Hi Robert,
On 30/06/15 15:14, Robert Richter wrote:
> From: Robert Richter <[email protected]>
>
> 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.
>
> Signed-off-by: Robert Richter <[email protected]>
> ---
> drivers/irqchip/irq-gic-v3.c | 37 ++++++++++++++++++++++++++++++++++++-
> 1 file changed, 36 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
> index f4bafc69cc18..57bb69686ec6 100644
> --- a/drivers/irqchip/irq-gic-v3.c
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -107,14 +107,38 @@ 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;
> +
> + asm volatile("mrs_s %0, " __stringify(ICC_IAR1_EL1) : "=r" (irqstat));
> + return irqstat;
> +}
> +
> +/* Cavium ThunderX erratum 23154 */
> +static u64 gic_read_iar_cavium_thunderx(void)
> {
> u64 irqstat;
>
> + asm volatile("nop;nop;nop;nop;");
> + asm volatile("nop;nop;nop;nop;");
> asm volatile("mrs_s %0, " __stringify(ICC_IAR1_EL1) : "=r" (irqstat));
> + asm volatile("nop;nop;nop;nop;");
> + 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));
> @@ -765,8 +789,19 @@ 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",
> + .id = 0xa100034c, /* ThunderX pass 1.x */
> + .mask = 0xffff0fff,
> + .init = gicv3_enable_cavium_thunderx,
> + },
> + {
> }
> };
>
>
How does this work when running a guest? Does the virtualized access
suffer from the same erratum? If that's the case, we need a better
workaround...
Thanks,
M.
--
Jazz is not dead. It just smells funny...
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
