REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4614
About the IsModified, current function doesn't consider that hardware
also may change the pagetable. The issue is that in the first call of
internal function PageTableLibMapInLevel, the function assume page
table is not changed, and add ASSERT to check. But hardware may change
the page table, which cause the ASSERT happens.
Fix the issue by adding addtional condition to only check if the page
table is changed when the software want to modify the page table.
Also, add more comment to explain this behavior.
Cc: Ray Ni <ray...@intel.com>
Cc: Laszlo Ersek <ler...@redhat.com>
Cc: Rahul Kumar <rahul1.ku...@intel.com>
Cc: Gerd Hoffmann <kra...@redhat.com>
Cc: Crystal Lee <crystal...@ami.com.tw>
Cc: Pedro Falcato <pedro.falc...@gmail.com>
Signed-off-by: Zhiguang Liu <zhiguang....@intel.com>
---
.../Library/CpuPageTableLib/CpuPageTableMap.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)
diff --git a/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
b/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
index 36b2c4e6a3..ea6547970a 100644
--- a/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
+++ b/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
@@ -274,7 +274,7 @@ IsAttributesAndMaskValidForNonPresentEntry (
Page table entries that map the linear
address range are reset to 0 before set to the new attribute
when a new physical base address is set.
@param[in] Mask The mask used for attribute. The
corresponding field in Attribute is ignored if that in Mask is 0.
- @param[out] IsModified TRUE means page table is modified. FALSE
means page table is not modified.
+ @param[in, out] IsModified Change IsModified to True if page table is
modified and input parameter Modify is TRUE.
@retval RETURN_INVALID_PARAMETER For non-present range, Mask->Bits.Present
is 0 but some other attributes are provided.
@retval RETURN_INVALID_PARAMETER For non-present range, Mask->Bits.Present
is 1, Attribute->Bits.Present is 1 but some other attributes are not provided.
@@ -294,7 +294,7 @@ PageTableLibMapInLevel (
IN UINT64 Offset,
IN IA32_MAP_ATTRIBUTE *Attribute,
IN IA32_MAP_ATTRIBUTE *Mask,
- OUT BOOLEAN *IsModified
+ IN OUT BOOLEAN *IsModified
)
{
RETURN_STATUS Status;
@@ -567,7 +567,10 @@ PageTableLibMapInLevel (
OriginalCurrentPagingEntry.Uint64 = CurrentPagingEntry->Uint64;
PageTableLibSetPle (Level, CurrentPagingEntry, Offset, Attribute,
&CurrentMask);
- if (OriginalCurrentPagingEntry.Uint64 != CurrentPagingEntry->Uint64) {
+ if (Modify && (OriginalCurrentPagingEntry.Uint64 !=
CurrentPagingEntry->Uint64)) {
+ //
+ // The page table entry can be changed by this function only when
Modify is true.
+ //
*IsModified = TRUE;
}
}
@@ -609,7 +612,10 @@ PageTableLibMapInLevel (
// Check if ParentPagingEntry entry is modified here is enough. Except the
changes happen in leaf PagingEntry during
// the while loop, if there is any other change happens in page table, the
ParentPagingEntry must has been modified.
//
- if (OriginalParentPagingEntry.Uint64 != ParentPagingEntry->Uint64) {
+ if (Modify && (OriginalParentPagingEntry.Uint64 !=
ParentPagingEntry->Uint64)) {
+ //
+ // The page table entry can be changed by this function only when Modify
is true.
+ //
*IsModified = TRUE;
}
@@ -633,7 +639,9 @@ PageTableLibMapInLevel (
Page table entries that map the linear
address range are reset to 0 before set to the new attribute
when a new physical base address is set.
@param[in] Mask The mask used for attribute. The
corresponding field in Attribute is ignored if that in Mask is 0.
- @param[out] IsModified TRUE means page table is modified. FALSE
means page table is not modified.
+ @param[out] IsModified TRUE means page table is modified by software
or hardware. FALSE means page table is not modified by software.
+ If the output IsModified is FALSE, there is
possibility that the page table is changed by hardware. It is ok
+ because page table can be changed by hardware
anytime, and caller don't need to Flush TLB.
@retval RETURN_UNSUPPORTED PagingMode is not supported.
@retval RETURN_INVALID_PARAMETER PageTable, BufferSize, Attribute or Mask
is NULL.
--
2.31.1.windows.1
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