From: Bjorn Helgaas <bhelgaas@google.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Bjorn Helgaas <helgaas@kernel.org>,
Yongji Xie <elohimes@gmail.com>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
Gavin Shan <gwshan@linux.vnet.ibm.com>,
Alexey Kardashevskiy <aik@ozlabs.ru>,
Michael Ellerman <mpe@ellerman.id.au>,
"paulus@samba.org" <paulus@samba.org>,
Li Zhong <zhong@linux.vnet.ibm.com>
Subject: Re: [PATCH v10 3/4] powerpc/powernv: Override pcibios_default_alignment() to force PCI devices to be page aligned
Date: Mon, 17 Apr 2017 10:51:09 -0500 [thread overview]
Message-ID: <CAErSpo6X0JwjqfPN3A5XGqKTdsXw3crTOvn9n+jvN86XHgriVw@mail.gmail.com> (raw)
In-Reply-To: <1492293974.25766.30.camel@kernel.crashing.org>
On Sat, Apr 15, 2017 at 5:06 PM, Benjamin Herrenschmidt
<benh@kernel.crashing.org> wrote:
> On Sat, 2017-04-15 at 11:36 -0500, Bjorn Helgaas wrote:
>> > I agree in principle. I'm surprised that PowerPC is the only one
>> > interested here though, what about other platforms who want to use
>> > KVM and PCI pass-through and use Linux to assign BARs ?
>>
>> If I understand correctly, the problem is with BARs smaller than a
>> page, and this happens more on PowerPC because larger page sizes are
>> more common there.
>
> Yes, it happens "more". That doesn't mean it doesn't happen at all on
> others :-) Anyway, I'm not objecting, just surprised.
Yeah, I agree. Maybe the devices interesting for pass-through tend to
have BARs of least 4KB? Those would never be a problem on x86. But I
have absolutely no data either way.
next prev parent reply other threads:[~2017-04-17 15:51 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-10 11:58 [PATCH v10 0/4] PCI: Introduce a way to enforce all MMIO BARs not to share PAGE_SIZE Yongji Xie
2017-04-10 11:58 ` [PATCH v10 1/4] PCI: A fix for caculating bridge window's size and alignment Yongji Xie
2017-04-10 11:58 ` [PATCH v10 2/4] PCI: Add pcibios_default_alignment() for arch-specific alignment control Yongji Xie
2017-04-10 11:58 ` [PATCH v10 3/4] powerpc/powernv: Override pcibios_default_alignment() to force PCI devices to be page aligned Yongji Xie
2017-04-14 15:58 ` Bjorn Helgaas
2017-04-14 21:52 ` Benjamin Herrenschmidt
2017-04-15 16:36 ` Bjorn Helgaas
2017-04-15 22:06 ` Benjamin Herrenschmidt
2017-04-17 15:51 ` Bjorn Helgaas [this message]
2017-04-10 11:58 ` [PATCH v10 4/4] PCI: Don't extend device's size when using default alignment for all devices Yongji Xie
2017-04-14 22:54 ` Bjorn Helgaas
2017-04-17 6:27 ` Yongji Xie
2017-04-17 20:33 ` Bjorn Helgaas
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