Re: [Xen-devel] [PATCH v4 18/28] x86/vioapic: Hook interrupt delivery of vIOAPIC

[Chao Gao <chao.gao@xxxxxxxxx>]

On Mon, Feb 12, 2018 at 02:54:02PM +0000, Roger Pau Monné wrote:
>On Fri, Nov 17, 2017 at 02:22:25PM +0800, Chao Gao wrote:
>> When irq remapping is enabled, IOAPIC Redirection Entry may be in remapping
>> format. If that, generate an irq_remapping_request and call the common
>
>"If that's the case, ..."
>
>> VIOMMU abstraction's callback to handle this interrupt request. Device
>> model is responsible for checking the request's validity.
>
>What does this exactly mean? Device model is not involved in what the
>guest writes to the vIOAPIC RTE, so it's impossible for the device
>model to validate this in any way.

How about this description:
When irq remapping is enabled, IOAPIC Redirection Entry may be in remapping
format. If that's the case, an irq_remapping_request will be generated and
IOMMU-specific handler deals with this request. IOMMU-specific handler
will check whether the request is valid or not, report error via
IOMMU-specific machanism if invalid or otherwise transform the request to an
interrupt info (including interrupt destination, vector and trigger mode
etc.) according to IRT.

>
>> Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>
>> Signed-off-by: Lan Tianyu <tianyu.lan@xxxxxxxxx>
>> 
>> ---
>> v3:
>>  - use the new interface to check remapping format.
>> ---
>>  xen/arch/x86/hvm/vioapic.c   | 9 +++++++++
>>  xen/include/asm-x86/viommu.h | 9 +++++++++
>>  2 files changed, 18 insertions(+)
>> 
>> diff --git a/xen/arch/x86/hvm/vioapic.c b/xen/arch/x86/hvm/vioapic.c
>> index 97b419f..0f20e3f 100644
>> --- a/xen/arch/x86/hvm/vioapic.c
>> +++ b/xen/arch/x86/hvm/vioapic.c
>> @@ -30,6 +30,7 @@
>>  #include <xen/lib.h>
>>  #include <xen/errno.h>
>>  #include <xen/sched.h>
>> +#include <xen/viommu.h>
>>  #include <public/hvm/ioreq.h>
>>  #include <asm/hvm/io.h>
>>  #include <asm/hvm/vpic.h>
>> @@ -387,9 +388,17 @@ static void vioapic_deliver(struct hvm_vioapic 
>> *vioapic, unsigned int pin)
>>      struct vlapic *target;
>>      struct vcpu *v;
>>      unsigned int irq = vioapic->base_gsi + pin;
>> +    struct arch_irq_remapping_request request;
>>  
>>      ASSERT(spin_is_locked(&d->arch.hvm_domain.irq_lock));
>>  
>> +    irq_request_ioapic_fill(&request, vioapic->id, 
>> vioapic->redirtbl[pin].bits);
>> +    if ( viommu_check_irq_remapping(d, &request) )
>> +    {
>> +        viommu_handle_irq_request(d, &request);
>> +        return;
>> +    }
>
>Will this compile if you disable vIOMMU in Kconfig?

Yes. Will fix this by wrapping this fragment with #ifdef and #endif.

Thanks
Chao

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