On 11/08/15 10:14, Eric Auger wrote:
> Hi Marc,
> On 07/09/2015 03:19 PM, Marc Zyngier wrote:
>> So far, GICv3 has been used in with EOImode == 0. The effect of this
>> mode is to perform the priority drop and the deactivation of the
>> interrupt at the same time.
>>
>> While this works perfectly for Linux (we only have a single priority),
>> it causes issues when an interrupt is forwarded to a guest, and when
>> we want the guest to perform the EOI itself.
>>
>> For this case, the GIC architecture provides EOImode == 1, where:
>> - A write to ICC_EOIR1_EL1 drops the priority of the interrupt and leaves
>> it active. Other interrupts at the same priority level can now be taken,
>> but the active interrupt cannot be taken again
>> - A write to ICC_DIR_EL1 marks the interrupt as inactive, meaning it can
>> now be taken again.
>>
>> This patch converts the driver to be able to use this new mode, depending
>> on whether or not the kernel can behave as a hypervisor. No feature change.
>>
>> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
>> ---
>> drivers/irqchip/irq-gic-v3.c | 28 +++++++++++++++++++++++++---
>> include/linux/irqchip/arm-gic-v3.h | 9 +++++++++
>> 2 files changed, 34 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
>> index c52f7ba..49768fc 100644
>> --- a/drivers/irqchip/irq-gic-v3.c
>> +++ b/drivers/irqchip/irq-gic-v3.c
>> @@ -30,6 +30,7 @@
>> #include <asm/cputype.h>
>> #include <asm/exception.h>
>> #include <asm/smp_plat.h>
>> +#include <asm/virt.h>
>>
>> #include "irq-gic-common.h"
>> #include "irqchip.h"
>> @@ -50,6 +51,7 @@ struct gic_chip_data {
>> };
>>
>> static struct gic_chip_data gic_data __read_mostly;
>> +static struct static_key supports_deactivate = STATIC_KEY_INIT_TRUE;
>>
>> #define gic_data_rdist() (this_cpu_ptr(gic_data.rdists.rdist))
>> #define gic_data_rdist_rd_base() (gic_data_rdist()->rd_base)
>> @@ -293,7 +295,10 @@ static int gic_irq_get_irqchip_state(struct irq_data *d,
>>
>> static void gic_eoi_irq(struct irq_data *d)
>> {
>> - gic_write_eoir(gic_irq(d));
>> + if (static_key_true(&supports_deactivate))
>> + gic_write_dir(gic_irq(d));
>> + else
>> + gic_write_eoir(gic_irq(d));
>> }
>>
>> static int gic_set_type(struct irq_data *d, unsigned int type)
>> @@ -343,6 +348,10 @@ static asmlinkage void __exception_irq_entry gic_handle_irq(struct pt_regs *regs
>>
>> if (likely(irqnr > 15 && irqnr < 1020) || irqnr >= 8192) {
>> int err;
>> +
>> + if (static_key_true(&supports_deactivate))
>> + gic_write_eoir(irqnr);
>> +
>> err = handle_domain_irq(gic_data.domain, irqnr, regs);
>> if (err) {
>> WARN_ONCE(true, "Unexpected interrupt received!\n");
> shouldn't we DIR here as well in case of err (we did EOI before)?
Yes, we should, very good point. I'll fix that up.
> Besides Reviewed-by: Eric Auger <eric.auger@xxxxxxxxxx> if it can help.
>
Thanks!
M.
--
Jazz is not dead. It just smells funny...
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