diff options
Diffstat (limited to 'arch/x86/xen/enlighten.c')
| -rw-r--r-- | arch/x86/xen/enlighten.c | 224 |
1 files changed, 173 insertions, 51 deletions
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index ed7d54985d0c..bf4bda6d3e9a 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -31,6 +31,7 @@ #include <linux/pci.h> #include <linux/gfp.h> #include <linux/memblock.h> +#include <linux/syscore_ops.h> #include <xen/xen.h> #include <xen/interface/xen.h> @@ -38,6 +39,7 @@ #include <xen/interface/physdev.h> #include <xen/interface/vcpu.h> #include <xen/interface/memory.h> +#include <xen/interface/xen-mca.h> #include <xen/features.h> #include <xen/page.h> #include <xen/hvm.h> @@ -107,7 +109,7 @@ EXPORT_SYMBOL_GPL(xen_have_vector_callback); * Point at some empty memory to start with. We map the real shared_info * page as soon as fixmap is up and running. */ -struct shared_info *HYPERVISOR_shared_info = (void *)&xen_dummy_shared_info; +struct shared_info *HYPERVISOR_shared_info = &xen_dummy_shared_info; /* * Flag to determine whether vcpu info placement is available on all @@ -124,6 +126,19 @@ struct shared_info *HYPERVISOR_shared_info = (void *)&xen_dummy_shared_info; */ static int have_vcpu_info_placement = 1; +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 clamp_max_cpus(void) { #ifdef CONFIG_SMP @@ -341,9 +356,7 @@ static void __init xen_init_cpuid_mask(void) unsigned int xsave_mask; cpuid_leaf1_edx_mask = - ~((1 << X86_FEATURE_MCE) | /* disable MCE */ - (1 << X86_FEATURE_MCA) | /* disable MCA */ - (1 << X86_FEATURE_MTRR) | /* disable MTRR */ + ~((1 << X86_FEATURE_MTRR) | /* disable MTRR */ (1 << X86_FEATURE_ACC)); /* thermal monitoring */ if (!xen_initial_domain()) @@ -540,12 +553,28 @@ static void __init xen_load_gdt_boot(const struct desc_ptr *dtr) BUG(); } +static inline bool desc_equal(const struct desc_struct *d1, + const struct desc_struct *d2) +{ + return d1->a == d2->a && d1->b == d2->b; +} + static void load_TLS_descriptor(struct thread_struct *t, unsigned int cpu, unsigned int i) { - struct desc_struct *gdt = get_cpu_gdt_table(cpu); - xmaddr_t maddr = arbitrary_virt_to_machine(&gdt[GDT_ENTRY_TLS_MIN+i]); - struct multicall_space mc = __xen_mc_entry(0); + 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_table(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]); } @@ -627,8 +656,8 @@ static int cvt_gate_to_trap(int vector, const gate_desc *val, /* * Look for known traps using IST, and substitute them * appropriately. The debugger ones are the only ones we care - * about. Xen will handle faults like double_fault and - * machine_check, so we should never see them. Warn if + * about. Xen will handle faults like double_fault, + * so we should never see them. Warn if * there's an unexpected IST-using fault handler. */ if (addr == (unsigned long)debug) @@ -643,7 +672,11 @@ static int cvt_gate_to_trap(int vector, const gate_desc *val, return 0; #ifdef CONFIG_X86_MCE } else if (addr == (unsigned long)machine_check) { - return 0; + /* + * when xen hypervisor inject vMCE to guest, + * use native mce handler to handle it + */ + ; #endif } else { /* Some other trap using IST? */ @@ -1437,64 +1470,155 @@ asmlinkage void __init xen_start_kernel(void) #endif } -static int init_hvm_pv_info(int *major, int *minor) -{ - uint32_t eax, ebx, ecx, edx, pages, msr, base; - u64 pfn; - - base = xen_cpuid_base(); - cpuid(base + 1, &eax, &ebx, &ecx, &edx); - - *major = eax >> 16; - *minor = eax & 0xffff; - printk(KERN_INFO "Xen version %d.%d.\n", *major, *minor); - - cpuid(base + 2, &pages, &msr, &ecx, &edx); - - pfn = __pa(hypercall_page); - wrmsr_safe(msr, (u32)pfn, (u32)(pfn >> 32)); - - xen_setup_features(); - - pv_info.name = "Xen HVM"; - - xen_domain_type = XEN_HVM_DOMAIN; +#ifdef CONFIG_XEN_PVHVM +/* + * The pfn containing the shared_info is located somewhere in RAM. This + * will cause trouble if the current kernel is doing a kexec boot into a + * new kernel. The new kernel (and its startup code) can not know where + * the pfn is, so it can not reserve the page. The hypervisor will + * continue to update the pfn, and as a result memory corruption occours + * in the new kernel. + * + * One way to work around this issue is to allocate a page in the + * xen-platform pci device's BAR memory range. But pci init is done very + * late and the shared_info page is already in use very early to read + * the pvclock. So moving the pfn from RAM to MMIO is racy because some + * code paths on other vcpus could access the pfn during the small + * window when the old pfn is moved to the new pfn. There is even a + * small window were the old pfn is not backed by a mfn, and during that + * time all reads return -1. + * + * Because it is not known upfront where the