On 2/27/24 04:18, Gerd Hoffmann wrote:
On Thu, Feb 22, 2024 at 11:29:46AM -0600, Tom Lendacky wrote:
BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4654
The SNP_PAGE_STATE_MAX_ENTRY is based on the number of entries that can
fit in the GHCB shared buffer. As a result, the SNP_PAGE_STATE_CHANGE_INFO
structure maps the full GHCB shared buffer based on the shared buffer size
being 2032 bytes.
Instead of using a hardcoded value for SNP_PAGE_STATE_MAX_ENTRY, use a
build calculated value. Since the SNP_PAGE_STATE_CHANGE_INFO is used as a
mapping, eliminate the hardcoded array size so that the structure can be
used based on any size buffer.
Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com>
---
MdePkg/Include/Register/Amd/Ghcb.h | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/MdePkg/Include/Register/Amd/Ghcb.h
b/MdePkg/Include/Register/Amd/Ghcb.h
index 432d67e3e223..0cdc00627472 100644
--- a/MdePkg/Include/Register/Amd/Ghcb.h
+++ b/MdePkg/Include/Register/Amd/Ghcb.h
@@ -197,13 +197,14 @@ typedef struct {
UINT32 Reserved;
} SNP_PAGE_STATE_HEADER;
-#define SNP_PAGE_STATE_MAX_ENTRY 253
-
typedef struct {
SNP_PAGE_STATE_HEADER Header;
- SNP_PAGE_STATE_ENTRY Entry[SNP_PAGE_STATE_MAX_ENTRY];
+ SNP_PAGE_STATE_ENTRY Entry[];
} SNP_PAGE_STATE_CHANGE_INFO;
Good.
+#define SNP_PAGE_STATE_MAX_ENTRY \
+ ((sizeof (((GHCB *)0)->SharedBuffer) - sizeof (SNP_PAGE_STATE_HEADER)) /
sizeof (SNP_PAGE_STATE_ENTRY))
Can be dropped I think, after applying patch #6 BaseMemEncryptSevLib
does not use SNP_PAGE_STATE_MAX_ENTRY any more.
It gets used again in patch #9 for the exit optimization support.
Thanks,
Tom
take care,
Gerd
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