Commit 3b880cbe authored by James Morse's avatar James Morse Committed by Rafael J. Wysocki
Browse files

ACPI / APEI: Move locking to the notification helper 



ghes_copy_tofrom_phys() takes different locks depending on in_nmi().
This doesn't work if there are multiple NMI-like notifications, that
can interrupt each other.

Now that NOTIFY_SEA is always called in the same context, move the
lock-taking to the notification helper. The helper will always know
which lock to take. This avoids ghes_copy_tofrom_phys() taking a guess
based on in_nmi().

This splits NOTIFY_NMI and NOTIFY_SEA to use different locks. All
the other notifications use ghes_proc(), and are called in process
or IRQ context. Move the spin_lock_irqsave() around their ghes_proc()
calls.

Signed-off-by: default avatarJames Morse <james.morse@arm.com>
Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent d44f1b8d

drivers/acpi/apei/ghes.c

+25 −9
Original line number Diff line number Diff line
@@ -114,11 +114,10 @@ static DEFINE_MUTEX(ghes_list_mutex); 
 * handler, but general ioremap can not be used in atomic context, so

 * the fixmap is used instead.

 *

 * These 2 spinlocks are used to prevent the fixmap entries from being used

 * This spinlock is used to prevent the fixmap entry from being used

 * simultaneously.

 */

static DEFINE_RAW_SPINLOCK(ghes_ioremap_lock_nmi);

static DEFINE_SPINLOCK(ghes_ioremap_lock_irq);

static DEFINE_SPINLOCK(ghes_notify_lock_irq);



static struct gen_pool *ghes_estatus_pool;

static unsigned long ghes_estatus_pool_size_request;
@@ -287,7 +286,6 @@ static void ghes_copy_tofrom_phys(void *buffer, u64 paddr, u32 len, 
				  int from_phys)

{

	void __iomem *vaddr;

	unsigned long flags = 0;

	int in_nmi = in_nmi();

	u64 offset;

	u32 trunk;
@@ -295,10 +293,8 @@ static void ghes_copy_tofrom_phys(void *buffer, u64 paddr, u32 len, 
	while (len > 0) {

		offset = paddr - (paddr & PAGE_MASK);

		if (in_nmi) {

			raw_spin_lock(&ghes_ioremap_lock_nmi);

			vaddr = ghes_ioremap_pfn_nmi(paddr >> PAGE_SHIFT);

		} else {

			spin_lock_irqsave(&ghes_ioremap_lock_irq, flags);

			vaddr = ghes_ioremap_pfn_irq(paddr >> PAGE_SHIFT);

		}

		trunk = PAGE_SIZE - offset;
@@ -312,10 +308,8 @@ static void ghes_copy_tofrom_phys(void *buffer, u64 paddr, u32 len, 
		buffer += trunk;

		if (in_nmi) {

			ghes_iounmap_nmi();

			raw_spin_unlock(&ghes_ioremap_lock_nmi);

		} else {

			ghes_iounmap_irq();

			spin_unlock_irqrestore(&ghes_ioremap_lock_irq, flags);

		}

	}

}
@@ -729,8 +723,11 @@ static void ghes_add_timer(struct ghes *ghes) 
static void ghes_poll_func(struct timer_list *t)

{

	struct ghes *ghes = from_timer(ghes, t, timer);

	unsigned long flags;



	spin_lock_irqsave(&ghes_notify_lock_irq, flags);

	ghes_proc(ghes);

	spin_unlock_irqrestore(&ghes_notify_lock_irq, flags);

	if (!(ghes->flags & GHES_EXITING))

		ghes_add_timer(ghes);

}
@@ -738,9 +735,12 @@ static void ghes_poll_func(struct timer_list *t) 
static irqreturn_t ghes_irq_func(int irq, void *data)

{

	struct ghes *ghes = data;

	unsigned long flags;

	int rc;



	spin_lock_irqsave(&ghes_notify_lock_irq, flags);

	rc = ghes_proc(ghes);

	spin_unlock_irqrestore(&ghes_notify_lock_irq, flags);

	if (rc)

		return IRQ_NONE;
@@ -751,14 +751,17 @@ static int ghes_notify_hed(struct notifier_block *this, unsigned long event, 
			   void *data)

{

	struct ghes *ghes;

	unsigned long flags;

	int ret = NOTIFY_DONE;



	spin_lock_irqsave(&ghes_notify_lock_irq, flags);

	rcu_read_lock();

	list_for_each_entry_rcu(ghes, &ghes_hed, list) {

		if (!ghes_proc(ghes))

			ret = NOTIFY_OK;

	}

	rcu_read_unlock();

	spin_unlock_irqrestore(&ghes_notify_lock_irq, flags);



	return ret;

}
@@ -912,7 +915,14 @@ static LIST_HEAD(ghes_sea); 
 */

int ghes_notify_sea(void)

{

	return ghes_in_nmi_spool_from_list(&ghes_sea);

	static DEFINE_RAW_SPINLOCK(ghes_notify_lock_sea);

	int rv;



	raw_spin_lock(&ghes_notify_lock_sea);

	rv = ghes_in_nmi_spool_from_list(&ghes_sea);

	raw_spin_unlock(&ghes_notify_lock_sea);



	return rv;

}



static void ghes_sea_add(struct ghes *ghes)
@@ -945,13 +955,16 @@ static LIST_HEAD(ghes_nmi); 


static int ghes_notify_nmi(unsigned int cmd, struct pt_regs *regs)

{

	static DEFINE_RAW_SPINLOCK(ghes_notify_lock_nmi);

	int ret = NMI_DONE;



	if (!atomic_add_unless(&ghes_in_nmi, 1, 1))

		return ret;



	raw_spin_lock(&ghes_notify_lock_nmi);

	if (!ghes_in_nmi_spool_from_list(&ghes_nmi))

		ret = NMI_HANDLED;

	raw_spin_unlock(&ghes_notify_lock_nmi);



	atomic_dec(&ghes_in_nmi);

	return ret;
@@ -993,6 +1006,7 @@ static int ghes_probe(struct platform_device *ghes_dev) 
{

	struct acpi_hest_generic *generic;

	struct ghes *ghes = NULL;

	unsigned long flags;



	int rc = -EINVAL;
@@ -1095,7 +1109,9 @@ static int ghes_probe(struct platform_device *ghes_dev) 
	ghes_edac_register(ghes, &ghes_dev->dev);



	/* Handle any pending errors right away */

	spin_lock_irqsave(&ghes_notify_lock_irq, flags);

	ghes_proc(ghes);

	spin_unlock_irqrestore(&ghes_notify_lock_irq, flags);



	return 0;

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