MMIO region is located it + * can not be used right from the start in xen_hvm_init_shared_info. + * + * To minimise trouble the move of the pfn is done shortly before kexec. + * This does not eliminate the race because all vcpus are still online + * when the syscore_ops will be called. But hopefully there is no work + * pending at this point in time. Also the syscore_op is run last which + * reduces the risk further. + */ - return 0; -} +static struct shared_info *xen_hvm_shared_info; -void __ref xen_hvm_init_shared_info(void) +static void xen_hvm_connect_shared_info(unsigned long pfn) { - int cpu; struct xen_add_to_physmap xatp; - static struct shared_info *shared_info_page = 0; - if (!shared_info_page) - shared_info_page = (struct shared_info *) - extend_brk(PAGE_SIZE, PAGE_SIZE); xatp.domid = DOMID_SELF; xatp.idx = 0; xatp.space = XENMAPSPACE_shared_info; - xatp.gpfn = __pa(shared_info_page) >> PAGE_SHIFT; + xatp.gpfn = pfn; if (HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp)) BUG(); - HYPERVISOR_shared_info = (struct shared_info *)shared_info_page; +} +static void xen_hvm_set_shared_info(struct shared_info *sip) +{ + int cpu; + + HYPERVISOR_shared_info = sip; /* xen_vcpu is a pointer to the vcpu_info struct in the shared_info * page, we use it in the event channel upcall and in some pvclock * related functions. We don't need the vcpu_info placement * optimizations because we don't use any pv_mmu or pv_irq op on * HVM. - * When xen_hvm_init_shared_info is run at boot time only vcpu 0 is - * online but xen_hvm_init_shared_info is run at resume time too and + * When xen_hvm_set_shared_info is run at boot time only vcpu 0 is + * online but xen_hvm_set_shared_info is run at resume time too and * in that case multiple vcpus might be online. */ for_each_online_cpu(cpu) { per_cpu(xen_vcpu, cpu) = &HYPERVISOR_shared_info->vcpu_info[cpu]; } } -#ifdef CONFIG_XEN_PVHVM +/* Reconnect the shared_info pfn to a mfn */ +void xen_hvm_resume_shared_info(void) +{ + xen_hvm_connect_shared_info(__pa(xen_hvm_shared_info) >> PAGE_SHIFT); +} + +#ifdef CONFIG_KEXEC +static struct shared_info *xen_hvm_shared_info_kexec; +static unsigned long xen_hvm_shared_info_pfn_kexec; + +/* Remember a pfn in MMIO space for kexec reboot */ +void __devinit xen_hvm_prepare_kexec(struct shared_info *sip, unsigned long pfn) +{ + xen_hvm_shared_info_kexec = sip; + xen_hvm_shared_info_pfn_kexec = pfn; +} + +static void xen_hvm_syscore_shutdown(void) +{ + struct xen_memory_reservation reservation = { + .domid = DOMID_SELF, + .nr_extents = 1, + }; + unsigned long prev_pfn; + int rc; + + if (!xen_hvm_shared_info_kexec) + return; + + prev_pfn = __pa(xen_hvm_shared_info) >> PAGE_SHIFT; + set_xen_guest_handle(reservation.extent_start, &prev_pfn); + + /* Move pfn to MMIO, disconnects previous pfn from mfn */ + xen_hvm_connect_shared_info(xen_hvm_shared_info_pfn_kexec); + + /* Update pointers, following hypercall is also a memory barrier */ + xen_hvm_set_shared_info(xen_hvm_shared_info_kexec); + + /* Allocate new mfn for previous pfn */ + do { + rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation); + if (rc == 0) + msleep(123); + } while (rc == 0); + + /* Make sure the previous pfn is really connected to a (new) mfn */ + BUG_ON(rc != 1); +} + +static struct syscore_ops xen_hvm_syscore_ops = { + .shutdown = xen_hvm_syscore_shutdown, +}; +#endif + +/* Use a pfn in RAM, may move to MMIO before kexec. */ +static void __init xen_hvm_init_shared_info(void) +{ + /* Remember pointer for resume */ + xen_hvm_shared_info = extend_brk(PAGE_SIZE, PAGE_SIZE); + xen_hvm_connect_shared_info(__pa(xen_hvm_shared_info) >> PAGE_SHIFT); + xen_hvm_set_shared_info(xen_hvm_shared_info); +} + +static void __init init_hvm_pv_info(void) +{ + int major, minor; + uint32_t eax, ebx, ecx, edx, pages, msr, base; + u64 pfn; + + base = xen_cpuid_base(); + cpuid(base + 1, &eax, &ebx, &ecx, &edx); + + major = eax >> 16; + minor = eax & 0xffff; + printk(KERN_INFO "Xen version %d.%d.\n", major, minor); + + cpuid(base + 2, &pages, &msr, &ecx, &edx); + + pfn = __pa(hypercall_page); + wrmsr_safe(msr, (u32)pfn, (u32)(pfn >> 32)); + + xen_setup_features(); + + pv_info.name = "Xen HVM"; + + xen_domain_type = XEN_HVM_DOMAIN; +} + static int __cpuinit xen_hvm_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) { @@ -1517,14 +1641,12 @@ static struct notifier_block xen_hvm_cpu_notifier __cpuinitdata = { static void __init xen_hvm_guest_init(void) { - int r; - int major, minor; - - r = init_hvm_pv_info(&major, &minor); - if (r < 0) - return; + init_hvm_pv_info(); xen_hvm_init_shared_info(); +#ifdef CONFIG_KEXEC + register_syscore_ops(&xen_hvm_syscore_ops); +#endif if (xen_feature(XENFEAT_hvm_callback_vector)) xen_have_vector_callback = 1; |