From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f71.google.com (mail-oi0-f71.google.com [209.85.218.71]) by kanga.kvack.org (Postfix) with ESMTP id 6AE576B0277 for ; Tue, 26 Jun 2018 13:02:24 -0400 (EDT) Received: by mail-oi0-f71.google.com with SMTP id 130-v6so5713647oii.8 for ; Tue, 26 Jun 2018 10:02:24 -0700 (PDT) Received: from foss.arm.com (foss.arm.com. [217.140.101.70]) by mx.google.com with ESMTP id l45-v6si609981ota.212.2018.06.26.10.02.22 for ; Tue, 26 Jun 2018 10:02:23 -0700 (PDT) From: James Morse Subject: [PATCH v5 08/20] ACPI / APEI: Move locking to the notification helper Date: Tue, 26 Jun 2018 18:01:04 +0100 Message-Id: <20180626170116.25825-9-james.morse@arm.com> In-Reply-To: <20180626170116.25825-1-james.morse@arm.com> References: <20180626170116.25825-1-james.morse@arm.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-acpi@vger.kernel.org Cc: kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, Borislav Petkov , Marc Zyngier , Christoffer Dall , Will Deacon , Catalin Marinas , Naoya Horiguchi , Rafael Wysocki , Len Brown , Tony Luck , Tyler Baicar , Dongjiu Geng , Xie XiuQi , Punit Agrawal , jonathan.zhang@cavium.com, James Morse 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() into ghes_proc(). Signed-off-by: James Morse --- drivers/acpi/apei/ghes.c | 38 +++++++++++++++++++++++++------------- 1 file changed, 25 insertions(+), 13 deletions(-) diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c index 2880547e13b8..f30e6fae57c0 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); } } } @@ -879,6 +875,9 @@ static int ghes_ack_error(struct acpi_hest_generic_v2 *gv2) static int ghes_proc(struct ghes *ghes) { int rc; + unsigned long flags; + + spin_lock_irqsave(&ghes_notify_lock_irq, flags); rc = ghes_read_estatus(ghes, 0); if (rc) @@ -898,14 +897,17 @@ static int ghes_proc(struct ghes *ghes) ghes_clear_estatus(ghes); if (rc == -ENOENT) - return rc; + goto unlock; /* * GHESv2 type HEST entries introduce support for error acknowledgment, * so only acknowledge the error if this support is present. */ if (is_hest_type_generic_v2(ghes)) - return ghes_ack_error(ghes->generic_v2); + rc = ghes_ack_error(ghes->generic_v2); + +unlock: + spin_unlock_irqrestore(&ghes_notify_lock_irq, flags); return rc; } @@ -968,6 +970,7 @@ 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 +978,13 @@ 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 +1018,7 @@ 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 +1027,10 @@ 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; -- 2.17.1