Re: [PATCH kvm-unit-tests v2] arm64: timer: Speed up gic-timer-state check

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Hi Drew,

On 2020/2/11 23:41, Andrew Jones wrote:
On Tue, Feb 11, 2020 at 10:50:58PM +0800, Zenghui Yu wrote:
Hi Drew,

On 2020/2/11 21:37, Andrew Jones wrote:
Let's bail out of the wait loop if we see the expected state
to save over six seconds of run time. Make sure we wait a bit
before reading the registers and double check again after,
though, to somewhat mitigate the chance of seeing the expected
state by accident.

We also take this opportunity to push more IRQ state code to
the library.

Signed-off-by: Andrew Jones <drjones@xxxxxxxxxx>

[...]

+
+enum gic_irq_state gic_irq_state(int irq)

This is a *generic* name while this function only deals with PPI.
Maybe we can use something like gic_ppi_state() instead?  Or you
will have to take all interrupt types into account in a single
function, which is not a easy job I think.

Very good point.


+{
+	enum gic_irq_state state;
+	bool pending = false, active = false;
+	void *base;
+
+	assert(gic_common_ops);
+
+	switch (gic_version()) {
+	case 2:
+		base = gicv2_dist_base();
+		pending = readl(base + GICD_ISPENDR) & (1 << PPI(irq));
+		active = readl(base + GICD_ISACTIVER) & (1 << PPI(irq));
+		break;
+	case 3:
+		base = gicv3_sgi_base();
+		pending = readl(base + GICR_ISPENDR0) & (1 << PPI(irq));
+		active = readl(base + GICR_ISACTIVER0) & (1 << PPI(irq));

And you may also want to ensure that the 'irq' is valid for PPI().
Or personally, I'd just use a real PPI number (PPI(info->irq)) as
the input parameter of this function.

Indeed, if we want to make this a general function we should require
the caller to pass PPI(irq).


+		break;
+	}
+
+	if (!active && !pending)
+		state = GIC_IRQ_STATE_INACTIVE;
+	if (pending)
+		state = GIC_IRQ_STATE_PENDING;
+	if (active)
+		state = GIC_IRQ_STATE_ACTIVE;
+	if (active && pending)
+		state = GIC_IRQ_STATE_ACTIVE_PENDING;
+
+	return state;
+}


Otherwise,

Reviewed-by: Zenghui Yu <yuzenghui@xxxxxxxxxx>
Tested-by: Zenghui Yu <yuzenghui@xxxxxxxxxx>

Thanks, but I guess I should squash in changes to make this function more
general. My GIC/SPI skills are weak, so I'm not sure this is right,
especially because the SPI stuff doesn't yet have a user to validate it.

(I guess the PL031 can be another new user.)

However, if all reviewers think it's correct, then I'll squash it into
the arm/queue branch. I've added Andre and Eric to help review too.

Thanks,
drew


diff --git a/arm/timer.c b/arm/timer.c
index ae5fdbf54b35..44621b4f2967 100644
--- a/arm/timer.c
+++ b/arm/timer.c
@@ -189,9 +189,9 @@ static bool gic_timer_check_state(struct timer_info *info,
  	/* Wait for up to 1s for the GIC to sample the interrupt. */
  	for (i = 0; i < 10; i++) {
  		mdelay(100);
-		if (gic_irq_state(info->irq) == expected_state) {
+		if (gic_irq_state(PPI(info->irq)) == expected_state) {
  			mdelay(100);
-			if (gic_irq_state(info->irq) == expected_state)
+			if (gic_irq_state(PPI(info->irq)) == expected_state)
  				return true;
  		}
  	}
diff --git a/lib/arm/gic.c b/lib/arm/gic.c
index 0563b31132c8..3924dd1d1ee6 100644
--- a/lib/arm/gic.c
+++ b/lib/arm/gic.c
@@ -150,22 +150,37 @@ void gic_ipi_send_mask(int irq, const cpumask_t *dest)
  enum gic_irq_state gic_irq_state(int irq)
  {
  	enum gic_irq_state state;
-	bool pending = false, active = false;
-	void *base;
+	void *ispendr, *isactiver;
+	bool pending, active;
assert(gic_common_ops);

