git: 4e1d69b9fbff - main - amd64: switch to la57 mode before creating kernel page tables
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Date: Fri, 27 Jun 2025 05:43:37 UTC
The branch main has been updated by kib:
URL: https://cgit.FreeBSD.org/src/commit/?id=4e1d69b9fbff280962e5ae5258624b60d5ab4618
commit 4e1d69b9fbff280962e5ae5258624b60d5ab4618
Author: Konstantin Belousov <kib@FreeBSD.org>
AuthorDate: 2025-06-23 23:20:56 +0000
Commit: Konstantin Belousov <kib@FreeBSD.org>
CommitDate: 2025-06-27 04:23:20 +0000
amd64: switch to la57 mode before creating kernel page tables
Reviewed by: markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D51053
---
sys/amd64/amd64/locore.S | 2 +
sys/amd64/amd64/pmap.c | 209 ++++++++++++++++-------------------------------
2 files changed, 73 insertions(+), 138 deletions(-)
diff --git a/sys/amd64/amd64/locore.S b/sys/amd64/amd64/locore.S
index 29fbf38cea33..2be555b25160 100644
--- a/sys/amd64/amd64/locore.S
+++ b/sys/amd64/amd64/locore.S
@@ -119,6 +119,8 @@ ENTRY(la57_trampoline)
leaq la57_trampoline_end(%rip),%rsp /* priv stack */
movq %cr0,%rbp
+ leaq la57_trampoline_gdt(%rip),%rax
+ movq %rax,la57_trampoline_gdt_desc+2(%rip)
lgdtq la57_trampoline_gdt_desc(%rip)
pushq $(2<<3)
diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
index 6d1c2d70d8c0..18bf2b4c92a1 100644
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -1684,12 +1684,44 @@ bootaddr_rwx(vm_paddr_t pa)
return (pg_nx);
}
+extern const char la57_trampoline[];
+
+static void
+pmap_bootstrap_la57(vm_paddr_t *firstaddr)
+{
+ void (*la57_tramp)(uint64_t pml5);
+ pml5_entry_t *pt;
+
+ if ((cpu_stdext_feature2 & CPUID_STDEXT2_LA57) == 0)
+ return;
+ la57 = 1;
+ TUNABLE_INT_FETCH("vm.pmap.la57", &la57);
+ if (!la57)
+ return;
+
+ KPML5phys = allocpages(firstaddr, 1);
+ KPML4phys = rcr3() & 0xfffff000; /* pml4 from loader must be < 4G */
+
+ pt = (pml5_entry_t *)KPML5phys;
+ pt[0] = KPML4phys | X86_PG_V | X86_PG_RW | X86_PG_A | X86_PG_M;
+ pt[NPML4EPG - 1] = KPML4phys | X86_PG_V | X86_PG_RW | X86_PG_A |
+ X86_PG_M;
+
+ la57_tramp = (void (*)(uint64_t))((uintptr_t)la57_trampoline -
+ KERNSTART + amd64_loadaddr());
+ printf("Calling la57 trampoline at %p, KPML5phys %#lx ...",
+ la57_tramp, KPML5phys);
+ la57_tramp(KPML5phys);
+ printf(" alive in la57 mode\n");
+}
+
static void
create_pagetables(vm_paddr_t *firstaddr)
{
pd_entry_t *pd_p;
pdp_entry_t *pdp_p;
pml4_entry_t *p4_p;
+ pml5_entry_t *p5_p;
uint64_t DMPDkernphys;
vm_paddr_t pax;
#ifdef KASAN
@@ -1917,6 +1949,27 @@ create_pagetables(vm_paddr_t *firstaddr)
}
kernel_pml4 = (pml4_entry_t *)PHYS_TO_DMAP(KPML4phys);
+
+ if (la57) {
+ /* XXXKIB bootstrap KPML5phys page is lost */
+ KPML5phys = allocpages(firstaddr, 1);
+ for (i = 0, p5_p = (pml5_entry_t *)KPML5phys; i < NPML5EPG;
+ i++) {
+ if (i == PML5PML5I) {
+ /*
+ * Recursively map PML5 to itself in
+ * order to get PTmap and PDmap.
+ */
+ p5_p[i] = KPML5phys | X86_PG_RW | X86_PG_A |
+ X86_PG_M | X86_PG_V | pg_nx;
+ } else if (i == pmap_pml5e_index(UPT_MAX_ADDRESS)) {
+ p5_p[i] = KPML4phys | X86_PG_RW | X86_PG_A |
+ X86_PG_M | X86_PG_V;
+ } else {
+ p5_p[i] = 0;
+ }
+ }
+ }
TSEXIT();
}
@@ -1950,6 +2003,7 @@ pmap_bootstrap(vm_paddr_t *firstaddr)
/*
* Create an initial set of page tables to run the kernel in.
