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SubjectRe: [PATCH] x86/irq: hide HYP in /proc/interrupts when not on Xen/Hyper-V
On 07/06/2015 09:57 AM, Andrew Jones wrote:
> On Sat, Jul 04, 2015 at 10:26:53AM +0200, Ingo Molnar wrote:
>> * Vitaly Kuznetsov <vkuznets@redhat.com> wrote:
>>
>>> Hypervisor callback interrupts are only accounted on Xen/Hyper-V and we
>>> detect hypervisor's type in early boot. There is no point in having
>>> always-zero HYP: line on other hypervisors or bare metal.
>>>
>>> Suggested-by: Radim Krčmář <rkrcmar@redhat.com>
>>> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
>>> ---
>>> arch/x86/kernel/irq.c | 13 +++++++++----
>>> 1 file changed, 9 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
>>> index 88b36648..0c82064 100644
>>> --- a/arch/x86/kernel/irq.c
>>> +++ b/arch/x86/kernel/irq.c
>>> @@ -18,6 +18,7 @@
>>> #include <asm/mce.h>
>>> #include <asm/hw_irq.h>
>>> #include <asm/desc.h>
>>> +#include <asm/hypervisor.h>
>>>
>>> #define CREATE_TRACE_POINTS
>>> #include <asm/trace/irq_vectors.h>
>>> @@ -139,10 +140,14 @@ int arch_show_interrupts(struct seq_file *p, int prec)
>>> seq_puts(p, " Machine check polls\n");
>>> #endif
>>> #if IS_ENABLED(CONFIG_HYPERV) || defined(CONFIG_XEN)
>>> - seq_printf(p, "%*s: ", prec, "HYP");
>>> - for_each_online_cpu(j)
>>> - seq_printf(p, "%10u ", irq_stats(j)->irq_hv_callback_count);
>>> - seq_puts(p, " Hypervisor callback interrupts\n");
>>> + if (x86_hyper == &x86_hyper_ms_hyperv ||
>>> + x86_hyper == &x86_hyper_xen) {
>>> + seq_printf(p, "%*s: ", prec, "HYP");
>>> + for_each_online_cpu(j)
>>> + seq_printf(p, "%10u ",
>>> + irq_stats(j)->irq_hv_callback_count);
>>> + seq_puts(p, " Hypervisor callback interrupts\n");
>>> + }
>> So I think we should simplify this to:
>>
>> if (x86_hyper) {
>> ...
>> }
>>
>> this will print the HYP line on hypervisors that don't use
>> HYPERVISOR_CALLBACK_VECTOR, but it will make it a lot more self-maintaining, we
>> won't accidentally skip this line on hypervisors that start using the callback
>> IRQ.
> This is a good point. When virt stuff creeps out, it's easy to lose track of
> it. But, I would prefer that vmware and kvm guests don't have to have a
> meaningless counter in /proc/interrupts. Also, for xen, I see that it only
> matters for x86. ARM xen builds would also have a meaningless counter. Maybe
> we should add a flags member to hypervisor_x86, and start using that in
> these types of situations.

This is all x86 arch code so I don't see how it will make any difference
to Xen on ARM.


-boris



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