->PlainTextAddress,

                  MapInfo->NumberOfPages

                  );

+    } else {

+      ASSERT (FALSE);

     }

-  } else {

-    ASSERT (FALSE);

   }

 

   ASSERT_EFI_ERROR (Status);

@@ -396,30 +398,30 @@ IoMmuUnmapWorker (
       break;

   }

 

-  if (CC_GUEST_IS_SEV (PcdGet64 (PcdConfidentialComputingGuestAttr))) {

-    //

-    // Restore the memory encryption mask on the area we used to hold the

-    // plaintext.

-    //

-    Status = MemEncryptSevSetPageEncMask (

-               0,

-               MapInfo->PlainTextAddress,

-               MapInfo->NumberOfPages

-               );

-  } else if (CC_GUEST_IS_TDX (PcdGet64 (PcdConfidentialComputingGuestAttr))) {

-    //

-    // Restore the memory shared bit mask on the area we used to hold the

-    // plaintext.

-    //

-    if (MapInfo->ReservedMemBitmap == 0) {

+  if (MapInfo->ReservedMemBitmap == 0) {

+    if (CC_GUEST_IS_SEV (PcdGet64 (PcdConfidentialComputingGuestAttr))) {

+      //

+      // Restore the memory encryption mask on the area we used to hold the

+      // plaintext.

+      //

+      Status = MemEncryptSevSetPageEncMask (

+                 0,

+                 MapInfo->PlainTextAddress,

+                 MapInfo->NumberOfPages

+                 );

+    } else if (CC_GUEST_IS_TDX (PcdGet64 (PcdConfidentialComputingGuestAttr))) {

+      //

+      // Restore the memory shared bit mask on the area we used to hold the

+      // plaintext.

+      //

       Status = MemEncryptTdxClearPageSharedBit (

                  0,

                  MapInfo->PlainTextAddress,

                  MapInfo->NumberOfPages

                  );

+    } else {

+      ASSERT (FALSE);

     }

-  } else {

-    ASSERT (FALSE);

   }

 

   ASSERT_EFI_ERROR (Status);

@@ -924,16 +926,14 @@ InstallIoMmuProtocol (
   }

 

   //

-  // Currently only Tdx guest support Reserved shared memory for DMA operation.

+  // For CC guests, use reserved shared memory for DMA operation.

   //

-  if (CC_GUEST_IS_TDX (PcdGet64 (PcdConfidentialComputingGuestAttr))) {

-    mReservedSharedMemSupported = TRUE;

-    Status                      = IoMmuInitReservedSharedMem ();

-    if (EFI_ERROR (Status)) {

-      mReservedSharedMemSupported = FALSE;

-    } else {

-      DEBUG ((DEBUG_INFO, "%a: Feature of reserved memory for DMA is supported.\n", __FUNCTION__));

-    }

+  mReservedSharedMemSupported = TRUE;

+  Status                      = IoMmuInitReservedSharedMem ();

+  if (EFI_ERROR (Status)) {

+    mReservedSharedMemSupported = FALSE;

+  } else {

+    DEBUG ((DEBUG_INFO, "%a: Feature of reserved memory for DMA is supported.\n", __FUNCTION__));

   }

 

   return EFI_SUCCESS;

diff --git a/OvmfPkg/IoMmuDxe/IoMmuBuffer.c b/OvmfPkg/IoMmuDxe/IoMmuBuffer.c
index 2675223..83c7c59 100644
--- a/OvmfPkg/IoMmuDxe/IoMmuBuffer.c
+++ b/OvmfPkg/IoMmuDxe/IoMmuBuffer.c
@@ -9,7 +9,9 @@
 #include <Library/BaseMemoryLib.h>

 #include <Library/DebugLib.h>

 #include <Library/MemoryAllocationLib.h>

+#include <Library/MemEncryptSevLib.h>

 #include <Library/MemEncryptTdxLib.h>

+#include <Library/PcdLib.h>

 #include <Library/UefiBootServicesTableLib.h>

 #include "IoMmuInternal.h"

 

@@ -139,6 +141,7 @@ IoMmuInitReservedSharedMem (
   UINTN                     TotalPages;

