// SPDX-License-Identifier: GPL-2.0 /* * Core of Xen paravirt_ops implementation. * * This file contains the xen_paravirt_ops structure itself, and the * implementations for: * - privileged instructions * - interrupt flags * - segment operations * - booting and setup * * Jeremy Fitzhardinge , XenSource Inc, 2007 */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef CONFIG_X86_IOPL_IOPERM #include #endif #ifdef CONFIG_ACPI #include #include #include #include #include #endif #include "xen-ops.h" #include "mmu.h" #include "smp.h" #include "multicalls.h" #include "pmu.h" #include "../kernel/cpu/cpu.h" /* get_cpu_cap() */ void *xen_initial_gdt; static int xen_cpu_up_prepare_pv(unsigned int cpu); static int xen_cpu_dead_pv(unsigned int cpu); struct tls_descs { struct desc_struct desc[3]; }; /* * Updating the 3 TLS descriptors in the GDT on every task switch is * surprisingly expensive so we avoid updating them if they haven't * changed. Since Xen writes different descriptors than the one * passed in the update_descriptor hypercall we keep shadow copies to * compare against. */ static DEFINE_PER_CPU(struct tls_descs, shadow_tls_desc); static void __init xen_banner(void) { unsigned version = HYPERVISOR_xen_version(XENVER_version, NULL); struct xen_extraversion extra; HYPERVISOR_xen_version(XENVER_extraversion, &extra); pr_info("Booting paravirtualized kernel on %s\n", pv_info.name); printk(KERN_INFO "Xen version: %d.%d%s%s\n", version >> 16, version & 0xffff, extra.extraversion, xen_feature(XENFEAT_mmu_pt_update_preserve_ad) ? " (preserve-AD)" : ""); #ifdef CONFIG_X86_32 pr_warn("WARNING! WARNING! WARNING! WARNING! WARNING! WARNING! WARNING!\n" "Support for running as 32-bit PV-guest under Xen will soon be removed\n" "from the Linux kernel!\n" "Please use either a 64-bit kernel or switch to HVM or PVH mode!\n" "WARNING! WARNING! WARNING! WARNING! WARNING! WARNING! WARNING!\n"); #endif } static void __init xen_pv_init_platform(void) { populate_extra_pte(fix_to_virt(FIX_PARAVIRT_BOOTMAP)); set_fixmap(FIX_PARAVIRT_BOOTMAP, xen_start_info->shared_info); HYPERVISOR_shared_info = (void *)fix_to_virt(FIX_PARAVIRT_BOOTMAP); /* xen clock uses per-cpu vcpu_info, need to init it for boot cpu */ xen_vcpu_info_reset(0); /* pvclock is in shared info area */ xen_init_time_ops(); } static void __init xen_pv_guest_late_init(void) { #ifndef CONFIG_SMP /* Setup shared vcpu info for non-smp configurations */ xen_setup_vcpu_info_placement(); #endif } /* Check if running on Xen version (major, minor) or later */ bool xen_running_on_version_or_later(unsigned int major, unsigned int minor) { unsigned int version; if (!xen_domain()) return false; version = HYPERVISOR_xen_version(XENVER_version, NULL); if ((((version >> 16) == major) && ((version & 0xffff) >= minor)) || ((version >> 16) > major)) return true; return false; } static __read_mostly unsigned int cpuid_leaf5_ecx_val; static __read_mostly unsigned int cpuid_leaf5_edx_val; static void xen_cpuid(unsigned int *ax, unsigned int *bx, unsigned int *cx, unsigned int *dx) { unsigned maskebx = ~0; /* * Mask out inconvenient features, to try and disable as many * unsupported kernel subsystems as possible. */ switch (*ax) { case CPUID_MWAIT_LEAF: /* Synthesize the values.. */ *ax = 0; *bx = 0; *cx = cpuid_leaf5_ecx_val; *dx = cpuid_leaf5_edx_val; return; case 0xb: /* Suppress extended topology stuff */ maskebx = 0; break; } asm(XEN_EMULATE_PREFIX "cpuid" : "=a" (*ax), "=b" (*bx), "=c" (*cx), "=d" (*dx) : "0" (*ax), "2" (*cx)); *bx &= maskebx; } STACK_FRAME_NON_STANDARD(xen_cpuid); /* XEN_EMULATE_PREFIX */ static bool __init xen_check_mwait(void) { #ifdef CONFIG_ACPI struct xen_platform_op op = { .cmd = XENPF_set_processor_pminfo, .u.set_pminfo.id = -1, .u.set_pminfo.type = XEN_PM_PDC, }; uint32_t buf[3]; unsigned int ax, bx, cx, dx; unsigned int mwait_mask; /* We need to determine whether it is OK to expose the MWAIT * capability to the kernel to harvest deeper than C3 states from ACPI * _CST using the processor_harvest_xen.c module. For this to work, we * need to gather the MWAIT_LEAF values (which the cstate.c code * checks against). The hypervisor won't expose the MWAIT flag because * it