From: Bjorn Helgaas <helgaas@kernel.org>
To: Yongji Xie <xyjxie@linux.vnet.ibm.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-pci@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
iommu@lists.linux-foundation.org, alex.williamson@redhat.com,
bhelgaas@google.com, aik@ozlabs.ru, benh@kernel.crashing.org,
paulus@samba.org, mpe@ellerman.id.au, joro@8bytes.org,
warrier@linux.vnet.ibm.com, zhong@linux.vnet.ibm.com,
nikunj@linux.vnet.ibm.com, eric.auger@linaro.org,
will.deacon@arm.com, gwshan@linux.vnet.ibm.com,
David.Laight@ACULAB.COM, alistair@popple.id.au,
ruscur@russell.cc
Subject: Re: [PATCH 1/5] PCI: Add a new PCI_BUS_FLAGS_MSI_REMAP flag
Date: Tue, 24 May 2016 15:55:19 -0500 [thread overview]
Message-ID: <20160524205519.GA16463@localhost> (raw)
In-Reply-To: <1461761010-5452-2-git-send-email-xyjxie@linux.vnet.ibm.com>
On Wed, Apr 27, 2016 at 08:43:26PM +0800, Yongji Xie wrote:
> We introduce a new pci_bus_flags, PCI_BUS_FLAGS_MSI_REMAP
> which indicates all devices on the bus are protected by the
> hardware which supports IRQ remapping(intel naming).
This changelog is ambiguous. It's possible that there is hardware
that *supports* IRQ remapping, but does not actually *do* IRQ
remapping. For example, an IRQ remapping capability may be present
but not enabled.
I think your intent is to set this flag only when MSI remapping is
actually *enabled* for all devices on the bus.
I'd also like to know exactly what protection is implied by
PCI_BUS_FLAGS_MSI_REMAP and IOMMU_CAP_INTR_REMAP. I guess it means a
device can only generate MSIs to a certain set of CPUs? I assume the
remapping hardware only checks the target address, not the data being
written?
> This flag will be used to know whether it's safe to expose
> MSI-X tables of PCI BARs to userspace. Because the capability
> of IRQ remapping can guarantee the PCI device cannot trigger
> MSIs that correspond to interrupt IDs of other devices.
>
> There is a existing flag for this in the IOMMU space:
>
> enum iommu_cap {
> IOMMU_CAP_CACHE_COHERENCY,
> ---> IOMMU_CAP_INTR_REMAP,
> IOMMU_CAP_NOEXEC,
> };
>
> and Eric also posted a patchset [1] to abstract this
> capability on MSI controller side for ARM. But it would
> make sense to have a more common flag like
> PCI_BUS_FLAGS_MSI_REMAP in this patch so that we can use
> a universal flag to test this capability on PCI side for
> different archs.
>
> [1] http://www.spinics.net/lists/kvm/msg130256.html
>
> Signed-off-by: Yongji Xie <xyjxie@linux.vnet.ibm.com>
> ---
> include/linux/pci.h | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 27df4a6..d619228 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -193,6 +193,7 @@ typedef unsigned short __bitwise pci_bus_flags_t;
> enum pci_bus_flags {
> PCI_BUS_FLAGS_NO_MSI = (__force pci_bus_flags_t) 1,
> PCI_BUS_FLAGS_NO_MMRBC = (__force pci_bus_flags_t) 2,
> + PCI_BUS_FLAGS_MSI_REMAP = (__force pci_bus_flags_t) 4,
> };
>
> /* These values come from the PCI Express Spec */
> --
> 1.7.9.5
>
next prev parent reply other threads:[~2016-05-24 20:55 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-27 12:43 [PATCH 0/5] vfio-pci: Add support for mmapping MSI-X table Yongji Xie
2016-04-27 12:43 ` [PATCH 1/5] PCI: Add a new PCI_BUS_FLAGS_MSI_REMAP flag Yongji Xie
2016-05-24 20:55 ` Bjorn Helgaas [this message]
2016-05-25 5:46 ` Yongji Xie
2016-04-27 12:43 ` [PATCH 2/5] iommu: Set PCI_BUS_FLAGS_MSI_REMAP if IOMMU have capability of IRQ remapping Yongji Xie
2016-05-24 21:11 ` Bjorn Helgaas
2016-05-25 5:54 ` Yongji Xie
[not found] ` <201605250554.u4P5sRqv014439@mx0a-001b2d01.pphosted.com>
2016-05-26 3:48 ` Bjorn Helgaas
2016-04-27 12:43 ` [PATCH 3/5] PCI: Set PCI_BUS_FLAGS_MSI_REMAP if MSI controller supports " Yongji Xie
2016-05-24 21:04 ` Bjorn Helgaas
2016-05-25 5:48 ` Yongji Xie
2016-04-27 12:43 ` [PATCH 4/5] pci-ioda: Set PCI_BUS_FLAGS_MSI_REMAP for IODA host bridge Yongji Xie
2016-05-06 6:34 ` Alexey Kardashevskiy
2016-04-27 12:43 ` [PATCH 5/5] vfio-pci: Allow to mmap MSI-X table if interrupt remapping is supported Yongji Xie
2016-05-03 5:34 ` Tian, Kevin
2016-05-03 6:08 ` Yongji Xie
2016-05-03 6:22 ` Tian, Kevin
2016-05-03 7:34 ` Yongji Xie
2016-05-05 9:36 ` Tian, Kevin
2016-05-05 9:54 ` David Laight
2016-05-05 11:42 ` Yongji Xie
2016-05-05 12:15 ` Tian, Kevin
2016-05-05 13:28 ` Yongji Xie
2016-05-05 15:05 ` Alex Williamson
2016-05-06 6:35 ` Alexey Kardashevskiy
2016-05-06 16:54 ` Alex Williamson
2016-05-11 6:29 ` Tian, Kevin
2016-05-11 15:53 ` Alex Williamson
2016-05-12 1:19 ` Tian, Kevin
2016-05-12 2:20 ` Alex Williamson
2016-05-12 4:53 ` Tian, Kevin
2016-05-12 17:47 ` Alex Williamson
2016-05-13 2:33 ` Tian, Kevin
2016-05-13 5:32 ` Alex Williamson
2016-05-13 6:50 ` Tian, Kevin
2016-05-13 16:42 ` Alex Williamson
2016-05-13 9:16 ` David Laight
2016-05-13 2:36 ` Tian, Kevin
2016-05-05 11:44 ` Yongji Xie
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