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@ -31,7 +31,6 @@
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#include <linux/pci.h>
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#include <linux/gfp.h>
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#include <linux/memblock.h>
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#include <linux/syscore_ops.h>
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#include <xen/xen.h>
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#include <xen/interface/xen.h>
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@ -1472,130 +1471,38 @@ asmlinkage void __init xen_start_kernel(void)
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#endif
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}
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#ifdef CONFIG_XEN_PVHVM
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/*
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* The pfn containing the shared_info is located somewhere in RAM. This
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* will cause trouble if the current kernel is doing a kexec boot into a
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* new kernel. The new kernel (and its startup code) can not know where
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* the pfn is, so it can not reserve the page. The hypervisor will
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* continue to update the pfn, and as a result memory corruption occours
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* in the new kernel.
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*
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* One way to work around this issue is to allocate a page in the
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* xen-platform pci device's BAR memory range. But pci init is done very
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* late and the shared_info page is already in use very early to read
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* the pvclock. So moving the pfn from RAM to MMIO is racy because some
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* code paths on other vcpus could access the pfn during the small
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* window when the old pfn is moved to the new pfn. There is even a
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* small window were the old pfn is not backed by a mfn, and during that
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* time all reads return -1.
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*
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* Because it is not known upfront where the MMIO region is located it
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* can not be used right from the start in xen_hvm_init_shared_info.
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*
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* To minimise trouble the move of the pfn is done shortly before kexec.
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* This does not eliminate the race because all vcpus are still online
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* when the syscore_ops will be called. But hopefully there is no work
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* pending at this point in time. Also the syscore_op is run last which
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* reduces the risk further.
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*/
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static struct shared_info *xen_hvm_shared_info;
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static void xen_hvm_connect_shared_info(unsigned long pfn)
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void __ref xen_hvm_init_shared_info(void)
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{
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int cpu;
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struct xen_add_to_physmap xatp;
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static struct shared_info *shared_info_page = 0;
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if (!shared_info_page)
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shared_info_page = (struct shared_info *)
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extend_brk(PAGE_SIZE, PAGE_SIZE);
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xatp.domid = DOMID_SELF;
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xatp.idx = 0;
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xatp.space = XENMAPSPACE_shared_info;
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xatp.gpfn = pfn;
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xatp.gpfn = __pa(shared_info_page) >> PAGE_SHIFT;
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if (HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp))
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BUG();
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}
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static void xen_hvm_set_shared_info(struct shared_info *sip)
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{
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int cpu;
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HYPERVISOR_shared_info = sip;
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HYPERVISOR_shared_info = (struct shared_info *)shared_info_page;
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/* xen_vcpu is a pointer to the vcpu_info struct in the shared_info
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* page, we use it in the event channel upcall and in some pvclock
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* related functions. We don't need the vcpu_info placement
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* optimizations because we don't use any pv_mmu or pv_irq op on
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* HVM.
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* When xen_hvm_set_shared_info is run at boot time only vcpu 0 is
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* online but xen_hvm_set_shared_info is run at resume time too and
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* When xen_hvm_init_shared_info is run at boot time only vcpu 0 is
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* online but xen_hvm_init_shared_info is run at resume time too and
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* in that case multiple vcpus might be online. */
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for_each_online_cpu(cpu) {
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per_cpu(xen_vcpu, cpu) = &HYPERVISOR_shared_info->vcpu_info[cpu];
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}
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}
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/* Reconnect the shared_info pfn to a mfn */
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void xen_hvm_resume_shared_info(void)
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{
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xen_hvm_connect_shared_info(__pa(xen_hvm_shared_info) >> PAGE_SHIFT);
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}
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#ifdef CONFIG_KEXEC
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static struct shared_info *xen_hvm_shared_info_kexec;
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static unsigned long xen_hvm_shared_info_pfn_kexec;
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/* Remember a pfn in MMIO space for kexec reboot */
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void __devinit xen_hvm_prepare_kexec(struct shared_info *sip, unsigned long pfn)
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{
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xen_hvm_shared_info_kexec = sip;
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xen_hvm_shared_info_pfn_kexec = pfn;
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}
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static void xen_hvm_syscore_shutdown(void)
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{
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struct xen_memory_reservation reservation = {
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.domid = DOMID_SELF,
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.nr_extents = 1,
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};
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unsigned long prev_pfn;
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int rc;
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if (!xen_hvm_shared_info_kexec)
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return;
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prev_pfn = __pa(xen_hvm_shared_info) >> PAGE_SHIFT;
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set_xen_guest_handle(reservation.extent_start, &prev_pfn);
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/* Move pfn to MMIO, disconnects previous pfn from mfn */
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xen_hvm_connect_shared_info(xen_hvm_shared_info_pfn_kexec);
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/* Update pointers, following hypercall is also a memory barrier */
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xen_hvm_set_shared_info(xen_hvm_shared_info_kexec);
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/* Allocate new mfn for previous pfn */
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do {
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rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
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if (rc == 0)
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msleep(123);
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} while (rc == 0);
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/* Make sure the previous pfn is really connected to a (new) mfn */
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BUG_ON(rc != 1);
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}
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static struct syscore_ops xen_hvm_syscore_ops = {
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.shutdown = xen_hvm_syscore_shutdown,
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};
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#endif
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/* Use a pfn in RAM, may move to MMIO before kexec. */
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static void __init xen_hvm_init_shared_info(void)
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{
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/* Remember pointer for resume */
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xen_hvm_shared_info = extend_brk(PAGE_SIZE, PAGE_SIZE);
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xen_hvm_connect_shared_info(__pa(xen_hvm_shared_info) >> PAGE_SHIFT);
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xen_hvm_set_shared_info(xen_hvm_shared_info);
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}
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#ifdef CONFIG_XEN_PVHVM
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static void __init init_hvm_pv_info(void)
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{
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int major, minor;
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@ -1646,9 +1553,6 @@ static void __init xen_hvm_guest_init(void)
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init_hvm_pv_info();
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xen_hvm_init_shared_info();
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#ifdef CONFIG_KEXEC
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register_syscore_ops(&xen_hvm_syscore_ops);
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#endif
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if (xen_feature(XENFEAT_hvm_callback_vector))
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xen_have_vector_callback = 1;
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