would break backwards compatibility; so we will find out directly * from the hardware and hypercall. */ if (!xen_initial_domain()) return false; /* * When running under platform earlier than Xen4.2, do not expose * mwait, to avoid the risk of loading native acpi pad driver */ if (!xen_running_on_version_or_later(4, 2)) return false; ax = 1; cx = 0; native_cpuid(&ax, &bx, &cx, &dx); mwait_mask = (1 << (X86_FEATURE_EST % 32)) | (1 << (X86_FEATURE_MWAIT % 32)); if ((cx & mwait_mask) != mwait_mask) return false; /* We need to emulate the MWAIT_LEAF and for that we need both * ecx and edx. The hypercall provides only partial information. */ ax = CPUID_MWAIT_LEAF; bx = 0; cx = 0; dx = 0; native_cpuid(&ax, &bx, &cx, &dx); /* Ask the Hypervisor whether to clear ACPI_PDC_C_C2C3_FFH. If so, * don't expose MWAIT_LEAF and let ACPI pick the IOPORT version of C3. */ buf[0] = ACPI_PDC_REVISION_ID; buf[1] = 1; buf[2] = (ACPI_PDC_C_CAPABILITY_SMP | ACPI_PDC_EST_CAPABILITY_SWSMP); set_xen_guest_handle(op.u.set_pminfo.pdc, buf); if ((HYPERVISOR_platform_op(&op) == 0) && (buf[2] & (ACPI_PDC_C_C1_FFH | ACPI_PDC_C_C2C3_FFH))) { cpuid_leaf5_ecx_val = cx; cpuid_leaf5_edx_val = dx; } return true; #else return false; #endif } static bool __init xen_check_xsave(void) { unsigned int cx, xsave_mask; cx = cpuid_ecx(1); xsave_mask = (1 << (X86_FEATURE_XSAVE % 32)) | (1 << (X86_FEATURE_OSXSAVE % 32)); /* Xen will set CR4.OSXSAVE if supported and not disabled by force */ return (cx & xsave_mask) == xsave_mask; } static void __init xen_init_capabilities(void) { setup_force_cpu_cap(X86_FEATURE_XENPV); setup_clear_cpu_cap(X86_FEATURE_DCA); setup_clear_cpu_cap(X86_FEATURE_APERFMPERF); setup_clear_cpu_cap(X86_FEATURE_MTRR); setup_clear_cpu_cap(X86_FEATURE_ACC); setup_clear_cpu_cap(X86_FEATURE_X2APIC); setup_clear_cpu_cap(X86_FEATURE_SME); /* * Xen PV would need some work to support PCID: CR3 handling as well * as xen_flush_tlb_others() would need updating. */ setup_clear_cpu_cap(X86_FEATURE_PCID); if (!xen_initial_domain()) setup_clear_cpu_cap(X86_FEATURE_ACPI); if (xen_check_mwait()) setup_force_cpu_cap(X86_FEATURE_MWAIT); else setup_clear_cpu_cap(X86_FEATURE_MWAIT); if (!xen_check_xsave()) { setup_clear_cpu_cap(X86_FEATURE_XSAVE); setup_clear_cpu_cap(X86_FEATURE_OSXSAVE); } } static void xen_set_debugreg(int reg, unsigned long val) { HYPERVISOR_set_debugreg(reg, val); } static unsigned long xen_get_debugreg(int reg) { return HYPERVISOR_get_debugreg(reg); } static void xen_end_context_switch(struct task_struct *next) { xen_mc_flush(); paravirt_end_context_switch(next); } static unsigned long xen_store_tr(void) { return 0; } /* * Set the page permissions for a particular virtual address. If the * address is a vmalloc mapping (or other non-linear mapping), then * find the linear mapping of the page and also set its protections to * match. */ static void set_aliased_prot(void *v, pgprot_t prot) { int level; pte_t *ptep; pte_t pte; unsigned long pfn; struct page *page; unsigned char dummy; ptep = lookup_address((unsigned long)v, &level); BUG_ON(ptep == NULL); pfn = pte_pfn(*ptep); page = pfn_to_page(pfn); pte = pfn_pte(pfn, prot); /* * Careful: update_va_mapping() will fail if the virtual address * we're poking isn't populated in the page tables. We don't * need to worry about the direct map (that's always in the page * tables), but we need to be careful about vmap space. In * particular, the top level page table can lazily propagate * entries between processes, so if we've switched mms since we * vmapped the target in the first place, we might not have the * top-level page table entry populated. * * We disable preemption because we want the same mm active when * we probe the target and when we issue the hypercall. We'll * have the same nominal mm, but if we're a kernel thread, lazy * mm dropping could change our pgd. * * Out of an abundance of caution, this uses __get_user() to fault * in the target address just in case there's some obscure case * in which the target address isn't readable. */ preempt_disable(); probe_kernel_read(&dummy, v, 1); if (HYPERVISOR_update_va_mapping((unsigned long)v, pte, 0)) BUG(); if (!PageHighMem(page)) { void *av = __va(PFN_PHYS(pfn)); if (av != v) if (HYPERVISOR_update_va_mapping((unsigned long)av, pte, 0)) BUG(); } else kmap_flush_unused(); preempt_enable(); } static void xen_alloc_ldt(struct desc_struct *ldt, unsigned entries) { const unsigned entries_per_page = PAGE_SIZE / LDT_ENTRY_SIZE; int i; /* * We need to mark the all aliases of the LDT pages RO. We * don't need to call vm_flush_aliases(), though, since that's * only responsible for flushing aliases out the TLBs, not the * page tables, and Xen will flush the TLB for us if needed. * * To avoid confusing future readers: none of this is necessary * to load the LDT. The hypervisor only checks this when the * LDT is faulted in due to subsequent descriptor access. */ for (i = 0; i < entries; i += entries_per_page) set_aliased_prot(ldt + i, PAGE_KERNEL_RO); } static void xen_free_ldt(struct desc_struct *ldt, unsigned entries) { const unsigned entries_per_page = PAGE_SIZE / LDT_ENTRY_SIZE; int i; for (i = 0; i < entries; i += entries_per_page) set_aliased_prot(ldt + i, PAGE_KERNEL); } static void xen_set_ldt(const void *addr, unsigned entries) { struct mmuext_op *op; struct multicall_space mcs = xen_mc_entry(sizeof(*op)); trace_xen_cpu_set_ldt(addr, entries); op = mcs.args; op->cmd = MMUEXT_SET_LDT; op->arg1.linear_addr = (unsigned long)addr; op->arg2.nr_ents = entries; MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF); xen_mc_issue(PARAVIRT_LAZY_CPU); } static void xen_load_gdt(const struct desc_ptr *dtr) { unsigned long va = dtr->address; unsigned int size = dtr->size + 1; unsigned long pfn, mfn; int level; pte_t *ptep; void *virt; /* @size should be at most GDT_SIZE which is smaller than PAGE_SIZE. */ BUG_ON(size > PAGE_SIZE); BUG_ON(va & ~PAGE_MASK); /* * The GDT is per-cpu and is in the percpu data area. * That can be virtually mapped, so we need to do a * page-walk to get the underlying MFN for the * hypercall. The page can also be in the kernel's * linear range, so we need to RO that mapping too. */ ptep = lookup_address(va, &level); BUG_ON(ptep == NULL); pfn = pte_pfn(*ptep); mfn = pfn_to_mfn(pfn); virt = __va(PFN_PHYS(pfn)); make_lowmem_page_readonly((void *)va); make_lowmem_page_readonly(virt); if (HYPERVISOR_set_gdt(&mfn, size / sizeof(struct desc_struct))) BUG(); } /* * load_gdt for early boot, when the gdt is only mapped once */ static void __init xen_load_gdt_boot(const struct desc_ptr *dtr) { unsigned long va = dtr->address; unsigned int size = dtr->size + 1; unsigned long pfn, mfn; pte_t pte; /* @size should be at most GDT_SIZE which is smaller than PAGE_SIZE. */ BUG_ON(size > PAGE_SIZE); BUG_ON(va & ~PAGE_MASK); pfn = virt_to_pfn(va); mfn = pfn_to_mfn(pfn); pte = pfn_pte(pfn, PAGE_KERNEL_RO); if (HYPERVISOR_update_va_mapping((unsigned long)va, pte, 0)) BUG(); if (HYPERVISOR_set_gdt(&mfn, size / sizeof(struct desc_struct))) BUG(); } static inline bool desc_equal(const struct desc_struct *d1, const struct desc_struct *d2) { return !memcmp(d1, d2, sizeof(*d1)); } static void load_TLS_descriptor(struct thread_struct *t, unsigned int cpu, unsigned int i) { struct desc_struct *shadow = &per_cpu(shadow_tls_desc, cpu).desc[i]; struct desc_struct *gdt; xmaddr_t maddr; struct multicall_space mc; if (desc_equal(shadow, &t->tls_array[i])) return; *shadow = t->tls_array[i]; gdt = get_cpu_gdt_rw(cpu); maddr = arbitrary_virt_to_machine(&gdt[GDT_ENTRY_TLS_MIN+i]); mc = __xen_mc_entry(0); MULTI_update_descriptor(mc.mc, maddr.maddr, t->tls_array[i]); } static void xen_load_tls(struct thread_struct *t, unsigned int cpu) { /* * XXX sleazy hack: If we're being called in a lazy-cpu zone * and lazy gs handling is enabled, it means we're in a * context switch, and %gs has just been saved. This means we * can zero it out to prevent faults on exit from the * hypervisor if the next process has no %gs. Either way, it * has been saved, and the new value will get loaded properly. * This will go away as soon as Xen has been modified to not * save/restore %gs for normal hypercalls. * * On x86_64, this hack is not used for %gs, because gs points * to KERNEL_GS_BASE (and uses it for PDA references), so we * must not zero %gs on x86_64 * * For x86_64, we need to zero %fs, otherwise we