x86/xen: Support kexec/kdump in HVM guests by doing a soft reset (0b34a166) · Commits · 戴 / test

Currently there is a number of issues preventing PVHVM Xen guests from doing successful kexec/kdump: - Bound event channels. - Registered vcpu_info. - PIRQ/emuirq mappings. - shared_info frame after XENMAPSPACE_shared_info operation. - Active grant mappings. Basically, newly booted kernel stumbles upon already set up Xen interfaces and there is no way to reestablish them. In Xen-4.7 a new feature called 'soft reset' is coming. A guest performing kexec/kdump operation is supposed to call SCHEDOP_shutdown hypercall with SHUTDOWN_soft_reset reason before jumping to new kernel. Hypervisor (with some help from toolstack) will do full domain cleanup (but keeping its memory and vCPU contexts intact) returning the guest to the state it had when it was first booted and thus allowing it to start over. Doing SHUTDOWN_soft_reset on Xen hypervisors which don't support it is probably OK as by default all unknown shutdown reasons cause domain destroy with a message in toolstack log: 'Unknown shutdown reason code 5. Destroying domain.' which gives a clue to what the problem is and eliminates false expectations. Signed-off-by:

Vitaly Kuznetsov <vkuznets@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by:

David Vrabel <david.vrabel@citrix.com>

arch/x86/xen/enlighten.c

+23 −0

Original line number	Diff line number	Diff line
		@@ -33,6 +33,10 @@
		#include <linux/memblock.h>
		#include <linux/edd.h>

		#ifdef CONFIG_KEXEC_CORE
		#include <linux/kexec.h>
		#endif

		#include <xen/xen.h>
		#include <xen/events.h>
		#include <xen/interface/xen.h>
		@@ -1808,6 +1812,21 @@ static struct notifier_block xen_hvm_cpu_notifier = {
		.notifier_call = xen_hvm_cpu_notify,
		};

		#ifdef CONFIG_KEXEC_CORE
		static void xen_hvm_shutdown(void)
		{
		native_machine_shutdown();
		if (kexec_in_progress)
		xen_reboot(SHUTDOWN_soft_reset);
		}

		static void xen_hvm_crash_shutdown(struct pt_regs *regs)
		{
		native_machine_crash_shutdown(regs);
		xen_reboot(SHUTDOWN_soft_reset);
		}
		#endif

		static void __init xen_hvm_guest_init(void)
		{
		if (xen_pv_domain())
		@@ -1827,6 +1846,10 @@ static void __init xen_hvm_guest_init(void)
		x86_init.irqs.intr_init = xen_init_IRQ;
		xen_hvm_init_time_ops();
		xen_hvm_init_mmu_ops();
		#ifdef CONFIG_KEXEC_CORE
		machine_ops.shutdown = xen_hvm_shutdown;
		machine_ops.crash_shutdown = xen_hvm_crash_shutdown;
		#endif
		}
		#endif

include/xen/interface/sched.h

+8 −0

Original line number	Diff line number	Diff line
		@@ -107,5 +107,13 @@ struct sched_watchdog {
		#define SHUTDOWN_suspend 2 /* Clean up, save suspend info, kill. */
		#define SHUTDOWN_crash 3 /* Tell controller we've crashed. */
		#define SHUTDOWN_watchdog 4 /* Restart because watchdog time expired. */
		/*
		* Domain asked to perform 'soft reset' for it. The expected behavior is to
		* reset internal Xen state for the domain returning it to the point where it
		* was created but leaving the domain's memory contents and vCPU contexts
		* intact. This will allow the domain to start over and set up all Xen specific
		* interfaces again.
		*/
		#define SHUTDOWN_soft_reset 5

		#endif /* __XEN_PUBLIC_SCHED_H__ */

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