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author | Gerd Hoffmann <kraxel@redhat.com> | 2024-02-14 11:45:03 +0100 |
---|---|---|
committer | mergify[bot] <37929162+mergify[bot]@users.noreply.github.com> | 2024-02-27 13:29:25 +0000 |
commit | 3ad1d7eb7bcb12d7b4967a27c6dec80395517797 (patch) | |
tree | f92f7260e66bfb840f7f5367457c6f7797de99db /OvmfPkg/PlatformPei | |
parent | 8757e648d11357b663331f6ed1cdb2ab017df178 (diff) | |
download | edk2-3ad1d7eb7bcb12d7b4967a27c6dec80395517797.zip edk2-3ad1d7eb7bcb12d7b4967a27c6dec80395517797.tar.gz edk2-3ad1d7eb7bcb12d7b4967a27c6dec80395517797.tar.bz2 |
OvmfPkg/PlatformPei: rewrite page table calculation
Consider 5-level paging. Simplify calculation to make it easier
to understand. Add some comments, improve ASSERTs.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20240214104504.2931339-4-kraxel@redhat.com>
Diffstat (limited to 'OvmfPkg/PlatformPei')
-rw-r--r-- | OvmfPkg/PlatformPei/MemDetect.c | 58 |
1 files changed, 36 insertions, 22 deletions
diff --git a/OvmfPkg/PlatformPei/MemDetect.c b/OvmfPkg/PlatformPei/MemDetect.c index d6c46ff..81c29c6 100644 --- a/OvmfPkg/PlatformPei/MemDetect.c +++ b/OvmfPkg/PlatformPei/MemDetect.c @@ -184,9 +184,12 @@ GetPeiMemoryCap ( BOOLEAN Page1GSupport;
UINT32 RegEax;
UINT32 RegEdx;
- UINT32 Pml4Entries;
- UINT32 PdpEntries;
- UINTN TotalPages;
+ UINT64 MaxAddr;
+ UINT32 Level5Pages;
+ UINT32 Level4Pages;
+ UINT32 Level3Pages;
+ UINT32 Level2Pages;
+ UINT32 TotalPages;
UINT64 ApStacks;
UINT64 MemoryCap;
@@ -203,8 +206,7 @@ GetPeiMemoryCap ( //
// Dependent on physical address width, PEI memory allocations can be
// dominated by the page tables built for 64-bit DXE. So we key the cap off
- // of those. The code below is based on CreateIdentityMappingPageTables() in
- // "MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c".
+ // of those.
//
Page1GSupport = FALSE;
if (PcdGetBool (PcdUse1GPageTable)) {
@@ -217,24 +219,36 @@ GetPeiMemoryCap ( }
}
- if (PlatformInfoHob->PhysMemAddressWidth <= 39) {
- Pml4Entries = 1;
- PdpEntries = 1 << (PlatformInfoHob->PhysMemAddressWidth - 30);
- ASSERT (PdpEntries <= 0x200);
- } else {
- if (PlatformInfoHob->PhysMemAddressWidth > 48) {
- Pml4Entries = 0x200;
- } else {
- Pml4Entries = 1 << (PlatformInfoHob->PhysMemAddressWidth - 39);
- }
+ //
+ // - A 4KB page accommodates the least significant 12 bits of the
+ // virtual address.
+ // - A page table entry at any level consumes 8 bytes, so a 4KB page
+ // table page (at any level) contains 512 entries, and
+ // accommodates 9 bits of the virtual address.
+ // - we minimally cover the phys address space with 2MB pages, so
+ // level 1 never exists.
+ // - If 1G paging is available, then level 2 doesn't exist either.
+ // - Start with level 2, where a page table page accommodates
+ // 9 + 9 + 12 = 30 bits of the virtual address (and covers 1GB of
+ // physical address space).
+ //
- ASSERT (Pml4Entries <= 0x200);
- PdpEntries = 512;
- }
+ MaxAddr = LShiftU64 (1, PlatformInfoHob->PhysMemAddressWidth);
+ Level2Pages = (UINT32)RShiftU64 (MaxAddr, 30);
+ Level3Pages = MAX (Level2Pages >> 9, 1u);
+ Level4Pages = MAX (Level3Pages >> 9, 1u);
+ Level5Pages = 1;
- TotalPages = Page1GSupport ? Pml4Entries + 1 :
- (PdpEntries + 1) * Pml4Entries + 1;
- ASSERT (TotalPages <= 0x40201);
+ if (Page1GSupport) {
+ Level2Pages = 0;
+ TotalPages = Level5Pages + Level4Pages + Level3Pages;
+ ASSERT (TotalPages <= 0x40201);
+ } else {
+ TotalPages = Level5Pages + Level4Pages + Level3Pages + Level2Pages;
+ // PlatformAddressWidthFromCpuid() caps at 40 phys bits without 1G pages.
+ ASSERT (PlatformInfoHob->PhysMemAddressWidth <= 40);
+ ASSERT (TotalPages <= 0x404);
+ }
//
// With 32k stacks and 4096 vcpus this lands at 128 MB (far away
@@ -247,7 +261,7 @@ GetPeiMemoryCap ( // PhysMemAddressWidth values close to 36 and a small number of
// CPUs, the cap will actually be dominated by this increment.
//
- MemoryCap = EFI_PAGES_TO_SIZE (TotalPages) + ApStacks + SIZE_64MB;
+ MemoryCap = EFI_PAGES_TO_SIZE ((UINTN)TotalPages) + ApStacks + SIZE_64MB;
ASSERT (MemoryCap <= MAX_UINT32);
return (UINT32)MemoryCap;
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