From: "Roth, Michael via groups.io" <Michael.Roth=amd.com@groups.io>
To: <devel@edk2.groups.io>
Cc: Tom Lendacky <thomas.lendacky@amd.com>,
Erdem Aktas <erdemaktas@google.com>,
Jiewen Yao <jiewen.yao@intel.com>, Min Xu <min.m.xu@intel.com>,
Jianyong Wu <jianyong.wu@arm.com>,
Anatol Belski <anbelski@linux.microsoft.com>
Subject: [edk2-devel] [PATCH v2] OvmfPkg: Don't make APIC MMIO accesses with encryption bit set
Date: Fri, 26 Apr 2024 08:51:20 -0500 [thread overview]
Message-ID: <20240426135120.1943562-1-michael.roth@amd.com> (raw)
For the most part, OVMF will clear the encryption bit for MMIO regions,
but there is currently one known exception during SEC when the APIC
base address is accessed via MMIO with the encryption bit set for
SEV-ES/SEV-SNP guests. In the case of SEV-SNP, this requires special
handling on the hypervisor side which may not be available in the
future[1], so make the necessary changes in the SEC-configured page
table to clear the encryption bit for 4K region containing the APIC
base address.
Since CpuPageTableLib is used to handle the splitting, some additional
care must be taken to clear the C-bit in all non-leaf PTEs since the
library expects that to be the case. Add handling for that when setting
up the SEC page table.
While here, drop special handling for the APIC base address in the
SEV-ES/SNP #VC handler.
[1] https://lore.kernel.org/lkml/20240208002420.34mvemnzrwwsaesw@amd.com/#t
Suggested-by: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Min Xu <min.m.xu@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Jianyong Wu <jianyong.wu@arm.com>
Cc: Anatol Belski <anbelski@linux.microsoft.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
---
changes since v1:
- use CpuPageTableLib to handle splitting (Gerd, Tom)
OvmfPkg/AmdSev/AmdSevX64.fdf | 5 +-
OvmfPkg/Bhyve/BhyveX64.dsc | 1 +
OvmfPkg/CloudHv/CloudHvX64.fdf | 5 +-
OvmfPkg/Library/CcExitLib/CcExitVcHandler.c | 12 +----
OvmfPkg/Microvm/MicrovmX64.fdf | 3 ++
OvmfPkg/OvmfPkg.dec | 5 ++
OvmfPkg/OvmfPkgX64.fdf | 5 +-
OvmfPkg/ResetVector/Ia32/PageTables64.asm | 20 +++----
OvmfPkg/Sec/AmdSev.c | 58 +++++++++++++++++++++
OvmfPkg/Sec/AmdSev.h | 14 +++++
OvmfPkg/Sec/SecMain.c | 1 +
OvmfPkg/Sec/SecMain.inf | 3 ++
12 files changed, 108 insertions(+), 24 deletions(-)
diff --git a/OvmfPkg/AmdSev/AmdSevX64.fdf b/OvmfPkg/AmdSev/AmdSevX64.fdf
index d49555c6c8..595945181c 100644
--- a/OvmfPkg/AmdSev/AmdSevX64.fdf
+++ b/OvmfPkg/AmdSev/AmdSevX64.fdf
@@ -77,7 +77,10 @@ gUefiOvmfPkgTokenSpaceGuid.PcdSevLaunchSecretBase|gUefiOvmfPkgTokenSpaceGuid.Pcd
0x010C00|0x000400
gUefiOvmfPkgTokenSpaceGuid.PcdQemuHashTableBase|gUefiOvmfPkgTokenSpaceGuid.PcdQemuHashTableSize
-0x011000|0x00F000
+0x011000|0x001000
+gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecApicPageTableBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecApicPageTableSize
+
+0x012000|0x00E000
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamSize
0x020000|0x0E0000
diff --git a/OvmfPkg/Bhyve/BhyveX64.dsc b/OvmfPkg/Bhyve/BhyveX64.dsc
index 6f305d690d..78050959f8 100644
--- a/OvmfPkg/Bhyve/BhyveX64.dsc
+++ b/OvmfPkg/Bhyve/BhyveX64.dsc
@@ -174,6 +174,7 @@
PeiHardwareInfoLib|OvmfPkg/Library/HardwareInfoLib/PeiHardwareInfoLib.inf
DxeHardwareInfoLib|OvmfPkg/Library/HardwareInfoLib/DxeHardwareInfoLib.inf
ImagePropertiesRecordLib|MdeModulePkg/Library/ImagePropertiesRecordLib/ImagePropertiesRecordLib.inf
