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From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: 谢华伟(此时此刻) <huawei.xhw@alibaba-inc.com>, ferruh.yigit@intel.com
Cc: dev@dpdk.org, anatoly.burakov@intel.com,
	david.marchand@redhat.com, zhihong.wang@intel.com,
	chenbo.xia@intel.com, grive@u256.net
Subject: Re: [dpdk-dev] [PATCH v5 3/3] PCI: don't use vfio ioctl call to access PIO resource
Date: Tue, 12 Jan 2021 17:58:18 +0100
Message-ID: <e5d7e73e-58c8-4820-85f4-ee9a8e90064f@redhat.com> (raw)
In-Reply-To: <fb903a81-a032-3300-29f9-218164fe8e56@redhat.com>



On 1/12/21 10:37 AM, Maxime Coquelin wrote:
> bus/pci: ...
> 
> On 10/22/20 5:51 PM, 谢华伟(此时此刻) wrote:
>> From: "huawei.xhw" <huawei.xhw@alibaba-inc.com>
>>
>> VFIO should use the same way to map/read/write PORT IO as UIO, for
>> virtio PMD.
> 
> Please provide more details in the commit message on why the way VFIO
> works today is wrong (The cover letter is lost once applied).
> 
>> Signed-off-by: huawei.xhw <huawei.xhw@alibaba-inc.com>
> 
> Same comment about name format as on previous patches.
> 
>> ---
>>  drivers/bus/pci/linux/pci.c     | 8 ++++----
>>  drivers/bus/pci/linux/pci_uio.c | 4 +++-
>>  2 files changed, 7 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/bus/pci/linux/pci.c b/drivers/bus/pci/linux/pci.c
>> index 0dc99e9..2ed9f2b 100644
>> --- a/drivers/bus/pci/linux/pci.c
>> +++ b/drivers/bus/pci/linux/pci.c
>> @@ -687,7 +687,7 @@ int rte_pci_write_config(const struct rte_pci_device *device,
>>  #ifdef VFIO_PRESENT
>>  	case RTE_PCI_KDRV_VFIO:
>>  		if (pci_vfio_is_enabled())
>> -			ret = pci_vfio_ioport_map(dev, bar, p);
>> +			ret = pci_uio_ioport_map(dev, bar, p);
> 
> Doesn't it create a regression with regards to needed capabilities?
> My understanding is that before this patch we don't need to call iopl(),
> whereas once applied it is required, correct?

I did some testing today, and think it is not a regression with para-
virtualized Virtio devices.

Indeed, I thought it would be a regression with Legacy devices when
IOMMU is enabled and the program is run as non-root (IOMMU enabled
just to suport IOVA as VA mode). But it turns out para-virtualized
Virtio legacy device and vIOMMU enabled is not a supported configuration
by QEMU.

Note that when noiommu mode is enabled, the app needs cap_sys_rawio, so
same as iopl(). No regression in this case too.

That said, with real (non para-virtualized) Virtio device using PIO like
yours, doesn't your patch introduce a restriction for your device that
it will require cap_sys_rawio whereas it would not be needed?

