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Message-ID: <c0b2454c-3945-debf-f991-79139413f370@linux.microsoft.com>
Date:   Thu, 6 Apr 2023 11:41:18 +0530
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Subject: Re: [PATCH] PCI: hv: Use nested hypercall for retargeting interrupts
Content-Language: en-US
To:     Wei Liu <wei.liu@kernel.org>
Cc:     jinankjain@microsoft.com, kys@microsoft.com,
        haiyangz@microsoft.com, decui@microsoft.com, lpieralisi@kernel.org,
        kw@linux.com, robh@kernel.org, bhelgaas@google.com,
        linux-hyperv@vger.kernel.org, linux-pci@vger.kernel.org,
        linux-kernel@vger.kernel.org, nunodasneves@linux.microsoft.com
References: <20230404113546.856813-1-jinankjain@linux.microsoft.com>
 <ZC4BlSo0D1uNliFk@liuwe-devbox-debian-v2>
From:   Jinank Jain <jinankjain@linux.microsoft.com>
In-Reply-To: <ZC4BlSo0D1uNliFk@liuwe-devbox-debian-v2>
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This was observed while testing pass-through PCI devices on the nested 
MSHV setup.

Regards,

Jinank

On 4/6/2023 4:47 AM, Wei Liu wrote:
> On Tue, Apr 04, 2023 at 11:35:46AM +0000, Jinank Jain wrote:
>> In case of nested MSHV, retargeting interrupt hypercall should be sent
>> to L0 hypervisor instead of L1 hypervisor.
>>
>> Signed-off-by: Jinank Jain <jinankjain@linux.microsoft.com>
> While I think this is a sensible change -- how did you discover this?
> Can you provide a bit more information?
>
>> ---
>>   drivers/pci/controller/pci-hyperv.c | 10 ++++++++--
>>   1 file changed, 8 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
>> index f33370b75628..2123f632ecf7 100644
>> --- a/drivers/pci/controller/pci-hyperv.c
>> +++ b/drivers/pci/controller/pci-hyperv.c
>> @@ -704,8 +704,14 @@ static void hv_arch_irq_unmask(struct irq_data *data)
>>   		}
>>   	}
>>   
>> -	res = hv_do_hypercall(HVCALL_RETARGET_INTERRUPT | (var_size << 17),
>> -			      params, NULL);
>> +	if (hv_nested)
>> +		res = hv_do_nested_hypercall(HVCALL_RETARGET_INTERRUPT |
>> +					     (var_size << 17),
>> +					     params, NULL);
>> +	else
>> +		res = hv_do_hypercall(HVCALL_RETARGET_INTERRUPT |
>> +				      (var_size << 17),
>> +				      params, NULL);
>>   
>>   exit_unlock:
>>   	spin_unlock_irqrestore(&hbus->retarget_msi_interrupt_lock, flags);
>> -- 
>> 2.34.1
>>