+ CpuPageTableLib|UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableLib.inf
CustomizedDisplayLib|MdeModulePkg/Library/CustomizedDisplayLib/CustomizedDisplayLib.inf
FrameBufferBltLib|MdeModulePkg/Library/FrameBufferBltLib/FrameBufferBltLib.inf
diff --git a/OvmfPkg/CloudHv/CloudHvX64.fdf b/OvmfPkg/CloudHv/CloudHvX64.fdf
index eae3ada191..3e6688b103 100644
--- a/OvmfPkg/CloudHv/CloudHvX64.fdf
+++ b/OvmfPkg/CloudHv/CloudHvX64.fdf
@@ -76,7 +76,10 @@ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfCpuidBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfCp
0x00F000|0x001000
gUefiOvmfPkgTokenSpaceGuid.PcdXenPvhStartOfDayStructPtr|gUefiOvmfPkgTokenSpaceGuid.PcdXenPvhStartOfDayStructPtrSize
-0x010000|0x010000
+0x010000|0x001000
+gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecApicPageTableBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecApicPageTableSize
+
+0x011000|0x00F000
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamSize
0x020000|0x0E0000
diff --git a/OvmfPkg/Library/CcExitLib/CcExitVcHandler.c b/OvmfPkg/Library/CcExitLib/CcExitVcHandler.c
index 549375dfed..da8f1e5db9 100644
--- a/OvmfPkg/Library/CcExitLib/CcExitVcHandler.c
+++ b/OvmfPkg/Library/CcExitLib/CcExitVcHandler.c
@@ -98,7 +98,7 @@ UnsupportedExit (
Validate that the MMIO memory access is not to encrypted memory.
Examine the pagetable entry for the memory specified. MMIO should not be
- performed against encrypted memory. MMIO to the APIC page is always allowed.
+ performed against encrypted memory.
@param[in] Ghcb Pointer to the Guest-Hypervisor Communication Block
@param[in] MemoryAddress Memory address to validate
@@ -118,16 +118,6 @@ ValidateMmioMemory (
{
MEM_ENCRYPT_SEV_ADDRESS_RANGE_STATE State;
GHCB_EVENT_INJECTION GpEvent;
- UINTN Address;
-
- //
- // Allow APIC accesses (which will have the encryption bit set during
- // SEC and PEI phases).
- //
- Address = MemoryAddress & ~(SIZE_4KB - 1);
- if (Address == GetLocalApicBaseAddress ()) {
- return 0;
- }
State = MemEncryptSevGetAddressRangeState (
0,
diff --git a/OvmfPkg/Microvm/MicrovmX64.fdf b/OvmfPkg/Microvm/MicrovmX64.fdf
index 825bf9f5e4..055e659a35 100644
--- a/OvmfPkg/Microvm/MicrovmX64.fdf
+++ b/OvmfPkg/Microvm/MicrovmX64.fdf
@@ -62,6 +62,9 @@ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfWorkAreaBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvm
0x00C000|0x001000
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbBackupBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbBackupSize
+0x00D000|0x001000
+gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecApicPageTableBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecApicPageTableSize
+
0x010000|0x010000
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamSize
diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
index 2f7bded926..b23219ebd4 100644
--- a/OvmfPkg/OvmfPkg.dec
+++ b/OvmfPkg/OvmfPkg.dec
@@ -277,6 +277,11 @@
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbBackupBase|0|UINT32|0x44
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbBackupSize|0|UINT32|0x45
+ ## Specify the extra page table needed to mark the APIC MMIO range as unencrypted.
+ # The value should be a multiple of 4KB for each.
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecApicPageTableBase|0x0|UINT32|0x72
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecApicPageTableSize|0x0|UINT32|0x73
