boot/bios_ia32: basic support la57 aka 5-level paging for x86_64 kernels

la57 kernel support is required. we simply add a 5th level and enable the cr4
feature. the safemode option "256tb_memory_limit" is named after the 4gb one,
but the current support is limited to 512GB as before (this can be later extended).

Change-Id: I922774473c4a6112a0e4ff74162285ad58aa53af
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3552
Reviewed-by: Adrien Destugues <[email protected]>
Reviewed-by: Axel Dörfler <[email protected]>

headers/private/system/safemode_defs.h

@@ -18,6 +18,7 @@
 #define B_SAFEMODE_DISABLE_HYPER_THREADING	"disable_hyperthreading"
 #define B_SAFEMODE_FAIL_SAFE_VIDEO_MODE		"fail_safe_video_mode"
 #define B_SAFEMODE_4_GB_MEMORY_LIMIT		"4gb_memory_limit"
+#define B_SAFEMODE_256_TB_MEMORY_LIMIT		"256tb_memory_limit"
 
 #if DEBUG_SPINLOCK_LATENCIES
 #	define B_SAFEMODE_DISABLE_LATENCY_CHECK	"disable_latency_check"

src/system/boot/platform/bios_ia32/long.cpp

@@ -21,6 +21,7 @@
 #include <boot/stage2.h>
 #include <boot/stdio.h>
 #include <kernel.h>
+#include <safemode.h>
 
 #include "debug.h"
 #include "mmu.h"
@@ -35,7 +36,8 @@ static const uint64 kPageMappingFlags = 0x103;
 extern "C" void long_enter_kernel(int currentCPU, uint64 stackTop);
 
 extern uint64 gLongGDT;
-extern uint32 gLongPhysicalPML4;
+extern uint32 gLongPhysicalPMLTop;
+extern bool gLongLA57;
 extern uint64 gLongKernelEntry;
 
 
@@ -88,16 +90,11 @@ long_gdt_init()
 static void
 long_mmu_init()
 {
-	uint64* pml4;
+	uint64* pmlTop;
-	uint64* pdpt;
+	// Allocate the top level PMLTop.
-	uint64* pageDir;
+	pmlTop = (uint64*)mmu_allocate_page(&gKernelArgs.arch_args.phys_pgdir);
-	uint64* pageTable;
+	memset(pmlTop, 0, B_PAGE_SIZE);
-	addr_t physicalAddress;
+	gKernelArgs.arch_args.vir_pgdir = fix_address((uint64)(addr_t)pmlTop);
-
-	// Allocate the top level PML4.
-	pml4 = (uint64*)mmu_allocate_page(&gKernelArgs.arch_args.phys_pgdir);
-	memset(pml4, 0, B_PAGE_SIZE);
-	gKernelArgs.arch_args.vir_pgdir = fix_address((uint64)(addr_t)pml4);
 
 	// Store the virtual memory usage information.
 	gKernelArgs.virtual_allocated_range[0].start = KERNEL_LOAD_BASE_64_BIT;
@@ -127,6 +124,29 @@ long_mmu_init()
 	if (maxAddress / 0x40000000 > 512)
 		panic("Can't currently support more than 512GB of RAM!");
 
+	uint64* pml4 = pmlTop;
+	addr_t physicalAddress;
+	cpuid_info info;
+	if (get_current_cpuid(&info, 7, 0) == B_OK
+		&& (info.regs.ecx & IA32_FEATURE_LA57) != 0) {
+
+		if (get_safemode_boolean(B_SAFEMODE_256_TB_MEMORY_LIMIT, false)) {
+			// LA57 has been disabled!
+			dprintf("la57 disabled per safemode setting\n");
+		} else {
+			dprintf("la57 enabled\n");
+			gLongLA57 = true;
+			pml4 = (uint64*)mmu_allocate_page(&physicalAddress);
+			memset(pml4, 0, B_PAGE_SIZE);
+			pmlTop[511] = physicalAddress | kTableMappingFlags;
+			pmlTop[0] = physicalAddress | kTableMappingFlags;
+		}
+	}
+
+	uint64* pdpt;
+	uint64* pageDir;
+	uint64* pageTable;
+
 	// Create page tables for the physical map area. Also map this PDPT
 	// temporarily at the bottom of the address space so that we are identity
 	// mapped.
@@ -151,7 +171,6 @@ long_mmu_init()
 	mmu_free(pdpt, B_PAGE_SIZE);
 
