ghes_copy_tofrom_phys() takes different locks depending on in_nmi(). This doesn't work when we have multiple NMI-like notifications, that can interrupt each other.
Now that NOTIFY_SEA is always called as an NMI, 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: James Morse <[email protected]> --- Changes since v5: * Moved locking further out, to allow no-irq-masking in the future. drivers/acpi/apei/ghes.c | 40 +++++++++++++++++++++++++++++----------- 1 file changed, 29 insertions(+), 11 deletions(-) diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c index 2880547e13b8..ed8669a6c100 100644 --- a/drivers/acpi/apei/ghes.c +++ b/drivers/acpi/apei/ghes.c @@ -113,12 +113,13 @@ static DEFINE_MUTEX(ghes_list_mutex); * from BIOS to Linux can be determined only in NMI, IRQ or timer * 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 - * simultaneously. */ -static DEFINE_RAW_SPINLOCK(ghes_ioremap_lock_nmi); -static DEFINE_SPINLOCK(ghes_ioremap_lock_irq); + +/* + * Used by ghes_proc() to prevent non-NMI notifications from interacting. + * This also protects the FIX_APEI_GHES_IRQ fixmap slot. + */ +static DEFINE_SPINLOCK(ghes_notify_lock_irq); static struct gen_pool *ghes_estatus_pool; static unsigned long ghes_estatus_pool_size_request; @@ -291,7 +292,6 @@ 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; @@ -299,10 +299,8 @@ 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; @@ -316,10 +314,8 @@ 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); } } } @@ -928,8 +924,11 @@ 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); } @@ -937,9 +936,12 @@ 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; @@ -950,14 +952,17 @@ 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; } @@ -968,6 +973,7 @@ static struct notifier_block ghes_notifier_hed = { #ifdef CONFIG_ACPI_APEI_SEA static LIST_HEAD(ghes_sea); +static DEFINE_RAW_SPINLOCK(ghes_notify_lock_sea); /* * Return 0 only if one of the SEA error sources successfully reported an error @@ -975,7 +981,13 @@ static LIST_HEAD(ghes_sea); */ int ghes_notify_sea(void) { - return ghes_estatus_queue_notified(&ghes_sea); + int rv; + + raw_spin_lock(&ghes_notify_lock_sea); + rv = ghes_estatus_queue_notified(&ghes_sea); + raw_spin_unlock(&ghes_notify_lock_sea); + + return rv; } static void ghes_sea_add(struct ghes *ghes) @@ -1009,6 +1021,7 @@ static inline void ghes_sea_remove(struct ghes *ghes) { } static atomic_t ghes_in_nmi = ATOMIC_INIT(0); static LIST_HEAD(ghes_nmi); +static DEFINE_RAW_SPINLOCK(ghes_notify_lock_nmi); static int ghes_notify_nmi(unsigned int cmd, struct pt_regs *regs) { @@ -1017,8 +1030,10 @@ static int ghes_notify_nmi(unsigned int cmd, struct pt_regs *regs) if (!atomic_add_unless(&ghes_in_nmi, 1, 1)) return ret; + raw_spin_lock(&ghes_notify_lock_nmi); if (!ghes_estatus_queue_notified(&ghes_nmi)) ret = NMI_HANDLED; + raw_spin_unlock(&ghes_notify_lock_nmi); atomic_dec(&ghes_in_nmi); return ret; @@ -1060,6 +1075,7 @@ static int ghes_probe(struct platform_device *ghes_dev) { struct acpi_hest_generic *generic; struct ghes *ghes = NULL; + unsigned long flags; int rc = -EINVAL; @@ -1162,7 +1178,9 @@ 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; -- 2.19.0 _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