may get an * exception between the new %fs descriptor being loaded and * %fs being effectively cleared at __switch_to(). */ if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_CPU) { #ifdef CONFIG_X86_32 lazy_load_gs(0); #else loadsegment(fs, 0); #endif } xen_mc_batch(); load_TLS_descriptor(t, cpu, 0); load_TLS_descriptor(t, cpu, 1); load_TLS_descriptor(t, cpu, 2); xen_mc_issue(PARAVIRT_LAZY_CPU); } #ifdef CONFIG_X86_64 static void xen_load_gs_index(unsigned int idx) { if (HYPERVISOR_set_segment_base(SEGBASE_GS_USER_SEL, idx)) BUG(); } #endif static void xen_write_ldt_entry(struct desc_struct *dt, int entrynum, const void *ptr) { xmaddr_t mach_lp = arbitrary_virt_to_machine(&dt[entrynum]); u64 entry = *(u64 *)ptr; trace_xen_cpu_write_ldt_entry(dt, entrynum, entry); preempt_disable(); xen_mc_flush(); if (HYPERVISOR_update_descriptor(mach_lp.maddr, entry)) BUG(); preempt_enable(); } #ifdef CONFIG_X86_64 struct trap_array_entry { void (*orig)(void); void (*xen)(void); bool ist_okay; }; #define TRAP_ENTRY(func, ist_ok) { \ .orig = asm_##func, \ .xen = xen_asm_##func, \ .ist_okay = ist_ok } static struct trap_array_entry trap_array[] = { { debug, xen_xendebug, true }, { double_fault, xen_double_fault, true }, #ifdef CONFIG_X86_MCE { machine_check, xen_machine_check, true }, #endif { nmi, xen_xennmi, true }, { int3, xen_int3, false }, TRAP_ENTRY(exc_overflow, false ), #ifdef CONFIG_IA32_EMULATION { entry_INT80_compat, xen_entry_INT80_compat, false }, #endif { page_fault, xen_page_fault, false }, TRAP_ENTRY(exc_divide_error, false ), TRAP_ENTRY(exc_bounds, false ), TRAP_ENTRY(exc_invalid_op, false ), TRAP_ENTRY(exc_device_not_available, false ), TRAP_ENTRY(exc_coproc_segment_overrun, false ), TRAP_ENTRY(exc_invalid_tss, false ), TRAP_ENTRY(exc_segment_not_present, false ), TRAP_ENTRY(exc_stack_segment, false ), TRAP_ENTRY(exc_general_protection, false ), TRAP_ENTRY(exc_spurious_interrupt_bug, false ), { coprocessor_error, xen_coprocessor_error, false }, { alignment_check, xen_alignment_check, false }, { simd_coprocessor_error, xen_simd_coprocessor_error, false }, }; static bool __ref get_trap_addr(void **addr, unsigned int ist) { unsigned int nr; bool ist_okay = false; /* * Replace trap handler addresses by Xen specific ones. * Check for known traps using IST and whitelist them. * The debugger ones are the only ones we care about. * Xen will handle faults like double_fault, * so we should never see * them. Warn if there's an unexpected IST-using fault handler. */ for (nr = 0; nr < ARRAY_SIZE(trap_array); nr++) { struct trap_array_entry *entry = trap_array + nr; if (*addr == entry->orig) { *addr = entry->xen; ist_okay = entry->ist_okay; break; } } if (nr == ARRAY_SIZE(trap_array) && *addr >= (void *)early_idt_handler_array[0] && *addr < (void *)early_idt_handler_array[NUM_EXCEPTION_VECTORS]) { nr = (*addr - (void *)early_idt_handler_array[0]) / EARLY_IDT_HANDLER_SIZE; *addr = (void *)xen_early_idt_handler_array[nr]; } if (WARN_ON(ist != 0 && !ist_okay)) return false; return true; } #endif static int cvt_gate_to_trap(int vector, const gate_desc *val, struct trap_info *info) { unsigned long addr; if (val->bits.type != GATE_TRAP && val->bits.type != GATE_INTERRUPT) return 0; info->vector = vector; addr = gate_offset(val); #ifdef CONFIG_X86_64 if (!get_trap_addr((void **)&addr, val->bits.ist)) return 0; #endif /* CONFIG_X86_64 */ info->address = addr; info->cs = gate_segment(val); info->flags = val->bits.dpl; /* interrupt gates clear IF */ if (val->bits.type == GATE_INTERRUPT) info->flags |= 1 << 2; return 1; } /* Locations of each CPU's IDT */ static DEFINE_PER_CPU(struct desc_ptr, idt_desc); /* Set an IDT entry. If the entry is part of the current IDT, then also update Xen. */ static void xen_write_idt_entry(gate_desc *dt, int entrynum, const gate_desc *g) { unsigned long p = (unsigned long)&dt[entrynum]; unsigned long start, end; trace_xen_cpu_write_idt_entry(dt, entrynum, g); preempt_disable(); start = __this_cpu_read(idt_desc.address); end = start + __this_cpu_read(idt_desc.size) + 1; xen_mc_flush(); native_write_idt_entry(dt, entrynum, g); if (p >= start && (p + 8) <= end) { struct trap_info info[2]; info[1].address = 0; if (cvt_gate_to_trap(entrynum, g, &info[0])) if (HYPERVISOR_set_trap_table(info)) BUG(); } preempt_enable(); } static void xen_convert_trap_info(const struct desc_ptr *desc, struct trap_info *traps) { unsigned in, out, count; count = (desc->size+1) / sizeof(gate_desc); BUG_ON(count > 256); for (in = out = 0; in < count; in++) { gate_desc *entry = (gate_desc *)(desc->address) + in; if (cvt_gate_to_trap(in, entry, &traps[out])) out++; } traps[out].address = 0; } void xen_copy_trap_info(struct trap_info *traps) { const struct desc_ptr *desc = this_cpu_ptr(&idt_desc); xen_convert_trap_info(desc, traps); } /* Load a new IDT into Xen. In principle this can be per-CPU, so we hold a spinlock to protect the static traps[] array (static because it avoids allocation, and saves stack space). */ static void xen_load_idt(const struct desc_ptr *desc) { static DEFINE_SPINLOCK(lock); static struct trap_info traps[257]; trace_xen_cpu_load_idt(desc); spin_lock(&lock); memcpy(this_cpu_ptr(&idt_desc), desc, sizeof(idt_desc)); xen_convert_trap_info(desc, traps); xen_mc_flush(); if (HYPERVISOR_set_trap_table(traps)) BUG(); spin_unlock(&lock); } /* Write a GDT descriptor entry. Ignore LDT descriptors, since they're handled differently. */ static void xen_write_gdt_entry(struct desc_struct *dt, int entry, const void *desc, int type) { trace_xen_cpu_write_gdt_entry(dt, entry, desc, type); preempt_disable(); switch (type) { case DESC_LDT: case DESC_TSS: /* ignore */ break; default: { xmaddr_t maddr = arbitrary_virt_to_machine(&dt[entry]); xen_mc_flush(); if (HYPERVISOR_update_descriptor(maddr.maddr, *(u64 *)desc)) BUG(); } } preempt_enable(); } /* * Version of write_gdt_entry for use at early boot-time needed to * update an entry as simply as possible. */ static void __init xen_write_gdt_entry_boot(struct desc_struct *dt, int entry, const void *desc, int type) { trace_xen_cpu_write_gdt_entry(dt, entry, desc, type); switch (type) { case DESC_LDT: case DESC_TSS: /* ignore */ break; default: { xmaddr_t maddr = virt_to_machine(&dt[entry]); if (HYPERVISOR_update_descriptor(maddr.maddr, *(u64 *)desc)) dt[entry] = *(struct desc_struct *)desc; } } } static void xen_load_sp0(unsigned long sp0) { struct multicall_space mcs; mcs = xen_mc_entry(0); MULTI_stack_switch(mcs.mc, __KERNEL_DS, sp0); xen_mc_issue(PARAVIRT_LAZY_CPU); this_cpu_write(cpu_tss_rw.x86_tss.sp0, sp0); } #ifdef CONFIG_X86_IOPL_IOPERM static void xen_update_io_bitmap(void) { struct physdev_set_iobitmap iobitmap; struct tss_struct *tss = this_cpu_ptr(&cpu_tss_rw); native_tss_update_io_bitmap(); iobitmap.bitmap = (uint8_t *)(&tss->x86_tss) + tss->x86_tss.io_bitmap_base; if (tss->x86_tss.io_bitmap_base == IO_BITMAP_OFFSET_INVALID) iobitmap.nr_ports = 0; else iobitmap.nr_ports = IO_BITMAP_BITS; HYPERVISOR_physdev_op(PHYSDEVOP_set_iobitmap, &iobitmap); } #endif static void xen_io_delay(void) { } static DEFINE_PER_CPU(unsigned long, xen_cr0_value); static unsigned long xen_read_cr0(void) { unsigned long cr0 = this_cpu_read(xen_cr0_value); if (unlikely(cr0 == 0)) { cr0 = native_read_cr0(); this_cpu_write(xen_cr0_value, cr0); } return cr0; } static void xen_write_cr0(unsigned long cr0) { struct multicall_space mcs; this_cpu_write(xen_cr0_value, cr0); /* Only pay attention to cr0.TS; everything else is ignored. */ mcs = xen_mc_entry(0); MULTI_fpu_taskswitch(mcs.mc, (cr0 & X86_CR0_TS) != 0); xen_mc_issue(PARAVIRT_LAZY_CPU); } static void xen_write_cr4(unsigned long cr4) { cr4 &= ~(X86_CR4_PGE | X86_CR4_PSE | X86_CR4_PCE); native_write_cr4(cr4); } static u64 xen_read_msr_safe(unsigned int msr, int *err) { u64 val; if (pmu_msr_read(msr, &val, err)) return val; val = native_read_msr_safe(msr, err); switch (msr) { case MSR_IA32_APICBASE: val &= ~X2APIC_ENABLE; break; } return val; } static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high) { int ret; #ifdef CONFIG_X86_64 unsigned int which; u64 base; #endif ret = 0; switch (msr) { #ifdef CONFIG_X86_64 case MSR_FS_BASE: which = SEGBASE_FS; goto set; case MSR_KERNEL_GS_BASE: which = SEGBASE_GS_USER; goto set; case MSR_GS_BASE: which = SEGBASE_GS_KERNEL; goto set; set: base = ((u64)high << 32) | low; if (HYPERVISOR_set_segment_base(which, base) != 