[edk2-devel] [PATCH v2 2/3] OvmfPkg/BaseMemEncryptLib: Support to issue unencrypted hypercall
Ashish Kalra
ashish.kalra at amd.com
Thu Dec 3 22:27:05 UTC 2020
From: Brijesh Singh <brijesh.singh at amd.com>
By default all the SEV guest memory regions are considered encrypted,
if a guest changes the encryption attribute of the page (e.g mark a
page as decrypted) then notify hypervisor. Hypervisor will need to
track the unencrypted pages. The information will be used during
guest live migration, guest page migration and guest debugging.
Invoke hypercall via the new hypercall library.
This hypercall is used to notify hypervisor when a page is marked as
'decrypted' (i.e C-bit removed).
Cc: Jordan Justen <jordan.l.justen at intel.com>
Cc: Laszlo Ersek <lersek at redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel at arm.com>
Signed-off-by: Brijesh Singh <brijesh.singh at amd.com>
Signed-off-by: Ashish Kalra <ashish.kalra at amd.com>
---
OvmfPkg/Library/BaseMemEncryptSevLib/BaseMemEncryptSevLib.inf | 1 +
OvmfPkg/Library/BaseMemEncryptSevLib/X64/VirtualMemory.c | 18 ++++++++++++++++++
2 files changed, 19 insertions(+)
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/BaseMemEncryptSevLib.inf b/OvmfPkg/Library/BaseMemEncryptSevLib/BaseMemEncryptSevLib.inf
index 7c44d09528..95ee707918 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/BaseMemEncryptSevLib.inf
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/BaseMemEncryptSevLib.inf
@@ -46,6 +46,7 @@
DebugLib
MemoryAllocationLib
PcdLib
+ MemEncryptHypercallLib
[FeaturePcd]
gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/VirtualMemory.c b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/VirtualMemory.c
index 5e110c84ff..1e670b6200 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/VirtualMemory.c
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/VirtualMemory.c
@@ -14,6 +14,7 @@
#include <Library/CpuLib.h>
#include <Register/Amd/Cpuid.h>
#include <Register/Cpuid.h>
+#include <Library/MemEncryptHypercallLib.h>
#include "VirtualMemory.h"
@@ -589,6 +590,9 @@ SetMemoryEncDec (
UINT64 AddressEncMask;
BOOLEAN IsWpEnabled;
RETURN_STATUS Status;
+ UINTN Size;
+ BOOLEAN CBitChanged;
+ PHYSICAL_ADDRESS OrigPhysicalAddress;
//
// Set PageMapLevel4Entry to suppress incorrect compiler/analyzer warnings.
@@ -640,6 +644,10 @@ SetMemoryEncDec (
Status = EFI_SUCCESS;
+ Size = Length;
+ CBitChanged = FALSE;
+ OrigPhysicalAddress = PhysicalAddress;
+
while (Length)
{
//
@@ -699,6 +707,7 @@ SetMemoryEncDec (
));
PhysicalAddress += BIT30;
Length -= BIT30;
+ CBitChanged = TRUE;
} else {
//
// We must split the page
@@ -753,6 +762,7 @@ SetMemoryEncDec (
SetOrClearCBit (&PageDirectory2MEntry->Uint64, Mode);
PhysicalAddress += BIT21;
Length -= BIT21;
+ CBitChanged = TRUE;
} else {
//
// We must split up this page into 4K pages
@@ -795,6 +805,7 @@ SetMemoryEncDec (
SetOrClearCBit (&PageTableEntry->Uint64, Mode);
PhysicalAddress += EFI_PAGE_SIZE;
Length -= EFI_PAGE_SIZE;
+ CBitChanged = TRUE;
}
}
}
@@ -812,6 +823,13 @@ SetMemoryEncDec (
//
CpuFlushTlb();
+ //
+ // Notify Hypervisor on C-bit status
+ //
+ if (CBitChanged) {
+ SetMemoryEncDecHypercall3 (OrigPhysicalAddress, EFI_SIZE_TO_PAGES(Size), !Mode);
+ }
+
Done:
//
// Restore page table write protection, if any.
--
2.17.1
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