+
## The base address and size of the SEV Launch Secret Area provisioned
# after remote attestation. If this is set in the .fdf, the platform
# is responsible for protecting the area from DXE phase overwrites.
diff --git a/OvmfPkg/OvmfPkgX64.fdf b/OvmfPkg/OvmfPkgX64.fdf
index c2d3cc901e..b6e8f43566 100644
--- a/OvmfPkg/OvmfPkgX64.fdf
+++ b/OvmfPkg/OvmfPkgX64.fdf
@@ -97,7 +97,10 @@ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfCpuidBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfCp
0x00F000|0x001000
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecSvsmCaaBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecSvsmCaaSize
-0x010000|0x010000
+0x010000|0x001000
+gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecApicPageTableBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecApicPageTableSize
+
+0x011000|0x00F000
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamSize
0x020000|0x0E0000
diff --git a/OvmfPkg/ResetVector/Ia32/PageTables64.asm b/OvmfPkg/ResetVector/Ia32/PageTables64.asm
index 474d22dbfa..d913a39d46 100644
--- a/OvmfPkg/ResetVector/Ia32/PageTables64.asm
+++ b/OvmfPkg/ResetVector/Ia32/PageTables64.asm
@@ -67,7 +67,7 @@ BITS 32
;
; Create page tables for 4-level paging
;
-; Argument: upper 32 bits of the page table entries
+; Argument: upper 32 bits of the leaf page table entries
;
%macro CreatePageTables4Level 1
@@ -78,19 +78,19 @@ BITS 32
; Top level Page Directory Pointers (1 * 512GB entry)
;
mov dword[PT_ADDR (0)], PT_ADDR (0x1000) + PAGE_PDE_DIRECTORY_ATTR
- mov dword[PT_ADDR (4)], %1
+ mov dword[PT_ADDR (4)], 0
;
; Next level Page Directory Pointers (4 * 1GB entries => 4GB)
;
mov dword[PT_ADDR (0x1000)], PT_ADDR (0x2000) + PAGE_PDE_DIRECTORY_ATTR
- mov dword[PT_ADDR (0x1004)], %1
+ mov dword[PT_ADDR (0x1004)], 0
mov dword[PT_ADDR (0x1008)], PT_ADDR (0x3000) + PAGE_PDE_DIRECTORY_ATTR
- mov dword[PT_ADDR (0x100C)], %1
+ mov dword[PT_ADDR (0x100C)], 0
mov dword[PT_ADDR (0x1010)], PT_ADDR (0x4000) + PAGE_PDE_DIRECTORY_ATTR
- mov dword[PT_ADDR (0x1014)], %1
+ mov dword[PT_ADDR (0x1014)], 0
mov dword[PT_ADDR (0x1018)], PT_ADDR (0x5000) + PAGE_PDE_DIRECTORY_ATTR
- mov dword[PT_ADDR (0x101C)], %1
+ mov dword[PT_ADDR (0x101C)], 0
;
; Page Table Entries (2048 * 2MB entries => 4GB)
@@ -141,7 +141,7 @@ BITS 32
;
; Create page tables for 5-level paging with gigabyte pages
;
-; Argument: upper 32 bits of the page table entries
+; Argument: upper 32 bits of the leaf page table entries
;
; We have 6 pages available for the early page tables,
; we use four of them:
@@ -164,15 +164,15 @@ BITS 32
; level 5
mov dword[PT_ADDR (0)], PT_ADDR (0x1000) + PAGE_PDE_DIRECTORY_ATTR
- mov dword[PT_ADDR (4)], %1
+ mov dword[PT_ADDR (4)], 0
; level 4
mov dword[PT_ADDR (0x1000)], PT_ADDR (0x3000) + PAGE_PDE_DIRECTORY_ATTR
- mov dword[PT_ADDR (0x1004)], %1
+ mov dword[PT_ADDR (0x1004)], 0
; level 3 (1x -> level 2, 3x 1GB)
mov dword[PT_ADDR (0x3000)], PT_ADDR (0x2000) + PAGE_PDE_DIRECTORY_ATTR
- mov dword[PT_ADDR (0x3004)], %1
+ mov dword[PT_ADDR (0x3004)], 0
mov dword[PT_ADDR (0x3008)], (1 << 30) + PAGE_PDE_LARGEPAGE_ATTR
mov dword[PT_ADDR (0x300c)], %1
mov dword[PT_ADDR (0x3010)], (2 << 30) + PAGE_PDE_LARGEPAGE_ATTR
diff --git a/OvmfPkg/Sec/AmdSev.c b/OvmfPkg/Sec/AmdSev.c
index 520b125132..89fba2fd18 100644
--- a/OvmfPkg/Sec/AmdSev.c
+++ b/OvmfPkg/Sec/AmdSev.c
@@ -8,7 +8,10 @@
**/
#include <Library/BaseLib.h>
+#include <Library/CpuLib.h>
+#include <Library/CpuPageTableLib.h>
#include <Library/DebugLib.h>
+#include <Library/LocalApicLib.h>
#include <Library/MemEncryptSevLib.h>
#include <Library/BaseMemoryLib.h>
#include <Register/Amd/Ghcb.h>
@@ -301,3 +304,58 @@ SecValidateSystemRam (
MemEncryptSevSnpPreValidateSystemRam (Start, EFI_SIZE_TO_PAGES ((UINTN)(End - Start)));
}
}
+
+/**
+ Map known MMIO regions unencrypted if SEV-ES is active.
+
+ During early booting, page table entries default to having the encryption bit
+ set for SEV-ES/SEV-SNP guests. In cases where there is MMIO to an address, the
+ encryption bit should be cleared. Clear it here for any known MMIO accesses
+ during SEC, which is currently just the APIC base address.