We can also assert that only interrupts with ID smaller than 1020
will be handled.

switch (gic_version()) {
  	case 2:
-		base = gicv2_dist_base();
-		pending = readl(base + GICD_ISPENDR) & (1 << PPI(irq));
-		active = readl(base + GICD_ISACTIVER) & (1 << PPI(irq));
+		ispendr = gicv2_dist_base() + GICD_ISPENDR;
+		isactiver = gicv2_dist_base() + GICD_ISACTIVER;
  		break;
  	case 3:
-		base = gicv3_sgi_base();
-		pending = readl(base + GICR_ISPENDR0) & (1 << PPI(irq));
-		active = readl(base + GICR_ISACTIVER0) & (1 << PPI(irq));
+		if (irq < GIC_NR_PRIVATE_IRQS) {
+			ispendr = gicv3_sgi_base() + GICR_ISPENDR0;
+			isactiver = gicv3_sgi_base() + GICR_ISACTIVER0;
+		} else {
+			ispendr = gicv3_dist_base() + GICD_ISPENDR;
+			isactiver = gicv3_dist_base() + GICD_ISACTIVER;
+		}
  		break;
+	default:
+		assert(0);
+	}
+
+	if (irq < GIC_NR_PRIVATE_IRQS) {
+		pending = readl(ispendr) & (1 << irq);
+		active = readl(isactiver) & (1 << irq);
+	} else {
+		int offset = (irq - GIC_FIRST_SPI) / 32;
+		int mask = 1 << ((irq - GIC_FIRST_SPI) % 32);

No need to minus GIC_FIRST_SPI.  And therefore these two cases
can actually be merged.

+		pending = readl(ispendr + offset) & mask;
+		active = readl(isactiver + offset) & mask;
  	}
if (!active && !pending)

Otherwise this looks good enough (to me) for now, and let's wait
other reviewers to comment.  I've used the following diff to give
the pl031 test a go (roughly written, not dig into PL031 so much),
it just works fine :)


Thanks,
Zenghui

diff --git a/arm/pl031.c b/arm/pl031.c
index 86035fa..2d4160f 100644
--- a/arm/pl031.c
+++ b/arm/pl031.c
@@ -118,11 +118,12 @@ static int check_rtc_freq(void)
 	return 0;
 }

-static bool gic_irq_pending(void)
+static bool gic_pl031_pending(void)
 {
-	uint32_t offset = (pl031_irq / 32) * 4;
+	enum gic_irq_state state = gic_irq_state(pl031_irq);

-	return readl(gic_ispendr + offset) & (1 << (pl031_irq & 31));
+	return state == GIC_IRQ_STATE_PENDING ||
+		state == GIC_IRQ_STATE_ACTIVE_PENDING;
 }

 static void gic_irq_unmask(void)

[...]
/* replace all gic_irq_pending() with gic_pl031_pending() */
[...]

diff --git a/lib/arm/gic.c b/lib/arm/gic.c
index 3924dd1..34d77e3 100644
--- a/lib/arm/gic.c
+++ b/lib/arm/gic.c
@@ -152,6 +152,7 @@ enum gic_irq_state gic_irq_state(int irq)
 	enum gic_irq_state state;
 	void *ispendr, *isactiver;
 	bool pending, active;
+	int offset, mask;

 	assert(gic_common_ops);

@@ -173,15 +174,10 @@ enum gic_irq_state gic_irq_state(int irq)
 		assert(0);
 	}

-	if (irq < GIC_NR_PRIVATE_IRQS) {
-		pending = readl(ispendr) & (1 << irq);
-		active = readl(isactiver) & (1 << irq);
-	} else {
-		int offset = (irq - GIC_FIRST_SPI) / 32;
-		int mask = 1 << ((irq - GIC_FIRST_SPI) % 32);
-		pending = readl(ispendr + offset) & mask;
-		active = readl(isactiver + offset) & mask;
-	}
+	offset = (irq / 32) * 4;
+	mask = 1 << (irq % 32);
+	pending = readl(ispendr + offset) & mask;
+	active = readl(isactiver + offset) & mask;

 	if (!active && !pending)
 		state = GIC_IRQ_STATE_INACTIVE;

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