*/
+ pmap_bootstrap_la57(firstaddr);
create_pagetables(firstaddr);
pcpu0_phys = allocpages(firstaddr, 1);
@@ -1979,7 +2033,7 @@ pmap_bootstrap(vm_paddr_t *firstaddr)
cr4 = rcr4();
cr4 |= CR4_PGE;
load_cr4(cr4);
- load_cr3(KPML4phys);
+ load_cr3(la57 ? KPML5phys : KPML4phys);
if (cpu_stdext_feature & CPUID_STDEXT_SMEP)
cr4 |= CR4_SMEP;
if (cpu_stdext_feature & CPUID_STDEXT_SMAP)
@@ -1992,8 +2046,20 @@ pmap_bootstrap(vm_paddr_t *firstaddr)
* later unmapped (using pmap_remove()) and freed.
*/
PMAP_LOCK_INIT(kernel_pmap);
- kernel_pmap->pm_pmltop = kernel_pml4;
- kernel_pmap->pm_cr3 = KPML4phys;
+ if (la57) {
+ vtoptem = ((1ul << (NPTEPGSHIFT + NPDEPGSHIFT + NPDPEPGSHIFT +
+ NPML4EPGSHIFT + NPML5EPGSHIFT)) - 1) << 3;
+ PTmap = (vm_offset_t)P5Tmap;
+ vtopdem = ((1ul << (NPDEPGSHIFT + NPDPEPGSHIFT +
+ NPML4EPGSHIFT + NPML5EPGSHIFT)) - 1) << 3;
+ PDmap = (vm_offset_t)P5Dmap;
+ kernel_pmap->pm_pmltop = (void *)PHYS_TO_DMAP(KPML5phys);
+ kernel_pmap->pm_cr3 = KPML5phys;
+ pmap_pt_page_count_adj(kernel_pmap, 1); /* top-level page */
+ } else {
+ kernel_pmap->pm_pmltop = kernel_pml4;
+ kernel_pmap->pm_cr3 = KPML4phys;
+ }
kernel_pmap->pm_ucr3 = PMAP_NO_CR3;
TAILQ_INIT(&kernel_pmap->pm_pvchunk);
kernel_pmap->pm_stats.resident_count = res;
@@ -2048,6 +2114,8 @@ pmap_bootstrap(vm_paddr_t *firstaddr)
/*
* Re-initialize PCPU area for BSP after switching.
* Make hardware use gdt and common_tss from the new PCPU.
+ * Also clears the usage of temporary gdt during switch to
+ * LA57 paging.
*/
STAILQ_INIT(&cpuhead);
wrmsr(MSR_GSBASE, (uint64_t)&__pcpu[0]);
@@ -2177,141 +2245,6 @@ pmap_page_alloc_below_4g(bool zeroed)
1, 0, (1ULL << 32), PAGE_SIZE, 0, VM_MEMATTR_DEFAULT));
}
-extern const char la57_trampoline[], la57_trampoline_gdt_desc[],
- la57_trampoline_gdt[], la57_trampoline_end[];
-
-static void
-pmap_bootstrap_la57(void *arg __unused)
-{
- char *v_code;
- pml5_entry_t *v_pml5;
- pml4_entry_t *v_pml4;
- pdp_entry_t *v_pdp;
- pd_entry_t *v_pd;
- pt_entry_t *v_pt;
- vm_page_t m_code, m_pml4, m_pdp, m_pd, m_pt, m_pml5;
- void (*la57_tramp)(uint64_t pml5);
- struct region_descriptor r_gdt;
-
- if ((cpu_stdext_feature2 & CPUID_STDEXT2_LA57) == 0)
- return;
- la57 = 1;
- TUNABLE_INT_FETCH("vm.pmap.la57", &la57);
- if (!la57)
- return;
-
- r_gdt.rd_limit = NGDT * sizeof(struct user_segment_descriptor) - 1;
- r_gdt.rd_base = (long)__pcpu[0].pc_gdt;
-
- m_code = pmap_page_alloc_below_4g(true);
- v_code = (char *)PHYS_TO_DMAP(VM_PAGE_TO_PHYS(m_code));
- m_pml5 = pmap_page_alloc_below_4g(true);
- KPML5phys = VM_PAGE_TO_PHYS(m_pml5);
- v_pml5 = (pml5_entry_t *)PHYS_TO_DMAP(KPML5phys);
- m_pml4 = pmap_page_alloc_below_4g(true);
- v_pml4 = (pdp_entry_t *)PHYS_TO_DMAP(VM_PAGE_TO_PHYS(m_pml4));
- m_pdp = pmap_page_alloc_below_4g(true);
- v_pdp = (pdp_entry_t *)PHYS_TO_DMAP(VM_PAGE_TO_PHYS(m_pdp));
- m_pd = pmap_page_alloc_below_4g(true);
- v_pd = (pdp_entry_t *)PHYS_TO_DMAP(VM_PAGE_TO_PHYS(m_pd));
- m_pt = pmap_page_alloc_below_4g(true);
- v_pt = (pt_entry_t *)PHYS_TO_DMAP(VM_PAGE_TO_PHYS(m_pt));
-
- /*
- * Map m_code 1:1, it appears below 4G in KVA due to physical
- * address being below 4G. Since kernel KVA is in upper half,
- * the pml4e should be zero and free for temporary use.
