diff options
Diffstat (limited to 'arch/x86/xen/enlighten_pv.c')
| -rw-r--r-- | arch/x86/xen/enlighten_pv.c | 1485 |
1 files changed, 1485 insertions, 0 deletions
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c new file mode 100644 index 000000000..9280e15de --- /dev/null +++ b/arch/x86/xen/enlighten_pv.c @@ -0,0 +1,1485 @@ +// 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 <jeremy@xensource.com>, XenSource Inc, 2007 + */ + +#include <linux/cpu.h> +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/smp.h> +#include <linux/preempt.h> +#include <linux/hardirq.h> +#include <linux/percpu.h> +#include <linux/delay.h> +#include <linux/start_kernel.h> +#include <linux/sched.h> +#include <linux/kprobes.h> +#include <linux/kstrtox.h> +#include <linux/memblock.h> +#include <linux/export.h> +#include <linux/mm.h> +#include <linux/page-flags.h> +#include <linux/pci.h> +#include <linux/gfp.h> +#include <linux/edd.h> +#include <linux/reboot.h> +#include <linux/virtio_anchor.h> + +#include <xen/xen.h> +#include <xen/events.h> +#include <xen/interface/xen.h> +#include <xen/interface/version.h> +#include <xen/interface/physdev.h> +#include <xen/interface/vcpu.h> +#include <xen/interface/memory.h> +#include <xen/interface/nmi.h> +#include <xen/interface/xen-mca.h> +#include <xen/features.h> +#include <xen/page.h> +#include <xen/hvc-console.h> +#include <xen/acpi.h> + +#include <asm/paravirt.h> +#include <asm/apic.h> +#include <asm/page.h> +#include <asm/xen/pci.h> +#include <asm/xen/hypercall.h> +#include <asm/xen/hypervisor.h> +#include <asm/xen/cpuid.h> +#include <asm/fixmap.h> +#include <asm/processor.h> +#include <asm/proto.h> +#include <asm/msr-index.h> +#include <asm/traps.h> +#include <asm/setup.h> +#include <asm/desc.h> +#include <asm/pgalloc.h> +#include <asm/tlbflush.h> +#include <asm/reboot.h> +#include <asm/stackprotector.h> +#include <asm/hypervisor.h> +#include <asm/mach_traps.h> +#include <asm/mwait.h> +#include <asm/pci_x86.h> +#include <asm/cpu.h> +#ifdef CONFIG_X86_IOPL_IOPERM +#include <asm/io_bitmap.h> +#endif + +#ifdef CONFIG_ACPI +#include <linux/acpi.h> +#include <asm/acpi.h> +#include <acpi/pdc_intel.h> +#include <acpi/processor.h> +#include <xen/interface/platform.h> +#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 __read_mostly bool xen_msr_safe = IS_ENABLED(CONFIG_XEN_PV_MSR_SAFE); + +static int __init parse_xen_msr_safe(char *str) +{ + if (str) + return kstrtobool(str, &xen_msr_safe); + return -EINVAL; +} +early_param("xen_msr_safe", parse_xen_msr_safe); + +static void __init xen_pv_init_platform(void) +{ + /* PV guests can't operate virtio devices without grants. */ + if (IS_ENABLED(CONFIG_XEN_VIRTIO)) + virtio_set_mem_acc_cb(xen_virtio_restricted_mem_acc); + + 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 +} + +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; +} + +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 noinstr void xen_set_debugreg(int reg, unsigned long val) +{ + HYPERVISOR_set_debugreg(reg, val); +} + +static noinstr 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; + unsigned char dummy; + void *va; + + ptep = lookup_address((unsigned long)v, &level); + BUG_ON(ptep == NULL); + + pfn = pte_pfn(*ptep); + 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(); + + copy_from_kernel_nofault(&dummy, v, 1); + + if (HYPERVISOR_update_va_mapping((unsigned long)v, pte, 0)) + BUG(); + + va = __va(PFN_PHYS(pfn)); + + if (va != v && HYPERVISOR_update_va_mapping((unsigned long)va, pte, 0)) + BUG(); + + 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) +{ + /* + * In lazy mode 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) + loadsegment(fs, 0); + + 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); +} + +static void xen_load_gs_index(unsigned int idx) +{ + if (HYPERVISOR_set_segment_base(SEGBASE_GS_USER_SEL, idx)) + BUG(); +} + +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(); +} + +void noist_exc_debug(struct pt_regs *regs); + +DEFINE_IDTENTRY_RAW(xenpv_exc_nmi) +{ + /* On Xen PV, NMI doesn't use IST. The C part is the same as native. */ + exc_nmi(regs); +} + +DEFINE_IDTENTRY_RAW_ERRORCODE(xenpv_exc_double_fault) +{ + /* On Xen PV, DF doesn't use IST. The C part is the same as native. */ + exc_double_fault(regs, error_code); +} + +DEFINE_IDTENTRY_RAW(xenpv_exc_debug) +{ + /* + * There's no IST on Xen PV, but we still need to dispatch + * to the correct handler. + */ + if (user_mode(regs)) + noist_exc_debug(regs); + else + exc_debug(regs); +} + +DEFINE_IDTENTRY_RAW(exc_xen_unknown_trap) +{ + /* This should never happen and there is no way to handle it. */ + instrumentation_begin(); + pr_err("Unknown trap in Xen PV mode."); + BUG(); + instrumentation_end(); +} + +#ifdef CONFIG_X86_MCE +DEFINE_IDTENTRY_RAW(xenpv_exc_machine_check) +{ + /* + * There's no IST on Xen PV, but we still need to dispatch + * to the correct handler. + */ + if (user_mode(regs)) + noist_exc_machine_check(regs); + else + exc_machine_check(regs); +} +#endif + +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 } + +#define TRAP_ENTRY_REDIR(func, ist_ok) { \ + .orig = asm_##func, \ + .xen = xen_asm_xenpv_##func, \ + .ist_okay = ist_ok } + +static struct trap_array_entry trap_array[] = { + TRAP_ENTRY_REDIR(exc_debug, true ), + TRAP_ENTRY_REDIR(exc_double_fault, true ), +#ifdef CONFIG_X86_MCE + TRAP_ENTRY_REDIR(exc_machine_check, true ), +#endif + TRAP_ENTRY_REDIR(exc_nmi, true ), + TRAP_ENTRY(exc_int3, false ), + TRAP_ENTRY(exc_overflow, false ), +#ifdef CONFIG_IA32_EMULATION + TRAP_ENTRY(int80_emulation, false ), +#endif + TRAP_ENTRY(exc_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 ), + TRAP_ENTRY(exc_coprocessor_error, false ), + TRAP_ENTRY(exc_alignment_check, false ), + TRAP_ENTRY(exc_simd_coprocessor_error, false ), +#ifdef CONFIG_X86_KERNEL_IBT + TRAP_ENTRY(exc_control_protection, false ), +#endif +}; + +static bool __ref get_trap_addr(void **addr, unsigned int ist) +{ + unsigned int nr; + bool ist_okay = false; + bool found = 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; + found = true; + 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]; + found = true; + } + + if (!found) + *addr = (void *)xen_asm_exc_xen_unknown_trap; + + if (WARN_ON(found && ist != 0 && !ist_okay)) + return false; + + return true; +} + +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); + if (!get_trap_addr((void **)&addr, val->bits.ist)) + return 0; + 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 unsigned xen_convert_trap_info(const struct desc_ptr *desc, + struct trap_info *traps, bool full) +{ + 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]) || full) + out++; + } + + return out; +} + +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, true); +} + +/* 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]; + static const struct trap_info zero = { }; + unsigned out; + + trace_xen_cpu_load_idt(desc); + + spin_lock(&lock); + + memcpy(this_cpu_ptr(&idt_desc), desc, sizeof(idt_desc)); + + out = xen_convert_trap_info(desc, traps, false); + traps[out] = zero; + + 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_invalidate_io_bitmap(void) +{ + struct physdev_set_iobitmap iobitmap = { + .bitmap = NULL, + .nr_ports = 0, + }; + + native_tss_invalidate_io_bitmap(); + HYPERVISOR_physdev_op(PHYSDEVOP_set_iobitmap, &iobitmap); +} + +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_do_read_msr(unsigned int msr, int *err) +{ + u64 val = 0; /* Avoid uninitialized value for safe variant. */ + + if (pmu_msr_read(msr, &val, err)) + return val; + + if (err) + val = native_read_msr_safe(msr, err); + else + val = native_read_msr(msr); + + switch (msr) { + case MSR_IA32_APICBASE: + val &= ~X2APIC_ENABLE; + break; + } + return val; +} + +static void set_seg(unsigned int which, unsigned int low, unsigned int high, + int *err) +{ + u64 base = ((u64)high << 32) | low; + + if (HYPERVISOR_set_segment_base(which, base) == 0) + return; + + if (err) + *err = -EIO; + else + WARN(1, "Xen set_segment_base(%u, %llx) failed\n", which, base); +} + +/* + * Support write_msr_safe() and write_msr() semantics. + * With err == NULL write_msr() semantics are selected. + * Supplying an err pointer requires err to be pre-initialized with 0. + */ +static void xen_do_write_msr(unsigned int msr, unsigned int low, + unsigned int high, int *err) +{ + switch (msr) { + case MSR_FS_BASE: + set_seg(SEGBASE_FS, low, high, err); + break; + + case MSR_KERNEL_GS_BASE: + set_seg(SEGBASE_GS_USER, low, high, err); + break; + + case MSR_GS_BASE: + set_seg(SEGBASE_GS_KERNEL, low, high, err); + break; + + 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, err)) { + if (err) + *err = native_write_msr_safe(msr, low, high); + else + native_write_msr(msr, low, high); + } + } +} + +static u64 xen_read_msr_safe(unsigned int msr, int *err) +{ + return xen_do_read_msr(msr, err); +} + +static int xen_write_msr_safe(unsigned int msr, unsigned int low, + unsigned int high) +{ + int err = 0; + + xen_do_write_msr(msr, low, high, &err); + + return err; +} + +static u64 xen_read_msr(unsigned int msr) +{ + int err; + + return xen_do_read_msr(msr, xen_msr_safe ? &err : NULL); +} + +static void xen_write_msr(unsigned int msr, unsigned low, unsigned high) +{ + int err; + + xen_do_write_msr(msr, low, high, xen_msr_safe ? &err : NULL); +} + +/* 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); + } + + pv_ops.irq.save_fl = __PV_IS_CALLEE_SAVE(xen_save_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 = { + .extra_user_64bit_cs = FLAT_USER_CS64, + .name = "Xen", +}; + +static const typeof(pv_ops) xen_cpu_ops __initconst = { + .cpu = { + .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, + + .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, + .load_gs_index = xen_load_gs_index, + + .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 + .invalidate_io_bitmap = xen_invalidate_io_bitmap, + .update_io_bitmap = xen_update_io_bitmap, +#endif + .io_delay = xen_io_delay, + + .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) +{ + do_kernel_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; + + 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; +} + +static void __init xen_domu_set_legacy_features(void) +{ + x86_platform.legacy.rtc = 0; +} + +extern void early_xen_iret_patch(void); + +/* First C function to be called on Xen boot */ +asmlinkage __visible void __init xen_start_kernel(struct start_info *si) +{ + struct physdev_set_iopl set_iopl; + unsigned long initrd_start = 0; + int rc; + + if (!si) + return; + + clear_bss(); + + xen_start_info = si; + + __text_gen_insn(&early_xen_iret_patch, + JMP32_INSN_OPCODE, &early_xen_iret_patch, &xen_iret, + JMP32_INSN_SIZE); + + 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.cpu = xen_cpu_ops.cpu; + 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_platform.realmode_reserve = x86_init_noop; + x86_platform.realmode_init = x86_init_noop; + + 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; + + /* Get mfn list */ + xen_build_dynamic_phys_to_machine(); + + /* Work out if we support NX */ + get_cpu_cap(&boot_cpu_data); + x86_configure_nx(); + + /* + * Set up kernel GDT and segment registers, mainly so that + * -fstack-protector code can be executed. + */ + xen_setup_gdt(0); + + /* 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 + + 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. + */ + disable_srat(); +#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(); + + /* + * 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); + + + 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()) { + if (pci_xen) + x86_init.pci.arch_init = pci_xen_init; + x86_platform.set_legacy_features = + xen_domu_set_legacy_features; + } 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, + &boot_params.screen_info); + 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(); + + xen_boot_params_init_edd(); + +#ifdef CONFIG_ACPI + /* + * Disable selecting "Firmware First mode" for correctable + * memory errors, as this is the duty of the hypervisor to + * decide. + */ + acpi_disable_cmcff = 1; +#endif + } + + xen_add_preferred_consoles(); + +#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 */ + cr4_init_shadow(); /* 32b kernel does this in i386_start_kernel() */ + x86_64_start_reservations((char *)__pa_symbol(&boot_params)); +} + +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, +}; |