Drivers: hv: move panic report code from vmbus to hv early init code

The panic reporting code was added in commit 81b18bce48af
("Drivers: HV: Send one page worth of kmsg dump over Hyper-V during panic")

It was added to the vmbus driver. The panic reporting has no dependence
on vmbus, and can be enabled at an earlier boot time when Hyper-V is
initialized.

This patch moves the panic reporting code out of vmbus. There is no
functionality changes. During moving, also refactored some cleanup
functions into hv_kmsg_dump_unregister().

Signed-off-by: Long Li <longli@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/1682030946-6372-1-git-send-email-longli@linuxonhyperv.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>

1 files changed, 0 insertions, 199 deletions

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 19a0069dc4a9..309c78ce1d30 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -30,7 +30,6 @@
 #include <linux/panic_notifier.h>
 #include <linux/ptrace.h>
 #include <linux/screen_info.h>
-#include <linux/kdebug.h>
 #include <linux/efi.h>
 #include <linux/random.h>
 #include <linux/kernel.h>
@@ -50,8 +49,6 @@ static struct device  *hv_dev;
 
 static int hyperv_cpuhp_online;
 
-static void *hv_panic_page;
-
 static long __percpu *vmbus_evt;
 
 /* Values parsed from ACPI DSDT */
@@ -59,18 +56,6 @@ int vmbus_irq;
 int vmbus_interrupt;
 
 /*
- * Boolean to control whether to report panic messages over Hyper-V.
- *
- * It can be set via /proc/sys/kernel/hyperv_record_panic_msg
- */
-static int sysctl_record_panic_msg = 1;
-
-static int hyperv_report_reg(void)
-{
-	return !sysctl_record_panic_msg || !hv_panic_page;
-}
-
-/*
  * The panic notifier below is responsible solely for unloading the
  * vmbus connection, which is necessary in a panic event.
  *
@@ -90,54 +75,6 @@ static struct notifier_block hyperv_panic_vmbus_unload_block = {
 	.priority	= INT_MIN + 1, /* almost the latest one to execute */
 };
 
-static int hv_die_panic_notify_crash(struct notifier_block *self,
-				     unsigned long val, void *args);
-
-static struct notifier_block hyperv_die_report_block = {
-	.notifier_call = hv_die_panic_notify_crash,
-};
-static struct notifier_block hyperv_panic_report_block = {
-	.notifier_call = hv_die_panic_notify_crash,
-};
-
-/*
- * The following callback works both as die and panic notifier; its
- * goal is to provide panic information to the hypervisor unless the
- * kmsg dumper is used [see hv_kmsg_dump()], which provides more
- * information but isn't always available.
- *
- * Notice that both the panic/die report notifiers are registered only
- * if we have the capability HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE set.
- */
-static int hv_die_panic_notify_crash(struct notifier_block *self,
-				     unsigned long val, void *args)
-{
-	struct pt_regs *regs;
-	bool is_die;
-
-	/* Don't notify Hyper-V unless we have a die oops event or panic. */
-	if (self == &hyperv_panic_report_block) {
-		is_die = false;
-		regs = current_pt_regs();
-	} else { /* die event */
-		if (val != DIE_OOPS)
-			return NOTIFY_DONE;
-
-		is_die = true;
-		regs = ((struct die_args *)args)->regs;
-	}
-
-	/*
-	 * Hyper-V should be notified only once about a panic/die. If we will
-	 * be calling hv_kmsg_dump() later with kmsg data, don't do the
-	 * notification here.
-	 */
-	if (hyperv_report_reg())
-		hyperv_report_panic(regs, val, is_die);
-
-	return NOTIFY_DONE;
-}
-
 static const char *fb_mmio_name = "fb_range";
 static struct resource *fb_mmio;
 static struct resource *hyperv_mmio;
@@ -1380,98 +1317,6 @@ static irqreturn_t vmbus_percpu_isr(int irq, void *dev_id)
 }
 
