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| author | Tom Lendacky <thomas.lendacky@amd.com> | 2021-01-07 12:48:19 -0600 |
|---|---|---|
| committer | mergify[bot] <37929162+mergify[bot]@users.noreply.github.com> | 2021-01-07 19:34:39 +0000 |
| commit | 31f5ebd6db0805cdcafb1312a91b60d14ff1ac24 (patch) | |
| tree | 996d42cb4d12db9f8474ba536049ca936ea448b3 /OvmfPkg | |
| parent | 84cddd70820f35e8bd0f169078765548eab3d3ca (diff) | |
| download | edk2-31f5ebd6db0805cdcafb1312a91b60d14ff1ac24.tar.gz edk2-31f5ebd6db0805cdcafb1312a91b60d14ff1ac24.tar.bz2 edk2-31f5ebd6db0805cdcafb1312a91b60d14ff1ac24.zip | |
OvmfPkg/VmgExitLib: Check for an explicit DR7 cached value
BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3108
Check the DR7 cached indicator against a specific value. This makes it
harder for a hypervisor to just write random data into that field in an
attempt to use an invalid DR7 value.
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <65157c1155a9c058c43678400dfc0b486e327a3e.1610045305.git.thomas.lendacky@amd.com>
Diffstat (limited to 'OvmfPkg')
| -rw-r--r-- | OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c index 1671db3a01..5149ab2bc9 100644 --- a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c +++ b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c @@ -128,10 +128,13 @@ UINT64 //
// Per-CPU data mapping structure
+// Use UINT32 for cached indicators and compare to a specific value
+// so that the hypervisor can't indicate a value is cached by just
+// writing random data to that area.
//
typedef struct {
- BOOLEAN Dr7Cached;
- UINT64 Dr7;
+ UINT32 Dr7Cached;
+ UINT64 Dr7;
} SEV_ES_PER_CPU_DATA;
@@ -1489,7 +1492,7 @@ Dr7WriteExit ( }
SevEsData->Dr7 = *Register;
- SevEsData->Dr7Cached = TRUE;
+ SevEsData->Dr7Cached = 1;
return 0;
}
@@ -1533,7 +1536,7 @@ Dr7ReadExit ( // If there is a cached valued for DR7, return that. Otherwise return the
// DR7 standard reset value of 0x400 (no debug breakpoints set).
//
- *Register = (SevEsData->Dr7Cached) ? SevEsData->Dr7 : 0x400;
+ *Register = (SevEsData->Dr7Cached == 1) ? SevEsData->Dr7 : 0x400;
return 0;
}
|