linux-kernel - Re: [PATCH v3 08/16] irqchip/gic: Configure SGIs as standard interrupts

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Message-ID: <3378cd07b92e87a24f1db75f708424ee@kernel.org>
Date:   Wed, 16 Sep 2020 16:10:57 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Jon Hunter <jonathanh@...dia.com>
Cc:     Marek Szyprowski <m.szyprowski@...sung.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Sumit Garg <sumit.garg@...aro.org>, kernel-team@...roid.com,
        Florian Fainelli <f.fainelli@...il.com>,
        Russell King <linux@....linux.org.uk>,
        Jason Cooper <jason@...edaemon.net>,
        Saravana Kannan <saravanak@...gle.com>,
        Andrew Lunn <andrew@...n.ch>,
        Catalin Marinas <catalin.marinas@....com>,
        Gregory Clement <gregory.clement@...tlin.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        'Linux Samsung SOC' <linux-samsung-soc@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Will Deacon <will@...nel.org>,
        Valentin Schneider <Valentin.Schneider@....com>,
        linux-tegra <linux-tegra@...r.kernel.org>,
        linus.walleij@...aro.org
Subject: Re: [PATCH v3 08/16] irqchip/gic: Configure SGIs as standard
 interrupts

Hi Jon,

+Linus, who is facing a similar issue.

On 2020-09-16 15:16, Jon Hunter wrote:
> Hi Marc,
> 
> On 14/09/2020 14:06, Marek Szyprowski wrote:
>> Hi Marc,
>> 
>> On 01.09.2020 16:43, Marc Zyngier wrote:
>>> Change the way we deal with GIC SGIs by turning them into proper
>>> IRQs, and calling into the arch code to register the interrupt range
>>> instead of a callback.
>>> 
>>> Reviewed-by: Valentin Schneider <valentin.schneider@....com>
>>> Signed-off-by: Marc Zyngier <maz@...nel.org>
>> This patch landed in linux next-20200914 as commit ac063232d4b0
>> ("irqchip/gic: Configure SGIs as standard interrupts"). Sadly it 
>> breaks
>> booting of all Samsung Exynos 4210/4412 based boards (dual/quad ARM
>> Cortex A9 based). Here are the last lines from the bootlog:
> 
> I am observing the same thing on several Tegra boards (both arm and
> arm64). Bisect is pointing to this commit. Reverting this alone does 
> not
> appear to be enough to fix the issue.

Right, I am just massively by the GICv3 spec, and failed to remember
that ye olde GIC exposes the source CPU in AIR *and* wants it back, 
while
newer GICs deal with that transparently.

Can you try the patch below and let me know?

         M.

diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
index 98743afdaea6..56492bf8b6f9 100644
--- a/drivers/irqchip/irq-gic.c
+++ b/drivers/irqchip/irq-gic.c
@@ -121,9 +121,10 @@ static struct gic_chip_data 
gic_data[CONFIG_ARM_GIC_MAX_NR] __read_mostly;

  static struct gic_kvm_info gic_v2_kvm_info;

+static DEFINE_PER_CPU(u32, sgi_intid);
+
  #ifdef CONFIG_GIC_NON_BANKED
  static DEFINE_STATIC_KEY_FALSE(frankengic_key);
-static DEFINE_PER_CPU(u32, sgi_intid);

  static void enable_frankengic(void)
  {
@@ -135,16 +136,6 @@ static inline bool is_frankengic(void)
  	return static_branch_unlikely(&frankengic_key);
  }

-static inline void set_sgi_intid(u32 intid)
-{
-	this_cpu_write(sgi_intid, intid);
-}
-
-static inline u32 get_sgi_intid(void)
-{
-	return this_cpu_read(sgi_intid);
-}
-
  static inline void __iomem *__get_base(union gic_base *base)
  {
  	if (is_frankengic())
@@ -160,8 +151,6 @@ static inline void __iomem *__get_base(union 
gic_base *base)
  #define gic_data_cpu_base(d)	((d)->cpu_base.common_base)
  #define enable_frankengic()	do { } while(0)
  #define is_frankengic()		false
-#define set_sgi_intid(i)	do { } while(0)
-#define get_sgi_intid()		0
  #endif

  static inline void __iomem *gic_dist_base(struct irq_data *d)
@@ -236,8 +225,8 @@ static void gic_eoi_irq(struct irq_data *d)
  {
  	u32 hwirq = gic_irq(d);

-	if (is_frankengic() && hwirq < 16)
-		hwirq = get_sgi_intid();
+	if (hwirq < 16)
+		hwirq = this_cpu_read(sgi_intid);

  	writel_relaxed(hwirq, gic_cpu_base(d) + GIC_CPU_EOI);
  }
@@ -365,14 +354,13 @@ static void __exception_irq_entry 
gic_handle_irq(struct pt_regs *regs)
  			smp_rmb();

  			/*
-			 * Samsung's funky GIC encodes the source CPU in
-			 * GICC_IAR, leading to the deactivation to fail if
-			 * not written back as is to GICC_EOI.  Stash the
-			 * INTID away for gic_eoi_irq() to write back.
-			 * This only works because we don't nest SGIs...
+			 * The GIC encodes the source CPU in GICC_IAR,
+			 * leading to the deactivation to fail if not
+			 * written back as is to GICC_EOI.  Stash the INTID
+			 * away for gic_eoi_irq() to write back.  This only
+			 * works because we don't nest SGIs...
  			 */
-			if (is_frankengic())
-				set_sgi_intid(irqstat);
+			this_cpu_write(sgi_intid, intid);
  		}

  		handle_domain_irq(gic->domain, irqnr, regs);

-- 
Jazz is not dead. It just smells funny...