   IOMMU_RESERVED_MEM_RANGE  *MemRange;

   EFI_PHYSICAL_ADDRESS      PhysicalAddress;

+  UINT64                    SharedAddress;

 

   if (!mReservedSharedMemSupported) {

     return EFI_UNSUPPORTED;

@@ -163,12 +166,25 @@ IoMmuInitReservedSharedMem (
     MemRange->StartAddressOfMemRange = PhysicalAddress;

 

     for (Index2 = 0; Index2 < MemRange->Slots; Index2++) {

-      Status = MemEncryptTdxSetPageSharedBit (

-                 0,

-                 (UINT64)(UINTN)(MemRange->StartAddressOfMemRange + Index2 * SIZE_OF_MEM_RANGE (MemRange) + MemRange->HeaderSize),

-                 EFI_SIZE_TO_PAGES (MemRange->DataSize)

-                 );

-      ASSERT (!EFI_ERROR (Status));

+      SharedAddress = (UINT64)(UINTN)(MemRange->StartAddressOfMemRange + Index2 * SIZE_OF_MEM_RANGE (MemRange) + MemRange->HeaderSize);

+

+      if (CC_GUEST_IS_SEV (PcdGet64 (PcdConfidentialComputingGuestAttr))) {

+        Status = MemEncryptSevClearPageEncMask (

+                   0,

+                   SharedAddress,

+                   EFI_SIZE_TO_PAGES (MemRange->DataSize)

+                   );

+        ASSERT (!EFI_ERROR (Status));

+      } else if (CC_GUEST_IS_TDX (PcdGet64 (PcdConfidentialComputingGuestAttr))) {

+        Status = MemEncryptTdxSetPageSharedBit (

+                   0,

+                   SharedAddress,

+                   EFI_SIZE_TO_PAGES (MemRange->DataSize)

+                   );

+        ASSERT (!EFI_ERROR (Status));

+      } else {

+        ASSERT (FALSE);

+      }

     }

 

     PhysicalAddress += (MemRange->Slots * SIZE_OF_MEM_RANGE (MemRange));

@@ -190,6 +206,7 @@ IoMmuReleaseReservedSharedMem (
   EFI_STATUS                Status;

   UINT32                    Index1, Index2;

   IOMMU_RESERVED_MEM_RANGE  *MemRange;

+  UINT64                    SharedAddress;

 

   if (!mReservedSharedMemSupported) {

     return EFI_SUCCESS;

@@ -198,12 +215,25 @@ IoMmuReleaseReservedSharedMem (
   for (Index1 = 0; Index1 < ARRAY_SIZE (mReservedMemRanges); Index1++) {

     MemRange = &mReservedMemRanges[Index1];

     for (Index2 = 0; Index2 < MemRange->Slots; Index2++) {

-      Status = MemEncryptTdxClearPageSharedBit (

-                 0,

-                 (UINT64)(UINTN)(MemRange->StartAddressOfMemRange + Index2 * SIZE_OF_MEM_RANGE (MemRange) + MemRange->HeaderSize),

-                 EFI_SIZE_TO_PAGES (MemRange->DataSize)

-                 );

-      ASSERT (!EFI_ERROR (Status));

+      SharedAddress = (UINT64)(UINTN)(MemRange->StartAddressOfMemRange + Index2 * SIZE_OF_MEM_RANGE (MemRange) + MemRange->HeaderSize);

+

+      if (CC_GUEST_IS_SEV (PcdGet64 (PcdConfidentialComputingGuestAttr))) {

+        Status = MemEncryptSevSetPageEncMask (

+                   0,

+                   SharedAddress,

+                   EFI_SIZE_TO_PAGES (MemRange->DataSize)

+                   );

+        ASSERT (!EFI_ERROR (Status));

+      } else if (CC_GUEST_IS_TDX (PcdGet64 (PcdConfidentialComputingGuestAttr))) {

+        Status = MemEncryptTdxClearPageSharedBit (

+                   0,

+                   SharedAddress,

+                   EFI_SIZE_TO_PAGES (MemRange->DataSize)

+                   );

+        ASSERT (!EFI_ERROR (Status));

+      } else {

+        ASSERT (FALSE);

+      }

     }

   }