0) ret = -EIO; break; #endif case MSR_STAR: case MSR_CSTAR: case MSR_LSTAR: case MSR_SYSCALL_MASK: case MSR_IA32_SYSENTER_CS: case MSR_IA32_SYSENTER_ESP: case MSR_IA32_SYSENTER_EIP: /* Fast syscall setup is all done in hypercalls, so these are all ignored. Stub them out here to stop Xen console noise. */ break; default: if (!pmu_msr_write(msr, low, high, &ret)) ret = native_write_msr_safe(msr, low, high); } return ret; } static u64 xen_read_msr(unsigned int msr) { /* * This will silently swallow a #GP from RDMSR. It may be worth * changing that. */ int err; return xen_read_msr_safe(msr, &err); } static void xen_write_msr(unsigned int msr, unsigned low, unsigned high) { /* * This will silently swallow a #GP from WRMSR. It may be worth * changing that. */ xen_write_msr_safe(msr, low, high); } /* This is called once we have the cpu_possible_mask */ void __init xen_setup_vcpu_info_placement(void) { int cpu; for_each_possible_cpu(cpu) { /* Set up direct vCPU id mapping for PV guests. */ per_cpu(xen_vcpu_id, cpu) = cpu; /* * xen_vcpu_setup(cpu) can fail -- in which case it * falls back to the shared_info version for cpus * where xen_vcpu_nr(cpu) < MAX_VIRT_CPUS. * * xen_cpu_up_prepare_pv() handles the rest by failing * them in hotplug. */ (void) xen_vcpu_setup(cpu); } /* * xen_vcpu_setup managed to place the vcpu_info within the * percpu area for all cpus, so make use of it. */ if (xen_have_vcpu_info_placement) { pv_ops.irq.save_fl = __PV_IS_CALLEE_SAVE(xen_save_fl_direct); pv_ops.irq.restore_fl = __PV_IS_CALLEE_SAVE(xen_restore_fl_direct); pv_ops.irq.irq_disable = __PV_IS_CALLEE_SAVE(xen_irq_disable_direct); pv_ops.irq.irq_enable = __PV_IS_CALLEE_SAVE(xen_irq_enable_direct); pv_ops.mmu.read_cr2 = __PV_IS_CALLEE_SAVE(xen_read_cr2_direct); } } static const struct pv_info xen_info __initconst = { .shared_kernel_pmd = 0, #ifdef CONFIG_X86_64 .extra_user_64bit_cs = FLAT_USER_CS64, #endif .name = "Xen", }; static const struct pv_cpu_ops xen_cpu_ops __initconst = { .cpuid = xen_cpuid, .set_debugreg = xen_set_debugreg, .get_debugreg = xen_get_debugreg, .read_cr0 = xen_read_cr0, .write_cr0 = xen_write_cr0, .write_cr4 = xen_write_cr4, .wbinvd = native_wbinvd, .read_msr = xen_read_msr, .write_msr = xen_write_msr, .read_msr_safe = xen_read_msr_safe, .write_msr_safe = xen_write_msr_safe, .read_pmc = xen_read_pmc, .iret = xen_iret, #ifdef CONFIG_X86_64 .usergs_sysret64 = xen_sysret64, #endif .load_tr_desc = paravirt_nop, .set_ldt = xen_set_ldt, .load_gdt = xen_load_gdt, .load_idt = xen_load_idt, .load_tls = xen_load_tls, #ifdef CONFIG_X86_64 .load_gs_index = xen_load_gs_index, #endif .alloc_ldt = xen_alloc_ldt, .free_ldt = xen_free_ldt, .store_tr = xen_store_tr, .write_ldt_entry = xen_write_ldt_entry, .write_gdt_entry = xen_write_gdt_entry, .write_idt_entry = xen_write_idt_entry, .load_sp0 = xen_load_sp0, #ifdef CONFIG_X86_IOPL_IOPERM .update_io_bitmap = xen_update_io_bitmap, #endif .io_delay = xen_io_delay, /* Xen takes care of %gs when switching to usermode for us */ .swapgs = paravirt_nop, .start_context_switch = paravirt_start_context_switch, .end_context_switch = xen_end_context_switch, }; static void xen_restart(char *msg) { xen_reboot(SHUTDOWN_reboot); } static void xen_machine_halt(void) { xen_reboot(SHUTDOWN_poweroff); } static void xen_machine_power_off(void) { if (pm_power_off) pm_power_off(); xen_reboot(SHUTDOWN_poweroff); } static void xen_crash_shutdown(struct pt_regs *regs) { xen_reboot(SHUTDOWN_crash); } static const struct machine_ops xen_machine_ops __initconst = { .restart = xen_restart, .halt = xen_machine_halt, .power_off = xen_machine_power_off, .shutdown = xen_machine_halt, .crash_shutdown = xen_crash_shutdown, .emergency_restart = xen_emergency_restart, }; static unsigned char xen_get_nmi_reason(void) { unsigned char reason = 0; /* Construct a value which looks like it came from port 0x61. */ if (test_bit(_XEN_NMIREASON_io_error, &HYPERVISOR_shared_info->arch.nmi_reason)) reason |= NMI_REASON_IOCHK; if (test_bit(_XEN_NMIREASON_pci_serr, &HYPERVISOR_shared_info->arch.nmi_reason)) reason |= NMI_REASON_SERR; return reason; } static void __init xen_boot_params_init_edd(void) { #if IS_ENABLED(CONFIG_EDD) struct