From: Robert Richter <rrich...@cavium.com>
This patch implements Cavium ThunderX erratum 23154.
The gicv3 of ThunderX requires a modified version for reading the IAR
status to ensure data synchronization. Since this is in the fast-path
and called with each interrupt, runtime patching is used using jump
label patching for smallest overhead (no-op). This is the same
technique as used for tracepoints.
v2:
* implement code in a single asm() to keep instruction sequence
* added comment to the code that explains the erratum
* apply workaround also if running as guest, thus check MIDR
Signed-off-by: Robert Richter <rrich...@cavium.com>
---
drivers/irqchip/irq-gic-v3.c | 45 +++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 44 insertions(+), 1 deletion(-)
diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 1a91902be0b1..2f80a11621a0 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -107,7 +107,7 @@ static void gic_redist_wait_for_rwp(void)
}
/* Low level accessors */
-static u64 __maybe_unused gic_read_iar(void)
+static u64 gic_read_iar_common(void)
{
u64 irqstat;
@@ -115,6 +115,38 @@ static u64 __maybe_unused gic_read_iar(void)
return irqstat;
}
+/*
+ * Cavium ThunderX erratum 23154
+ *
+ * The gicv3 of ThunderX requires a modified version for reading the
+ * IAR status to ensure data synchronization (access to icc_iar1_el1
+ * is not sync'ed before and after).
+ */
+static u64 gic_read_iar_cavium_thunderx(void)
+{
+ u64 irqstat;
+
+ asm volatile(
+ "nop;nop;nop;nop\n\t"
+ "nop;nop;nop;nop\n\t"
+ "mrs_s %0, " __stringify(ICC_IAR1_EL1) "\n\t"
+ "nop;nop;nop;nop"
+ : "=r" (irqstat));
+ mb();
+
+ return irqstat;
+}
+
+struct static_key is_cavium_thunderx = STATIC_KEY_INIT_FALSE;
+
+static u64 __maybe_unused gic_read_iar(void)
+{
+ if (static_key_false(&is_cavium_thunderx))
+ return gic_read_iar_common();
+ else
+ return gic_read_iar_cavium_thunderx();
+}
+
static void __maybe_unused gic_write_pmr(u64 val)
{
asm volatile("msr_s " __stringify(ICC_PMR_EL1) ", %0" : : "r" (val));
@@ -766,8 +798,19 @@ static const struct irq_domain_ops gic_irq_domain_ops = {
.free = gic_irq_domain_free,
};
+static void gicv3_enable_cavium_thunderx(void *data)
+{
+ static_key_slow_inc(&is_cavium_thunderx);
+}
+
static const struct gic_capabilities gicv3_errata[] = {
{
+ .desc = "GIC: Cavium erratum 23154",
+ .iidr = 0xa100034c, /* ThunderX pass 1.x */
+ .iidr_mask = 0xffff0fff,
+ .init = gicv3_enable_cavium_thunderx,
+ },
+ {
}
};
--
2.1.1
--
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