Thanks,
Maxime

> Regards,
> Maxime
> 


  reply	other threads:[~2021-01-12 16:58 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-30 14:59 [dpdk-dev] [PATCH v2] pci: support both PIO and MMIO BAR for legacy virtio on x86 谢华伟(此时此刻)
2020-10-01 10:22 ` Burakov, Anatoly
2020-10-02  5:44   ` 谢华伟(此时此刻)
2020-10-09  8:36 ` [dpdk-dev] [PATCH v3] " 谢华伟(此时此刻)
2020-10-13  8:41 ` [dpdk-dev] [PATCH v4] support both PIO and MMIO bar for virtio pci device 谢华伟(此时此刻)
2020-10-13  8:41   ` [dpdk-dev] [PATCH v4] pci: support both PIO and MMIO BAR for legacy virtio on x86 谢华伟(此时此刻)
2020-10-13 12:34     ` 谢华伟(此时此刻)
2020-10-21  8:46     ` 谢华伟(此时此刻)
2020-10-21 11:49     ` Ferruh Yigit
2020-10-21 12:32       ` 谢华伟(此时此刻)
2020-10-21 17:24         ` Ferruh Yigit
2020-10-22  9:15           ` 谢华伟(此时此刻)
2020-10-22  9:44             ` Ferruh Yigit
2020-10-22  9:57               ` 谢华伟(此时此刻)
2020-10-22 15:51 ` [dpdk-dev] [PATCH v5 0/3] support both PIO and MMIO BAR for virtio PMD 谢华伟(此时此刻)
2020-10-22 15:51   ` [dpdk-dev] [PATCH v5 1/3] PCI: use PCI standard sysfs entry to get PIO address 谢华伟(此时此刻)
2021-01-12  8:07     ` Maxime Coquelin
2021-01-14 18:23       ` 谢华伟(此时此刻)
2021-01-24 15:10         ` Xueming(Steven) Li
2020-10-22 15:51   ` [dpdk-dev] [PATCH v5 2/3] PCI: support MMIO in rte_pci_ioport_map/unap/read/write 谢华伟(此时此刻)
2021-01-12  8:23     ` Maxime Coquelin
2021-01-21  6:30       ` 谢华伟(此时此刻)
2021-01-24 15:22     ` Xueming(Steven) Li
2021-01-25  3:08       ` 谢华伟(此时此刻)
2021-01-27 10:40     ` Ferruh Yigit
2021-01-27 15:34       ` 谢华伟(此时此刻)
2021-01-27 16:45         ` Ferruh Yigit
2020-10-22 15:51   ` [dpdk-dev] [PATCH v5 3/3] PCI: don't use vfio ioctl call to access PIO resource 谢华伟(此时此刻)
2021-01-12  9:37     ` Maxime Coquelin
2021-01-12 16:58       ` Maxime Coquelin [this message]
2021-01-20 14:54         ` 谢华伟(此时此刻)
2021-01-21  8:29           ` Maxime Coquelin
2021-01-21 14:57             ` 谢华伟(此时此刻)
2021-01-21 15:00               ` 谢华伟(此时此刻)
2021-01-21 15:38               ` Maxime Coquelin
2021-01-22  7:25                 ` 谢华伟(此时此刻)
2021-01-26 10:44                   ` Maxime Coquelin
2021-01-27 10:32                     ` Ferruh Yigit
2021-01-27 12:17                       ` Maxime Coquelin
2021-01-27 14:43                       ` 谢华伟(此时此刻)
2021-01-27 16:45                         ` Ferruh Yigit
2021-01-28 13:43                           ` 谢华伟(此时此刻)
2021-01-26 12:30                   ` 谢华伟(此时此刻)
2021-01-26 12:35                     ` Maxime Coquelin
2021-01-26 14:24                       ` 谢华伟(此时此刻)
2020-10-27  8:50   ` [dpdk-dev] [PATCH v5 0/3] support both PIO and MMIO BAR for virtio PMD 谢华伟(此时此刻)
2020-10-28  3:48     ` 谢华伟(此时此刻)
2020-11-02 11:56   ` 谢华伟(此时此刻)
2020-11-10 12:35   ` 谢华伟(此时此刻)
2020-11-10 12:42     ` David Marchand
2020-11-12 13:35       ` 谢华伟(此时此刻)
2020-12-14 14:24       ` 谢华伟(此时此刻)
2020-12-16  7:54         ` Maxime Coquelin
2021-01-12 17:37   ` Maxime Coquelin
2021-01-14 18:19     ` 谢华伟(此时此刻)
2021-01-21  4:12     ` 谢华伟(此时此刻)
2021-01-21  8:47       ` Maxime Coquelin
2021-01-21 13:51         ` 谢华伟(此时此刻)

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