#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>
#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>
* 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
*/
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
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())
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]);
}
/*
* 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)
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? */
.wbinvd = native_wbinvd,
.read_msr = native_read_msr_safe,
- .rdmsr_regs = native_rdmsr_safe_regs,
.write_msr = xen_write_msr_safe,
- .wrmsr_regs = native_wrmsr_safe_regs,
.read_tsc = native_read_tsc,
.read_pmc = native_read_pmc,
#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)
{
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;
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