The branch stable/15 has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=532c8d3f90b95fb13b320cdfdc89e3d7d08875db
commit 532c8d3f90b95fb13b320cdfdc89e3d7d08875db Author: Konstantin Belousov <[email protected]> AuthorDate: 2024-10-24 02:12:25 +0000 Commit: Konstantin Belousov <[email protected]> CommitDate: 2026-02-18 08:00:04 +0000 amd64: add LASS support (cherry picked from commit 89589b6d3fbac43eb7c6b3cdbdd6f077888b2142) --- sys/amd64/amd64/efirt_machdep.c | 4 ++++ sys/amd64/amd64/initcpu.c | 13 +++++++++++++ sys/amd64/amd64/machdep.c | 1 + sys/amd64/amd64/pmap.c | 9 +++++++++ sys/amd64/include/md_var.h | 1 + 5 files changed, 28 insertions(+) diff --git a/sys/amd64/amd64/efirt_machdep.c b/sys/amd64/amd64/efirt_machdep.c index fe5d60c978dd..203b2b264587 100644 --- a/sys/amd64/amd64/efirt_machdep.c +++ b/sys/amd64/amd64/efirt_machdep.c @@ -348,6 +348,8 @@ efi_arch_enter(void) */ if (!pmap_pcid_enabled) invltlb(); + if (lass_enabled) + load_cr4(rcr4() & ~CR4_LASS); return (0); } @@ -357,6 +359,8 @@ efi_arch_leave(void) pmap_t curpmap; uint64_t cr3; + if (lass_enabled) + load_cr4(rcr4() | CR4_LASS); curpmap = &curproc->p_vmspace->vm_pmap; cr3 = curpmap->pm_cr3; if (pmap_pcid_enabled) { diff --git a/sys/amd64/amd64/initcpu.c b/sys/amd64/amd64/initcpu.c index 7f317674907e..4c57c27596ad 100644 --- a/sys/amd64/amd64/initcpu.c +++ b/sys/amd64/amd64/initcpu.c @@ -290,6 +290,19 @@ initializecpu(void) if (cpu_stdext_feature2 & CPUID_STDEXT2_PKU) cr4 |= CR4_PKE; + /* + * Any CPU having Linear Address Space Separation (LASS) + * should have SMAP, but check it to be sure. Otherwise + * userspace accesses from kernel cannot work. + */ + if (IS_BSP() && (cpu_stdext_feature4 & CPUID_STDEXT4_LASS) != 0 && + (cpu_stdext_feature & CPUID_STDEXT_SMAP) != 0) { + lass_enabled = 1; + TUNABLE_INT_FETCH("hw.lass", &lass_enabled); + } + if (lass_enabled) + cr4 |= CR4_LASS; + /* * If SMEP is present, we only need to flush RSB (by default) * on context switches, to prevent cross-process ret2spec diff --git a/sys/amd64/amd64/machdep.c b/sys/amd64/amd64/machdep.c index e56de986ccba..20d221279bd3 100644 --- a/sys/amd64/amd64/machdep.c +++ b/sys/amd64/amd64/machdep.c @@ -204,6 +204,7 @@ int cold = 1; long Maxmem = 0; long realmem = 0; int late_console = 1; +int lass_enabled = 0; struct kva_md_info kmi; diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c index 243a6625bece..8695dd61316e 100644 --- a/sys/amd64/amd64/pmap.c +++ b/sys/amd64/amd64/pmap.c @@ -1737,6 +1737,7 @@ pmap_bootstrap_la57(vm_paddr_t *firstaddr) { void (*la57_tramp)(uint64_t pml5); pml5_entry_t *pt; + uint64_t cr4; if ((cpu_stdext_feature2 & CPUID_STDEXT2_LA57) == 0) return; @@ -1757,8 +1758,16 @@ pmap_bootstrap_la57(vm_paddr_t *firstaddr) KERNSTART + amd64_loadaddr()); printf("Calling la57 trampoline at %p, KPML5phys %#lx ...", la57_tramp, KPML5phys); + if (lass_enabled) { + cr4 = rcr4(); + load_cr4(cr4 & ~CR4_LASS); + } la57_tramp(KPML5phys); printf(" alive in la57 mode\n"); + if (lass_enabled) { + cr4 = rcr4(); + load_cr4(cr4 | CR4_LASS); + } } static void diff --git a/sys/amd64/include/md_var.h b/sys/amd64/include/md_var.h index 19eab48168f7..7bb8ace27061 100644 --- a/sys/amd64/include/md_var.h +++ b/sys/amd64/include/md_var.h @@ -45,6 +45,7 @@ extern int hw_ibrs_disable; extern int hw_ssb_disable; extern int nmi_flush_l1d_sw; extern int syscall_ret_l1d_flush_mode; +extern int lass_enabled; extern vm_paddr_t intel_graphics_stolen_base; extern vm_paddr_t intel_graphics_stolen_size;
