diff options
Diffstat (limited to 'OvmfPkg/ResetVector')
| -rw-r--r-- | OvmfPkg/ResetVector/Ia32/PageTables64.asm | 76 | ||||
| -rw-r--r-- | OvmfPkg/ResetVector/ResetVector.inf | 5 | ||||
| -rw-r--r-- | OvmfPkg/ResetVector/ResetVector.nasmb | 17 |
3 files changed, 98 insertions, 0 deletions
diff --git a/OvmfPkg/ResetVector/Ia32/PageTables64.asm b/OvmfPkg/ResetVector/Ia32/PageTables64.asm index abad009f20..9f86ddf6f0 100644 --- a/OvmfPkg/ResetVector/Ia32/PageTables64.asm +++ b/OvmfPkg/ResetVector/Ia32/PageTables64.asm @@ -21,6 +21,11 @@ BITS 32 %define PAGE_2M_MBO 0x080
%define PAGE_2M_PAT 0x01000
+%define PAGE_4K_PDE_ATTR (PAGE_ACCESSED + \
+ PAGE_DIRTY + \
+ PAGE_READ_WRITE + \
+ PAGE_PRESENT)
+
%define PAGE_2M_PDE_ATTR (PAGE_2M_MBO + \
PAGE_ACCESSED + \
PAGE_DIRTY + \
@@ -75,6 +80,37 @@ NoSev: SevExit:
OneTimeCallRet CheckSevFeature
+; Check if Secure Encrypted Virtualization - Encrypted State (SEV-ES) feature
+; is enabled.
+;
+; Modified: EAX, EBX, ECX
+;
+; If SEV-ES is enabled then EAX will be non-zero.
+; If SEV-ES is disabled then EAX will be zero.
+;
+CheckSevEsFeature:
+ xor eax, eax
+
+ ; SEV-ES can't be enabled if SEV isn't, so first check the encryption
+ ; mask.
+ test edx, edx
+ jz NoSevEs
+
+ ; Save current value of encryption mask
+ mov ebx, edx
+
+ ; Check if SEV-ES is enabled
+ ; MSR_0xC0010131 - Bit 1 (SEV-ES enabled)
+ mov ecx, 0xc0010131
+ rdmsr
+ and eax, 2
+
+ ; Restore encryption mask
+ mov edx, ebx
+
+NoSevEs:
+ OneTimeCallRet CheckSevEsFeature
+
;
; Modified: EAX, EBX, ECX, EDX
;
@@ -139,6 +175,46 @@ pageTableEntriesLoop: mov [(ecx * 8 + PT_ADDR (0x2000 - 8)) + 4], edx
loop pageTableEntriesLoop
+ OneTimeCall CheckSevEsFeature
+ test eax, eax
+ jz SetCr3
+
+ ;
+ ; The initial GHCB will live at GHCB_BASE and needs to be un-encrypted.
+ ; This requires the 2MB page for this range be broken down into 512 4KB
+ ; pages. All will be marked encrypted, except for the GHCB.
+ ;
+ mov ecx, (GHCB_BASE >> 21)
+ mov eax, GHCB_PT_ADDR + PAGE_PDP_ATTR
+ mov [ecx * 8 + PT_ADDR (0x2000)], eax
+
+ ;
+ ; Page Table Entries (512 * 4KB entries => 2MB)
+ ;
+ mov ecx, 512
+pageTableEntries4kLoop:
+ mov eax, ecx
+ dec eax
+ shl eax, 12
+ add eax, GHCB_BASE & 0xFFE0_0000
+ add eax, PAGE_4K_PDE_ATTR
+ mov [ecx * 8 + GHCB_PT_ADDR - 8], eax
+ mov [(ecx * 8 + GHCB_PT_ADDR - 8) + 4], edx
+ loop pageTableEntries4kLoop
+
+ ;
+ ; Clear the encryption bit from the GHCB entry
+ ;
+ mov ecx, (GHCB_BASE & 0x1F_FFFF) >> 12
+ mov [ecx * 8 + GHCB_PT_ADDR + 4], strict dword 0
+
+ mov ecx, GHCB_SIZE / 4
+ xor eax, eax
+clearGhcbMemoryLoop:
+ mov dword[ecx * 4 + GHCB_BASE - 4], eax
+ loop clearGhcbMemoryLoop
+
+SetCr3:
;
; Set CR3 now that the paging structures are available
;
diff --git a/OvmfPkg/ResetVector/ResetVector.inf b/OvmfPkg/ResetVector/ResetVector.inf index b0ddfa5832..483fd90fe7 100644 --- a/OvmfPkg/ResetVector/ResetVector.inf +++ b/OvmfPkg/ResetVector/ResetVector.inf @@ -26,6 +26,7 @@ [Packages]
OvmfPkg/OvmfPkg.dec
MdePkg/MdePkg.dec
+ MdeModulePkg/MdeModulePkg.dec
UefiCpuPkg/UefiCpuPkg.dec
[BuildOptions]
@@ -33,5 +34,9 @@ *_*_X64_NASMB_FLAGS = -I$(WORKSPACE)/UefiCpuPkg/ResetVector/Vtf0/
[Pcd]
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbBase
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbSize
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbPageTableBase
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbPageTableSize
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPageTablesBase
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPageTablesSize
diff --git a/OvmfPkg/ResetVector/ResetVector.nasmb b/OvmfPkg/ResetVector/ResetVector.nasmb index 75cfe16654..bfb77e4391 100644 --- a/OvmfPkg/ResetVector/ResetVector.nasmb +++ b/OvmfPkg/ResetVector/ResetVector.nasmb @@ -53,8 +53,25 @@ %error "This implementation inherently depends on PcdOvmfSecPageTablesSize"
%endif
+ %if (FixedPcdGet32 (PcdOvmfSecGhcbPageTableSize) != 0x1000)
+ %error "This implementation inherently depends on PcdOvmfSecGhcbPageTableSize"
+ %endif
+
+ %if (FixedPcdGet32 (PcdOvmfSecGhcbSize) != 0x2000)
+ %error "This implementation inherently depends on PcdOvmfSecGhcbSize"
+ %endif
+
+ %if ((FixedPcdGet32 (PcdOvmfSecGhcbBase) >> 21) != \
+ ((FixedPcdGet32 (PcdOvmfSecGhcbBase) + FixedPcdGet32 (PcdOvmfSecGhcbSize) - 1) >> 21))
+ %error "This implementation inherently depends on PcdOvmfSecGhcbBase not straddling a 2MB boundary"
+ %endif
+
%define PT_ADDR(Offset) (FixedPcdGet32 (PcdOvmfSecPageTablesBase) + (Offset))
%include "Ia32/Flat32ToFlat64.asm"
+
+ %define GHCB_PT_ADDR (FixedPcdGet32 (PcdOvmfSecGhcbPageTableBase))
+ %define GHCB_BASE (FixedPcdGet32 (PcdOvmfSecGhcbBase))
+ %define GHCB_SIZE (FixedPcdGet32 (PcdOvmfSecGhcbSize))
%include "Ia32/PageTables64.asm"
%endif
|