 /*
- * Callback from kmsg_dump. Grab as much as possible from the end of the kmsg
- * buffer and call into Hyper-V to transfer the data.
- */
-static void hv_kmsg_dump(struct kmsg_dumper *dumper,
-			 enum kmsg_dump_reason reason)
-{
-	struct kmsg_dump_iter iter;
-	size_t bytes_written;
-
-	/* We are only interested in panics. */
-	if ((reason != KMSG_DUMP_PANIC) || (!sysctl_record_panic_msg))
-		return;
-
-	/*
-	 * Write dump contents to the page. No need to synchronize; panic should
-	 * be single-threaded.
-	 */
-	kmsg_dump_rewind(&iter);
-	kmsg_dump_get_buffer(&iter, false, hv_panic_page, HV_HYP_PAGE_SIZE,
-			     &bytes_written);
-	if (!bytes_written)
-		return;
-	/*
-	 * P3 to contain the physical address of the panic page & P4 to
-	 * contain the size of the panic data in that page. Rest of the
-	 * registers are no-op when the NOTIFY_MSG flag is set.
-	 */
-	hv_set_register(HV_REGISTER_CRASH_P0, 0);
-	hv_set_register(HV_REGISTER_CRASH_P1, 0);
-	hv_set_register(HV_REGISTER_CRASH_P2, 0);
-	hv_set_register(HV_REGISTER_CRASH_P3, virt_to_phys(hv_panic_page));
-	hv_set_register(HV_REGISTER_CRASH_P4, bytes_written);
-
-	/*
-	 * Let Hyper-V know there is crash data available along with
-	 * the panic message.
-	 */
-	hv_set_register(HV_REGISTER_CRASH_CTL,
-	       (HV_CRASH_CTL_CRASH_NOTIFY | HV_CRASH_CTL_CRASH_NOTIFY_MSG));
-}
-
-static struct kmsg_dumper hv_kmsg_dumper = {
-	.dump = hv_kmsg_dump,
-};
-
-static void hv_kmsg_dump_register(void)
-{
-	int ret;
-
-	hv_panic_page = hv_alloc_hyperv_zeroed_page();
-	if (!hv_panic_page) {
-		pr_err("Hyper-V: panic message page memory allocation failed\n");
-		return;
-	}
-
-	ret = kmsg_dump_register(&hv_kmsg_dumper);
-	if (ret) {
-		pr_err("Hyper-V: kmsg dump register error 0x%x\n", ret);
-		hv_free_hyperv_page((unsigned long)hv_panic_page);
-		hv_panic_page = NULL;
-	}
-}
-
-static struct ctl_table_header *hv_ctl_table_hdr;
-
-/*
- * sysctl option to allow the user to control whether kmsg data should be
- * reported to Hyper-V on panic.
- */
-static struct ctl_table hv_ctl_table[] = {
-	{
-		.procname       = "hyperv_record_panic_msg",
-		.data           = &sysctl_record_panic_msg,
-		.maxlen         = sizeof(int),
-		.mode           = 0644,
-		.proc_handler   = proc_dointvec_minmax,
-		.extra1		= SYSCTL_ZERO,
-		.extra2		= SYSCTL_ONE
-	},
-	{}
-};
-
-static struct ctl_table hv_root_table[] = {
-	{
-		.procname	= "kernel",
-		.mode		= 0555,
-		.child		= hv_ctl_table
-	},
-	{}
-};
-
-/*
  * vmbus_bus_init -Main vmbus driver initialization routine.
  *
  * Here, we
@@ -1534,38 +1379,6 @@ static int vmbus_bus_init(void)
 	if (ret)
 		goto err_connect;
 
-	if (hv_is_isolation_supported())
-		sysctl_record_panic_msg = 0;
-
-	/*
-	 * Only register if the crash MSRs are available
-	 */
-	if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
-		u64 hyperv_crash_ctl;
-		/*
-		 * Panic message recording (sysctl_record_panic_msg)
-		 * is enabled by default in non-isolated guests and
-		 * disabled by default in isolated guests; the panic
-		 * message recording won't be available in isolated
-		 * guests should the following registration fail.
-		 */
-		hv_ctl_table_hdr = register_sysctl_table(hv_root_table);
-		if (!hv_ctl_table_hdr)
-			pr_err("Hyper-V: sysctl table register error");
-
-		/*
-		 * Register for panic kmsg callback only if the right
-		 * capability is supported by the hypervisor.
-		 */
-		hyperv_crash_ctl = hv_get_register(HV_REGISTER_CRASH_CTL);
-		if (hyperv_crash_ctl & HV_CRASH_CTL_CRASH_NOTIFY_MSG)
-			hv_kmsg_dump_register();
-
-		register_die_notifier(&hyperv_die_report_block);
-		atomic_notifier_chain_register(&panic_notifier_list,
-						&hyperv_panic_report_block);
-	}
-
 	/*
 	 * Always register the vmbus unload panic notifier because we
 	 * need to shut the VMbus channel connection on panic.
@@ -1590,8 +1403,6 @@ err_alloc:
 	}
 err_setup:
 	bus_unregister(&hv_bus);
-	unregister_sysctl_table(hv_ctl_table_hdr);
-	hv_ctl_table_hdr = NULL;
 	return ret;
 }
 
@@ -2887,13 +2698,6 @@ static void __exit vmbus_exit(void)
 	vmbus_free_channels();
 	kfree(vmbus_connection.channels);
 
-	if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
-		kmsg_dump_unregister(&hv_kmsg_dumper);
-		unregister_die_notifier(&hyperv_die_report_block);
-		atomic_notifier_chain_unregister(&panic_notifier_list,
-						&hyperv_panic_report_block);
-	}
-
 	/*
 	 * The vmbus panic notifier is always registered, hence we should
 	 * also unconditionally unregister it here as well.
@@ -2901,9 +2705,6 @@ static void __exit vmbus_exit(void)
 	atomic_notifier_chain_unregister(&panic_notifier_list,
 					&hyperv_panic_vmbus_unload_block);
 
-	free_page((unsigned long)hv_panic_page);
-	unregister_sysctl_table(hv_ctl_table_hdr);
-	hv_ctl_table_hdr = NULL;
 	bus_unregister(&hv_bus);
 
 	cpuhp_remove_state(hyperv_cpuhp_online);