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Commit b4370df2 authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Greg Kroah-Hartman
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Drivers: hv: vmbus: add special crash handler 



Full kernel hang is observed when kdump kernel starts after a crash. This
hang happens in vmbus_negotiate_version() function on
wait_for_completion() as Hyper-V host (Win2012R2 in my testing) never
responds to CHANNELMSG_INITIATE_CONTACT as it thinks the connection is
already established. We need to perform some mandatory minimalistic
cleanup before we start new kernel.

Reported-by: default avatarK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: default avatarK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d7646eaa

arch/x86/include/asm/mshyperv.h

+2 −0
Original line number Diff line number Diff line
@@ -22,4 +22,6 @@ void hv_remove_vmbus_irq(void); 


void hv_setup_kexec_handler(void (*handler)(void));

void hv_remove_kexec_handler(void);

void hv_setup_crash_handler(void (*handler)(struct pt_regs *regs));

void hv_remove_crash_handler(void);

#endif

arch/x86/kernel/cpu/mshyperv.c

+22 −0
Original line number Diff line number Diff line
@@ -35,6 +35,7 @@ struct ms_hyperv_info ms_hyperv; 
EXPORT_SYMBOL_GPL(ms_hyperv);



static void (*hv_kexec_handler)(void);

static void (*hv_crash_handler)(struct pt_regs *regs);



#if IS_ENABLED(CONFIG_HYPERV)

static void (*vmbus_handler)(void);
@@ -83,6 +84,18 @@ void hv_remove_kexec_handler(void) 
	hv_kexec_handler = NULL;

}

EXPORT_SYMBOL_GPL(hv_remove_kexec_handler);



void hv_setup_crash_handler(void (*handler)(struct pt_regs *regs))

{

	hv_crash_handler = handler;

}

EXPORT_SYMBOL_GPL(hv_setup_crash_handler);



void hv_remove_crash_handler(void)

{

	hv_crash_handler = NULL;

}

EXPORT_SYMBOL_GPL(hv_remove_crash_handler);

#endif



static void hv_machine_shutdown(void)
@@ -92,6 +105,14 @@ static void hv_machine_shutdown(void) 
	native_machine_shutdown();

}



static void hv_machine_crash_shutdown(struct pt_regs *regs)

{

	if (hv_crash_handler)

		hv_crash_handler(regs);

	native_machine_crash_shutdown(regs);

}





static uint32_t  __init ms_hyperv_platform(void)

{

	u32 eax;
@@ -165,6 +186,7 @@ static void __init ms_hyperv_init_platform(void) 
#endif



	machine_ops.shutdown = hv_machine_shutdown;

	machine_ops.crash_shutdown = hv_machine_crash_shutdown;

}



const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {

drivers/hv/vmbus_drv.c

+14 −0
Original line number Diff line number Diff line
@@ -1071,6 +1071,18 @@ static void hv_kexec_handler(void) 
	hv_cleanup();

};



static void hv_crash_handler(struct pt_regs *regs)

{

	vmbus_initiate_unload();

	/*

	 * In crash handler we can't schedule synic cleanup for all CPUs,

	 * doing the cleanup for current CPU only. This should be sufficient

	 * for kdump.

	 */

	hv_synic_cleanup(NULL);

	hv_cleanup();

};



static int __init hv_acpi_init(void)

{

	int ret, t;
@@ -1104,6 +1116,7 @@ static int __init hv_acpi_init(void) 
		goto cleanup;



	hv_setup_kexec_handler(hv_kexec_handler);

	hv_setup_crash_handler(hv_crash_handler);



	return 0;
@@ -1118,6 +1131,7 @@ static void __exit vmbus_exit(void) 
	int cpu;



	hv_remove_kexec_handler();

	hv_remove_crash_handler();

	vmbus_connection.conn_state = DISCONNECTED;

	hv_synic_clockevents_cleanup();

	vmbus_disconnect();