xen_platform_op op; struct edd_info *edd_info; u32 *mbr_signature; unsigned nr; int ret; edd_info = boot_params.eddbuf; mbr_signature = boot_params.edd_mbr_sig_buffer; op.cmd = XENPF_firmware_info; op.u.firmware_info.type = XEN_FW_DISK_INFO; for (nr = 0; nr < EDDMAXNR; nr++) { struct edd_info *info = edd_info + nr; op.u.firmware_info.index = nr; info->params.length = sizeof(info->params); set_xen_guest_handle(op.u.firmware_info.u.disk_info.edd_params, &info->params); ret = HYPERVISOR_platform_op(&op); if (ret) break; #define C(x) info->x = op.u.firmware_info.u.disk_info.x C(device); C(version); C(interface_support); C(legacy_max_cylinder); C(legacy_max_head); C(legacy_sectors_per_track); #undef C } boot_params.eddbuf_entries = nr; op.u.firmware_info.type = XEN_FW_DISK_MBR_SIGNATURE; for (nr = 0; nr < EDD_MBR_SIG_MAX; nr++) { op.u.firmware_info.index = nr; ret = HYPERVISOR_platform_op(&op); if (ret) break; mbr_signature[nr] = op.u.firmware_info.u.disk_mbr_signature.mbr_signature; } boot_params.edd_mbr_sig_buf_entries = nr; #endif } /* * Set up the GDT and segment registers for -fstack-protector. Until * we do this, we have to be careful not to call any stack-protected * function, which is most of the kernel. */ static void __init xen_setup_gdt(int cpu) { pv_ops.cpu.write_gdt_entry = xen_write_gdt_entry_boot; pv_ops.cpu.load_gdt = xen_load_gdt_boot; setup_stack_canary_segment(cpu); switch_to_new_gdt(cpu); pv_ops.cpu.write_gdt_entry = xen_write_gdt_entry; pv_ops.cpu.load_gdt = xen_load_gdt; } static void __init xen_dom0_set_legacy_features(void) { x86_platform.legacy.rtc = 1; } /* First C function to be called on Xen boot */ asmlinkage __visible void __init xen_start_kernel(void) { struct physdev_set_iopl set_iopl; unsigned long initrd_start = 0; int rc; if (!xen_start_info) return; xen_domain_type = XEN_PV_DOMAIN; xen_start_flags = xen_start_info->flags; xen_setup_features(); /* Install Xen paravirt ops */ pv_info = xen_info; pv_ops.init.patch = paravirt_patch_default; pv_ops.cpu = xen_cpu_ops; xen_init_irq_ops(); /* * Setup xen_vcpu early because it is needed for * local_irq_disable(), irqs_disabled(), e.g. in printk(). * * Don't do the full vcpu_info placement stuff until we have * the cpu_possible_mask and a non-dummy shared_info. */ xen_vcpu_info_reset(0); x86_platform.get_nmi_reason = xen_get_nmi_reason; x86_init.resources.memory_setup = xen_memory_setup; x86_init.irqs.intr_mode_select = x86_init_noop; x86_init.irqs.intr_mode_init = x86_init_noop; x86_init.oem.arch_setup = xen_arch_setup; x86_init.oem.banner = xen_banner; x86_init.hyper.init_platform = xen_pv_init_platform; x86_init.hyper.guest_late_init = xen_pv_guest_late_init; /* * Set up some pagetable state before starting to set any ptes. */ xen_setup_machphys_mapping(); xen_init_mmu_ops(); /* Prevent unwanted bits from being set in PTEs. */ __supported_pte_mask &= ~_PAGE_GLOBAL; __default_kernel_pte_mask &= ~_PAGE_GLOBAL; /* * Prevent page tables from being allocated in highmem, even * if CONFIG_HIGHPTE is enabled. */ __userpte_alloc_gfp &= ~__GFP_HIGHMEM; /* Get mfn list */ xen_build_dynamic_phys_to_machine(); /* * Set up kernel GDT and segment registers, mainly so that * -fstack-protector code can be executed. */ xen_setup_gdt(0); /* Work out if we support NX */ get_cpu_cap(&boot_cpu_data); x86_configure_nx(); /* Determine virtual and physical address sizes */ get_cpu_address_sizes(&boot_cpu_data); /* Let's presume PV guests always boot on vCPU with id 0. */ per_cpu(xen_vcpu_id, 0) = 0; idt_setup_early_handler(); xen_init_capabilities(); #ifdef CONFIG_X86_LOCAL_APIC /* * set up the basic apic ops. */ xen_init_apic(); #endif if (xen_feature(XENFEAT_mmu_pt_update_preserve_ad)) { pv_ops.mmu.ptep_modify_prot_start = xen_ptep_modify_prot_start; pv_ops.mmu.ptep_modify_prot_commit = xen_ptep_modify_prot_commit; } machine_ops = xen_machine_ops; /* * The only reliable way to retain the initial address of the * percpu gdt_page is to remember it here, so we can go and * mark it RW later, when the initial percpu area is freed. */ xen_initial_gdt = &per_cpu(gdt_page, 0); xen_smp_init(); #ifdef CONFIG_ACPI_NUMA /* * The pages we from Xen are not related to machine pages, so * any NUMA information the kernel tries to get from ACPI will * be meaningless. Prevent it from trying. */ acpi_numa = -1; #endif WARN_ON(xen_cpuhp_setup(xen_cpu_up_prepare_pv, xen_cpu_dead_pv)); local_irq_disable(); early_boot_irqs_disabled = true; xen_raw_console_write("mapping kernel into physical memory\n"); xen_setup_kernel_pagetable((pgd_t *)xen_start_info->pt_base, xen_start_info->nr_pages); xen_reserve_special_pages(); /* keep using Xen gdt for now; no urgent need to change it */ #ifdef CONFIG_X86_32 pv_info.kernel_rpl = 1; if (xen_feature(XENFEAT_supervisor_mode_kernel)) pv_info.kernel_rpl = 0; #else pv_info.kernel_rpl = 0; #endif /* set the limit of our address space */ xen_reserve_top(); /* * We used to do this in xen_arch_setup, but that is too late * on AMD were early_cpu_init (run before ->arch_setup()) calls * early_amd_init which pokes 0xcf8 port. */ set_iopl.iopl = 1; rc = HYPERVISOR_physdev_op(PHYSDEVOP_set_iopl, &set_iopl); if (rc != 0) xen_raw_printk("physdev_op failed %d\n", rc); #ifdef CONFIG_X86_32 /* set up basic CPUID stuff */ cpu_detect(&new_cpu_data); set_cpu_cap(&new_cpu_data, X86_FEATURE_FPU); new_cpu_data.x86_capability[CPUID_1_EDX] = cpuid_edx(1); #endif if (xen_start_info->mod_start) { if (xen_start_info->flags & SIF_MOD_START_PFN) initrd_start = PFN_PHYS(xen_start_info->mod_start); else initrd_start = __pa(xen_start_info->mod_start); } /* Poke various useful things into boot_params */ boot_params.hdr.type_of_loader = (9 << 4) | 0; boot_params.hdr.ramdisk_image = initrd_start; boot_params.hdr.ramdisk_size = xen_start_info->mod_len; boot_params.hdr.cmd_line_ptr = __pa(xen_start_info->cmd_line); boot_params.hdr.hardware_subarch = X86_SUBARCH_XEN; if (!xen_initial_domain()) { add_preferred_console("xenboot", 0, NULL); if (pci_xen) x86_init.pci.arch_init = pci_xen_init; } else { const struct dom0_vga_console_info *info = (void *)((char *)xen_start_info + xen_start_info->console.dom0.info_off); struct xen_platform_op op = { .cmd = XENPF_firmware_info, .interface_version = XENPF_INTERFACE_VERSION, .u.firmware_info.type = XEN_FW_KBD_SHIFT_FLAGS, }; x86_platform.set_legacy_features = xen_dom0_set_legacy_features; xen_init_vga(info, xen_start_info->console.dom0.info_size); xen_start_info->console.domU.mfn = 0; xen_start_info->console.domU.evtchn = 0; if (HYPERVISOR_platform_op(&op) == 0) boot_params.kbd_status = op.u.firmware_info.u.kbd_shift_flags; /* Make sure ACS will be enabled */ pci_request_acs(); xen_acpi_sleep_register(); /* Avoid searching for BIOS MP tables */ x86_init.mpparse.find_smp_config = x86_init_noop; x86_init.mpparse.get_smp_config = x86_init_uint_noop; xen_boot_params_init_edd(); } if (!boot_params.screen_info.orig_video_isVGA) add_preferred_console("tty", 0, NULL); add_preferred_console("hvc", 0, NULL); if (boot_params.screen_info.orig_video_isVGA) add_preferred_console("tty", 0, NULL); #ifdef CONFIG_PCI /* PCI BIOS service won't work from a PV guest. */ pci_probe &= ~PCI_PROBE_BIOS; #endif xen_raw_console_write("about to get started...\n"); /* We need this for printk timestamps */ xen_setup_runstate_info(0); xen_efi_init(&boot_params); /* Start the world */ #ifdef CONFIG_X86_32 i386_start_kernel(); #else cr4_init_shadow(); /* 32b kernel does this in i386_start_kernel() */ x86_64_start_reservations((char *)__pa_symbol(&boot_params)); #endif } static int xen_cpu_up_prepare_pv(unsigned int cpu) { int rc; if (per_cpu(xen_vcpu, cpu) == NULL) return -ENODEV; xen_setup_timer(cpu); rc = xen_smp_intr_init(cpu); if (rc) { WARN(1, "xen_smp_intr_init() for CPU %d failed: %d\n", cpu, rc); return rc; } rc = xen_smp_intr_init_pv(cpu); if (rc) { WARN(1, "xen_smp_intr_init_pv() for CPU %d failed: %d\n", cpu, rc); return rc; } return 0; } static int xen_cpu_dead_pv(unsigned int cpu) { xen_smp_intr_free(cpu); xen_smp_intr_free_pv(cpu); xen_teardown_timer(cpu); return 0; } static uint32_t __init xen_platform_pv(void) { if (xen_pv_domain()) return xen_cpuid_base(); return 0; } const __initconst struct hypervisor_x86 x86_hyper_xen_pv = { .name = "Xen PV", .detect = xen_platform_pv, .type = X86_HYPER_XEN_PV, .runtime.pin_vcpu = xen_pin_vcpu, .ignore_nopv = true, };