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x86/hyperv: Fix kexec panic/hang issues 

Currently the kexec kernel can panic or hang due to 2 causes:

1) hv_cpu_die() is not called upon kexec, so the hypervisor corrupts the
old VP Assist Pages when the kexec kernel runs. The same issue is fixed
for hibernation in commit 421f090c81 ("x86/hyperv: Suspend/resume the
VP assist page for hibernation"). Now fix it for kexec.

2) hyperv_cleanup() is called too early. In the kexec path, the other CPUs
are stopped in hv_machine_shutdown() -> native_machine_shutdown(), so
between hv_kexec_handler() and native_machine_shutdown(), the other CPUs
can still try to access the hypercall page and cause panic. The workaround
"hv_hypercall_pg = NULL;" in hyperv_cleanup() is unreliabe. Move
hyperv_cleanup() to a better place.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20201222065541.24312-1-decui@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
zero-sugar-mainline-defconfig
Dexuan Cui 2020-12-21 22:55:41 -08:00 committed by Wei Liu
parent e71ba9452f
commit dfe94d4086
4 changed files with 24 additions and 2 deletions
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4
arch/x86/hyperv/hv_init.c
View File

@ -16,6 +16,7 @@
#include <asm/hyperv-tlfs.h>
#include <asm/mshyperv.h>
#include <asm/idtentry.h>
#include <linux/kexec.h>
#include <linux/version.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>
@ -26,6 +27,8 @@
#include <linux/syscore_ops.h>
#include <clocksource/hyperv_timer.h>
int hyperv_init_cpuhp;
void *hv_hypercall_pg;
EXPORT_SYMBOL_GPL(hv_hypercall_pg);
@ -401,6 +404,7 @@ void __init hyperv_init(void)
register_syscore_ops(&hv_syscore_ops);
hyperv_init_cpuhp = cpuhp;
return;
remove_cpuhp_state:

2
arch/x86/include/asm/mshyperv.h
View File

@ -74,6 +74,8 @@ static inline void hv_disable_stimer0_percpu_irq(int irq) {}
#if IS_ENABLED(CONFIG_HYPERV)
extern int hyperv_init_cpuhp;
extern void *hv_hypercall_pg;
extern void __percpu **hyperv_pcpu_input_arg;

18
arch/x86/kernel/cpu/mshyperv.c
View File

@ -135,14 +135,32 @@ static void hv_machine_shutdown(void)
{
if (kexec_in_progress && hv_kexec_handler)
hv_kexec_handler();
/*
* Call hv_cpu_die() on all the CPUs, otherwise later the hypervisor
* corrupts the old VP Assist Pages and can crash the kexec kernel.
*/
if (kexec_in_progress && hyperv_init_cpuhp > 0)
cpuhp_remove_state(hyperv_init_cpuhp);
/* The function calls stop_other_cpus(). */
native_machine_shutdown();
/* Disable the hypercall page when there is only 1 active CPU. */
if (kexec_in_progress)
hyperv_cleanup();
}
static void hv_machine_crash_shutdown(struct pt_regs *regs)
{
if (hv_crash_handler)
hv_crash_handler(regs);
/* The function calls crash_smp_send_stop(). */
native_machine_crash_shutdown(regs);
/* Disable the hypercall page when there is only 1 active CPU. */
hyperv_cleanup();
}
#endif /* CONFIG_KEXEC_CORE */
#endif /* CONFIG_HYPERV */

2
drivers/hv/vmbus_drv.c
View File

@ -2550,7 +2550,6 @@ static void hv_kexec_handler(void)
/* Make sure conn_state is set as hv_synic_cleanup checks for it */
mb();
cpuhp_remove_state(hyperv_cpuhp_online);
hyperv_cleanup();
};
static void hv_crash_handler(struct pt_regs *regs)
@ -2566,7 +2565,6 @@ static void hv_crash_handler(struct pt_regs *regs)
cpu = smp_processor_id();
hv_stimer_cleanup(cpu);
hv_synic_disable_regs(cpu);
hyperv_cleanup();
};
static int hv_synic_suspend(void)