- */
- kernel_pmap->pm_pmltop[pmap_pml4e_index(VM_PAGE_TO_PHYS(m_code))] =
- VM_PAGE_TO_PHYS(m_pdp) | X86_PG_V | X86_PG_RW | X86_PG_A |
- X86_PG_M;
- v_pdp[pmap_pdpe_index(VM_PAGE_TO_PHYS(m_code))] =
- VM_PAGE_TO_PHYS(m_pd) | X86_PG_V | X86_PG_RW | X86_PG_A |
- X86_PG_M;
- v_pd[pmap_pde_index(VM_PAGE_TO_PHYS(m_code))] =
- VM_PAGE_TO_PHYS(m_pt) | X86_PG_V | X86_PG_RW | X86_PG_A |
- X86_PG_M;
- v_pt[pmap_pte_index(VM_PAGE_TO_PHYS(m_code))] =
- VM_PAGE_TO_PHYS(m_code) | X86_PG_V | X86_PG_RW | X86_PG_A |
- X86_PG_M;
-
- /*
- * Add pml5 entry at top of KVA pointing to existing pml4 table,
- * entering all existing kernel mappings into level 5 table.
- */
- v_pml5[pmap_pml5e_index(UPT_MAX_ADDRESS)] = KPML4phys | X86_PG_V |
- X86_PG_RW | X86_PG_A | X86_PG_M;
-
- /*
- * Add pml5 entry for 1:1 trampoline mapping after LA57 is turned on.
- */
- v_pml5[pmap_pml5e_index(VM_PAGE_TO_PHYS(m_code))] =
- VM_PAGE_TO_PHYS(m_pml4) | X86_PG_V | X86_PG_RW | X86_PG_A |
- X86_PG_M;
- v_pml4[pmap_pml4e_index(VM_PAGE_TO_PHYS(m_code))] =
- VM_PAGE_TO_PHYS(m_pdp) | X86_PG_V | X86_PG_RW | X86_PG_A |
- X86_PG_M;
-
- /*
- * Copy and call the 48->57 trampoline, hope we return there, alive.
- */
- bcopy(la57_trampoline, v_code, la57_trampoline_end - la57_trampoline);
- *(u_long *)(v_code + 2 + (la57_trampoline_gdt_desc - la57_trampoline)) =
- la57_trampoline_gdt - la57_trampoline + VM_PAGE_TO_PHYS(m_code);
- la57_tramp = (void (*)(uint64_t))VM_PAGE_TO_PHYS(m_code);
- pmap_invalidate_all(kernel_pmap);
- if (bootverbose) {
- printf("entering LA57 trampoline at %#lx\n",
- (vm_offset_t)la57_tramp);
- }
- la57_tramp(KPML5phys);
-
- /*
- * gdt was necessary reset, switch back to our gdt.
- */
- lgdt(&r_gdt);
- wrmsr(MSR_GSBASE, (uint64_t)&__pcpu[0]);
- load_ds(_udatasel);
- load_es(_udatasel);
- load_fs(_ufssel);
- ssdtosyssd(&gdt_segs[GPROC0_SEL],
- (struct system_segment_descriptor *)&__pcpu[0].pc_gdt[GPROC0_SEL]);
- ltr(GSEL(GPROC0_SEL, SEL_KPL));
- lidt(&r_idt);
-
- if (bootverbose)
- printf("LA57 trampoline returned, CR4 %#lx\n", rcr4());
-
- /*
- * Now unmap the trampoline, and free the pages.
- * Clear pml5 entry used for 1:1 trampoline mapping.
- */
- pte_clear(&v_pml5[pmap_pml5e_index(VM_PAGE_TO_PHYS(m_code))]);
- invlpg((vm_offset_t)v_code);
- vm_page_free(m_code);
- vm_page_free(m_pdp);
- vm_page_free(m_pd);
- vm_page_free(m_pt);
-
- /*
- * Recursively map PML5 to itself in order to get PTmap and
- * PDmap.
- */
- v_pml5[PML5PML5I] = KPML5phys | X86_PG_RW | X86_PG_V | pg_nx;
-
- vtoptem = ((1ul << (NPTEPGSHIFT + NPDEPGSHIFT + NPDPEPGSHIFT +
- NPML4EPGSHIFT + NPML5EPGSHIFT)) - 1) << 3;
- PTmap = (vm_offset_t)P5Tmap;
- vtopdem = ((1ul << (NPDEPGSHIFT + NPDPEPGSHIFT +
- NPML4EPGSHIFT + NPML5EPGSHIFT)) - 1) << 3;
- PDmap = (vm_offset_t)P5Dmap;
-
- kernel_pmap->pm_cr3 = KPML5phys;
- kernel_pmap->pm_pmltop = v_pml5;
- pmap_pt_page_count_adj(kernel_pmap, 1);
-}
-SYSINIT(la57, SI_SUB_KMEM, SI_ORDER_ANY, pmap_bootstrap_la57, NULL);
-
/*
* Initialize a vm_page's machine-dependent fields.
*/