 	// Allocate tables for the kernel mappings.
-
 	pdpt = (uint64*)mmu_allocate_page(&physicalAddress);
 	memset(pdpt, 0, B_PAGE_SIZE);
 	pml4[511] = physicalAddress | kTableMappingFlags;
@@ -186,6 +205,8 @@ long_mmu_init()
 		mmu_free(pageTable, B_PAGE_SIZE);
 	mmu_free(pageDir, B_PAGE_SIZE);
 	mmu_free(pdpt, B_PAGE_SIZE);
+	if (pml4 != pmlTop)
+		mmu_free(pml4, B_PAGE_SIZE);
 
 	// Sort the address ranges.
 	sort_address_ranges(gKernelArgs.physical_memory_range,
@@ -216,7 +237,7 @@ long_mmu_init()
 			gKernelArgs.virtual_allocated_range[i].size);
 	}
 
-	gLongPhysicalPML4 = gKernelArgs.arch_args.phys_pgdir;
+	gLongPhysicalPMLTop = gKernelArgs.arch_args.phys_pgdir;
 }
 
 

src/system/boot/platform/bios_ia32/long_asm.S

@@ -27,6 +27,9 @@ FUNCTION(long_enter_kernel):
 	movl	8(%esp), %edi
 	movl	12(%esp), %esi
 
+	movl	gLongLA57, %ecx
+	shl		$12, %ecx
+
 	// Currently running with 32-bit paging tables at an identity mapped
 	// address. To switch to 64-bit paging we must first disable 32-bit paging,
 	// otherwise loading the new CR3 will fault.
@@ -34,13 +37,14 @@ FUNCTION(long_enter_kernel):
 	andl	$~(1 << 31), %eax
 	movl	%eax, %cr0
 
-	// Enable PAE and PGE
+	// Enable PAE and PGE, and optionally LA57
 	movl	%cr4, %eax
 	orl		$(1 << 5) | (1 << 7), %eax
+	orl		%ecx, %eax
 	movl	%eax, %cr4
 
-	// Point CR3 to the kernel's PML4.
+	// Point CR3 to the kernel's PMLTop.
-	movl	gLongPhysicalPML4, %eax
+	movl	gLongPhysicalPMLTop, %eax
 	movl	%eax, %cr3
 
 	// Enable long mode by setting EFER.LME.
@@ -97,7 +101,10 @@ long_gdtr:
 SYMBOL(gLongGDT):
 	.long	0
 
-SYMBOL(gLongPhysicalPML4):
+SYMBOL(gLongPhysicalPMLTop):
+	.long	0
+
+SYMBOL(gLongLA57):
 	.long	0
 
 SYMBOL(gLongKernelEntry):

src/system/boot/platform/bios_ia32/smp.cpp

@@ -589,16 +589,30 @@ smp_add_safemode_menus(Menu *menu)
 			item->SetHelpText("Disables using X2APIC.");
 		}
 
-		if (get_current_cpuid(&info, 7, 0) == B_OK
+		get_current_cpuid(&info, 0, 0);
-				&& (info.regs.ebx & (IA32_FEATURE_SMEP
+		uint32 maxBasicLeaf = info.eax_0.max_eax;
-					| IA32_FEATURE_SMAP)) != 0) {
+		if (maxBasicLeaf >= 7) {
-			menu->AddItem(item = new(nothrow) MenuItem(
+			if (get_current_cpuid(&info, 7, 0) == B_OK
-				"Disable SMEP and SMAP"));
+					&& (info.regs.ebx & (IA32_FEATURE_SMEP
-			item->SetType(MENU_ITEM_MARKABLE);
+						| IA32_FEATURE_SMAP)) != 0) {
-			item->SetData(B_SAFEMODE_DISABLE_SMEP_SMAP);
+				menu->AddItem(item = new(nothrow) MenuItem(
-			item->SetHelpText("Disables using SMEP and SMAP.");
+					"Disable SMEP and SMAP"));
-		}
+				item->SetType(MENU_ITEM_MARKABLE);
+				item->SetData(B_SAFEMODE_DISABLE_SMEP_SMAP);
+				item->SetHelpText("Disables using SMEP and SMAP.");
+			}
 
+			if (get_current_cpuid(&info, 7, 0) == B_OK
+					&& (info.regs.ecx & IA32_FEATURE_LA57) != 0) {
+				menu->AddItem(item = new(nothrow) MenuItem(
+					"Ignore memory beyond 256 TiB"));
+				item->SetType(MENU_ITEM_MARKABLE);
+				item->SetData(B_SAFEMODE_256_TB_MEMORY_LIMIT);
+				item->SetHelpText("Ignores all memory beyond the 256 TiB "
+					"address limit, overriding the setting in the kernel "
+					"settings file.");
+			}
+		}
 	}
 
 	if (gKernelArgs.num_cpus < 2)