+
+**/
+VOID
+SecMapApicBaseUnencrypted (
+ VOID
+ )
+{
+ PHYSICAL_ADDRESS Cr3;
+ UINT64 ApicAddress;
+ VOID *Buffer;
+ UINTN BufferSize;
+ IA32_MAP_ATTRIBUTE MapAttribute;
+ IA32_MAP_ATTRIBUTE MapMask;
+ RETURN_STATUS Status;
+
+ if (!SevEsIsEnabled ()) {
+ return;
+ }
+
+ ApicAddress = (UINT64)GetLocalApicBaseAddress ();
+ Buffer = (VOID *)(UINTN)FixedPcdGet32 (PcdOvmfSecApicPageTableBase);
+ Cr3 = AsmReadCr3 ();
+
+ MapAttribute.Uint64 = ApicAddress;
+ MapAttribute.Bits.Present = 1;
+ MapAttribute.Bits.ReadWrite = 1;
+ MapMask.Uint64 = MAX_UINT64;
+ BufferSize = SIZE_4KB;
+
+ Status = PageTableMap (
+ (UINTN *)&Cr3,
+ Paging4Level,
+ Buffer,
+ &BufferSize,
+ ApicAddress,
+ SIZE_4KB,
+ &MapAttribute,
+ &MapMask,
+ NULL
+ );
+ if (RETURN_ERROR (Status)) {
+ DEBUG ((DEBUG_ERROR, "Failed to map APIC MMIO region as unencrypted: %d\n", Status));
+ ASSERT (FALSE);
+ }
+
+ CpuFlushTlb ();
+}
diff --git a/OvmfPkg/Sec/AmdSev.h b/OvmfPkg/Sec/AmdSev.h
index f75877096e..c5ab0d5a0b 100644
--- a/OvmfPkg/Sec/AmdSev.h
+++ b/OvmfPkg/Sec/AmdSev.h
@@ -91,4 +91,18 @@ SevSnpIsEnabled (
VOID
);
+/**
+ Map MMIO regions unencrypted if SEV-ES is active.
+
+ During early booting, page table entries default to having the encryption bit
+ set for SEV-ES/SEV-SNP guests. In cases where there is MMIO to an address, the
+ encryption bit should be cleared. Clear it here for any known MMIO accesses
+ during SEC, which is currently just the APIC base address.
+
+**/
+VOID
+SecMapApicBaseUnencrypted (
+ VOID
+ );
+
#endif
diff --git a/OvmfPkg/Sec/SecMain.c b/OvmfPkg/Sec/SecMain.c
index a30d4ce09e..60dfa61842 100644
--- a/OvmfPkg/Sec/SecMain.c
+++ b/OvmfPkg/Sec/SecMain.c
@@ -938,6 +938,7 @@ SecCoreStartupWithStack (
// interrupts before initializing the Debug Agent and the debug timer is
// enabled.
//
+ SecMapApicBaseUnencrypted ();
InitializeApicTimer (0, MAX_UINT32, TRUE, 5);
DisableApicTimerInterrupt ();
diff --git a/OvmfPkg/Sec/SecMain.inf b/OvmfPkg/Sec/SecMain.inf
index dca932a474..88c2d3fb6d 100644
--- a/OvmfPkg/Sec/SecMain.inf
+++ b/OvmfPkg/Sec/SecMain.inf
@@ -55,6 +55,7 @@
MemEncryptSevLib
CpuExceptionHandlerLib
CcProbeLib
+ CpuPageTableLib
[Ppis]
gEfiTemporaryRamSupportPpiGuid # PPI ALWAYS_PRODUCED
@@ -83,6 +84,8 @@
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbBackupBase
gUefiOvmfPkgTokenSpaceGuid.PcdTdxAcceptPageSize
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfWorkAreaBase
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecApicPageTableBase
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecApicPageTableSize
[FeaturePcd]
gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire
--
2.25.1
-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#118341): https://edk2.groups.io/g/devel/message/118341
Mute This Topic: https://groups.io/mt/105750506/7686176
Group Owner: devel+owner@edk2.groups.io
Unsubscribe: https://edk2.groups.io/g/devel/unsub [rebecca@openfw.io]
-=-=-=-=-=-=-=-=-=-=-=-
next reply other threads:[~2024-04-26 13:51 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-26 13:51 Roth, Michael via groups.io [this message]
[not found] <17C9D8CD7CA10EA1.16940@groups.io>
2024-04-26 14:16 ` [edk2-devel] [PATCH v2] OvmfPkg: Don't make APIC MMIO accesses with encryption bit set Roth, Michael via groups.io
2024-04-26 15:25 ` Ard Biesheuvel
2024-04-26 19:51 ` Roth, Michael via groups.io
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-list from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20240426135120.1943562-1-michael.roth@amd.com \
--to=devel@edk2.groups.io \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox