kvmfornfv -

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author	Liang Li <liang.z.li@intel.com>	2015-12-08 09:14:07 +0800
committer	Liang Li <liang.z.li@intel.com>	2015-12-08 09:16:17 +0800
commit	b52baab237a0b45cb18b26f529e6490b42574209 (patch)
tree	e8bd69d1ccf45f46381617d27cfdd1966abde0b1 /kernel/Documentation/hwmon/powr1220
parent	cc62f651747d5844cc12d33fb3620a7d05bae7dc (diff)

kvmclock: add a new function to update env->tsc.WW-2015-52

(Back port from upstream, commit id: 0fd7e098db30e302d27920487f0afec) The commit 317b0a6d8 fixed an issue which caused by the outdated env->tsc value, but the fix lead to 'cpu_synchronize_all_states()' called twice during live migration. The 'cpu_synchronize_all_states()' takes about 130us for a VM which has 4 vcpus, it's a bit expensive. Synchronize the whole CPU context just for updating env->tsc is too wasting, this patch use a new function to update the env->tsc. Comparing to 'cpu_synchronize_all_states()', it only takes about 20us. Change-Id: I7dc8371aa17b005d073249c3732d9a7424f20a25 Signed-off-by: Liang Li <liang.z.li@intel.com> Message-Id: <1446695464-27116-2-git-send-email-liang.z.li@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Diffstat (limited to 'kernel/Documentation/hwmon/powr1220')

0 files changed, 0 insertions, 0 deletions

/* * This file is subject to the terms and conditions of the GNU General Public * License. See the file "COPYING" in the main directory of this archive * for more details. * * Copyright (C) 1995 - 2000 by Ralf Baechle */ #include <linux/context_tracking.h> #include <linux/signal.h> #include <linux/sched.h> #include <linux/interrupt.h> #include <linux/kernel.h> #include <linux/errno.h> #include <linux/string.h> #include <linux/types.h> #include <linux/ptrace.h> #include <linux/ratelimit.h> #include <linux/mman.h> #include <linux/mm.h> #include <linux/smp.h> #include <linux/module.h> #include <linux/kprobes.h> #include <linux/perf_event.h> #include <linux/uaccess.h> #include <asm/branch.h> #include <asm/mmu_context.h> #include <asm/ptrace.h> #include <asm/highmem.h> /* For VMALLOC_END */ #include <linux/kdebug.h> int show_unhandled_signals = 1; /* * This routine handles page faults. It determines the address, * and the problem, and then passes it off to one of the appropriate * routines. */ static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write, unsigned long address) { struct vm_area_struct * vma = NULL; struct task_struct *tsk = current; struct mm_struct *mm = tsk->mm; const int field = sizeof(unsigned long) * 2; siginfo_t info; int fault; unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10); #if 0 printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(), current->comm, current->pid, field, address, write, field, regs->cp0_epc); #endif #ifdef CONFIG_KPROBES /* * This is to notify the fault handler of the kprobes. The * exception code is redundant as it is also carried in REGS, * but we pass it anyhow. */ if (notify_die(DIE_PAGE_FAULT, "page fault", regs, -1, (regs->cp0_cause >> 2) & 0x1f, SIGSEGV) == NOTIFY_STOP) return; #endif info.si_code = SEGV_MAPERR; /* * We fault-in kernel-space virtual memory on-demand. The * 'reference' page table is init_mm.pgd. * * NOTE! We MUST NOT take any locks for this case. We may * be in an interrupt or a critical region, and should * only copy the information from the master page table, * nothing more. */ #ifdef CONFIG_64BIT # define VMALLOC_FAULT_TARGET no_context #else # define VMALLOC_FAULT_TARGET vmalloc_fault #endif if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END)) goto VMALLOC_FAULT_TARGET; #ifdef MODULE_START if (unlikely(address >= MODULE_START && address < MODULE_END)) goto VMALLOC_FAULT_TARGET; #endif /* * If we're in an interrupt or have no user * context, we must not take the fault.. */ if (faulthandler_disabled() || !mm) goto bad_area_nosemaphore; if (user_mode(regs)) flags |= FAULT_FLAG_USER; retry: down_read(&mm->mmap_sem); vma = find_vma(mm, address); if (!vma) goto bad_area; if (vma->vm_start <= address) goto good_area; if (!(vma->vm_flags & VM_GROWSDOWN)) goto bad_area; if (expand_stack(vma, address)) goto bad_area; /* * Ok, we have a good vm_area for this memory access, so * we can handle it.. */ good_area: info.si_code = SEGV_ACCERR; if (write) { if (!(vma->vm_flags & VM_WRITE)) goto bad_area; flags |= FAULT_FLAG_WRITE; } else { if (cpu_has_rixi) { if (address == regs->cp0_epc && !(vma->vm_flags & VM_EXEC)) { #if 0 pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] XI violation\n", raw_smp_processor_id(), current->comm, current->pid, field, address, write, field, regs->cp0_epc); #endif goto bad_area; } if (!(vma->vm_flags & VM_READ)) { #if 0 pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] RI violation\n", raw_smp_processor_id(), current->comm, current->pid, field, address, write, field, regs->cp0_epc); #endif goto bad_area; } } else { if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))) goto bad_area; } } /* * If for any reason at all we couldn't handle the fault, * make sure we exit gracefully rather than endlessly redo * the fault. */ fault = handle_mm_fault(mm, vma, address, flags); if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) return; perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); if (unlikely(fault & VM_FAULT_ERROR)) { if (fault & VM_FAULT_OOM) goto out_of_memory; else if (fault & VM_FAULT_SIGSEGV) goto bad_area; else if (fault & VM_FAULT_SIGBUS) goto do_sigbus; BUG(); } if (flags & FAULT_FLAG_ALLOW_RETRY) { if (fault & VM_FAULT_MAJOR) { perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address); tsk->maj_flt++; } else { perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address); tsk->min_flt++; } if (fault & VM_FAULT_RETRY) { flags &= ~FAULT_FLAG_ALLOW_RETRY; flags |= FAULT_FLAG_TRIED; /* * No need to up_read(&mm->mmap_sem) as we would * have already released it in __lock_page_or_retry * in mm/filemap.c. */ goto retry; } } up_read(&mm->mmap_sem); return; /* * Something tried to access memory that isn't in our memory map.. * Fix it, but check if it's kernel or user first.. */ bad_area: up_read(&mm->mmap_sem); bad_area_nosemaphore: /* User mode accesses just cause a SIGSEGV */ if (user_mode(regs)) { tsk->thread.cp0_badvaddr = address; tsk->thread.error_code = write; if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) && __ratelimit(&ratelimit_state)) { pr_info("\ndo_page_fault(): sending SIGSEGV to %s for invalid %s %0*lx", tsk->comm, write ? "write access to" : "read access from", field, address); pr_info("epc = %0*lx in", field, (unsigned long) regs->cp0_epc); print_vma_addr(" ", regs->cp0_epc); pr_info("ra = %0*lx in", field, (unsigned long) regs->regs[31]); print_vma_addr(" ", regs->regs[31]); pr_info("\n"); } info.si_signo = SIGSEGV; info.si_errno = 0; /* info.si_code has been set above */ info.si_addr = (void __user *) address; force_sig_info(SIGSEGV, &info, tsk); return; } no_context: /* Are we prepared to handle this kernel fault? */ if (fixup_exception(regs)) { current->thread.cp0_baduaddr = address; return; } /* * Oops. The kernel tried to access some bad page. We'll have to * terminate things with extreme prejudice. */ bust_spinlocks(1); printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at " "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n", raw_smp_processor_id(), field, address, field, regs->cp0_epc, field, regs->regs[31]); die("Oops", regs); out_of_memory: /* * We ran out of memory, call the OOM killer, and return the userspace * (which will retry the fault, or kill us if we got oom-killed). */ up_read(&mm->mmap_sem); if (!user_mode(regs)) goto no_context; pagefault_out_of_memory(); return; do_sigbus: up_read(&mm->mmap_sem); /* Kernel mode? Handle exceptions or die */ if (!user_mode(regs)) goto no_context; else /* * Send a sigbus, regardless of whether we were in kernel * or user mode. */ #if 0 printk("do_page_fault() #3: sending SIGBUS to %s for " "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n", tsk->comm, write ? "write access to" : "read access from", field, address, field, (unsigned long) regs->cp0_epc, field, (unsigned long) regs->regs[31]); #endif tsk->thread.cp0_badvaddr = address; info.si_signo = SIGBUS; info.si_errno = 0; info.si_code = BUS_ADRERR; info.si_addr = (void __user *) address; force_sig_info(SIGBUS, &info, tsk); return; #ifndef CONFIG_64BIT vmalloc_fault: { /* * Synchronize this task's top level page-table * with the 'reference' page table. * * Do _not_ use "tsk" here. We might be inside * an interrupt in the middle of a task switch.. */ int offset = __pgd_offset(address); pgd_t *pgd, *pgd_k; pud_t *pud, *pud_k; pmd_t *pmd, *pmd_k; pte_t *pte_k; pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + offset; pgd_k = init_mm.pgd + offset; if (!pgd_present(*pgd_k)) goto no_context; set_pgd(pgd, *pgd_k); pud = pud_offset(pgd, address); pud_k = pud_offset(pgd_k, address); if (!pud_present(*pud_k)) goto no_context; pmd = pmd_offset(pud, address); pmd_k = pmd_offset(pud_k, address); if (!pmd_present(*pmd_k)) goto no_context; set_pmd(pmd, *pmd_k); pte_k = pte_offset_kernel(pmd_k, address); if (!pte_present(*pte_k)) goto no_context; return; } #endif } asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, unsigned long write, unsigned long address) { enum ctx_state prev_state; prev_state = exception_enter(); __do_page_fault(regs, write, address); exception_exit(prev_state); }


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