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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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00e37bdb01
Currently kexec in a PVonHVM guest fails with a triple fault because the new kernel overwrites the shared info page. The exact failure depends on the size of the kernel image. This patch moves the pfn from RAM into MMIO space before the kexec boot. 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. Signed-off-by: Olaf Hering <olaf@aepfle.de> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
115 lines
3.7 KiB
C
115 lines
3.7 KiB
C
#ifndef _XEN_EVENTS_H
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#define _XEN_EVENTS_H
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#include <linux/interrupt.h>
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#include <xen/interface/event_channel.h>
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#include <asm/xen/hypercall.h>
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#include <asm/xen/events.h>
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int bind_evtchn_to_irq(unsigned int evtchn);
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int bind_evtchn_to_irqhandler(unsigned int evtchn,
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irq_handler_t handler,
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unsigned long irqflags, const char *devname,
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void *dev_id);
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int bind_virq_to_irq(unsigned int virq, unsigned int cpu);
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int bind_virq_to_irqhandler(unsigned int virq, unsigned int cpu,
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irq_handler_t handler,
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unsigned long irqflags, const char *devname,
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void *dev_id);
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int bind_ipi_to_irqhandler(enum ipi_vector ipi,
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unsigned int cpu,
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irq_handler_t handler,
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unsigned long irqflags,
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const char *devname,
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void *dev_id);
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int bind_interdomain_evtchn_to_irqhandler(unsigned int remote_domain,
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unsigned int remote_port,
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irq_handler_t handler,
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unsigned long irqflags,
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const char *devname,
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void *dev_id);
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/*
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* Common unbind function for all event sources. Takes IRQ to unbind from.
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* Automatically closes the underlying event channel (even for bindings
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* made with bind_evtchn_to_irqhandler()).
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*/
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void unbind_from_irqhandler(unsigned int irq, void *dev_id);
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/*
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* Allow extra references to event channels exposed to userspace by evtchn
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*/
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int evtchn_make_refcounted(unsigned int evtchn);
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int evtchn_get(unsigned int evtchn);
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void evtchn_put(unsigned int evtchn);
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void xen_send_IPI_one(unsigned int cpu, enum ipi_vector vector);
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int resend_irq_on_evtchn(unsigned int irq);
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void rebind_evtchn_irq(int evtchn, int irq);
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static inline void notify_remote_via_evtchn(int port)
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{
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struct evtchn_send send = { .port = port };
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(void)HYPERVISOR_event_channel_op(EVTCHNOP_send, &send);
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}
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void notify_remote_via_irq(int irq);
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void xen_irq_resume(void);
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void xen_hvm_prepare_kexec(struct shared_info *sip, unsigned long pfn);
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/* Clear an irq's pending state, in preparation for polling on it */
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void xen_clear_irq_pending(int irq);
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void xen_set_irq_pending(int irq);
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bool xen_test_irq_pending(int irq);
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/* Poll waiting for an irq to become pending. In the usual case, the
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irq will be disabled so it won't deliver an interrupt. */
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void xen_poll_irq(int irq);
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/* Poll waiting for an irq to become pending with a timeout. In the usual case,
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* the irq will be disabled so it won't deliver an interrupt. */
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void xen_poll_irq_timeout(int irq, u64 timeout);
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/* Determine the IRQ which is bound to an event channel */
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unsigned irq_from_evtchn(unsigned int evtchn);
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/* Xen HVM evtchn vector callback */
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void xen_hvm_callback_vector(void);
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extern int xen_have_vector_callback;
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int xen_set_callback_via(uint64_t via);
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void xen_evtchn_do_upcall(struct pt_regs *regs);
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void xen_hvm_evtchn_do_upcall(void);
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/* Bind a pirq for a physical interrupt to an irq. */
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int xen_bind_pirq_gsi_to_irq(unsigned gsi,
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unsigned pirq, int shareable, char *name);
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#ifdef CONFIG_PCI_MSI
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/* Allocate a pirq for a MSI style physical interrupt. */
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int xen_allocate_pirq_msi(struct pci_dev *dev, struct msi_desc *msidesc);
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/* Bind an PSI pirq to an irq. */
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int xen_bind_pirq_msi_to_irq(struct pci_dev *dev, struct msi_desc *msidesc,
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int pirq, int vector, const char *name,
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domid_t domid);
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#endif
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/* De-allocates the above mentioned physical interrupt. */
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int xen_destroy_irq(int irq);
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/* Return irq from pirq */
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int xen_irq_from_pirq(unsigned pirq);
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/* Return the pirq allocated to the irq. */
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int xen_pirq_from_irq(unsigned irq);
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/* Return the irq allocated to the gsi */
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int xen_irq_from_gsi(unsigned gsi);
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/* Determine whether to ignore this IRQ if it is passed to a guest. */
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int xen_test_irq_shared(int irq);
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#endif /* _XEN_EVENTS_H */
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