From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3w4Wcc0VRszDq8M for ; Sat, 15 Apr 2017 07:53:19 +1000 (AEST) Message-ID: <1492206774.25766.14.camel@kernel.crashing.org> Subject: Re: [PATCH v10 3/4] powerpc/powernv: Override pcibios_default_alignment() to force PCI devices to be page aligned From: Benjamin Herrenschmidt To: Bjorn Helgaas , Yongji Xie Cc: bhelgaas@google.com, linux-pci@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, alex.williamson@redhat.com, gwshan@linux.vnet.ibm.com, aik@ozlabs.ru, mpe@ellerman.id.au, paulus@samba.org, zhong@linux.vnet.ibm.com Date: Sat, 15 Apr 2017 07:52:54 +1000 In-Reply-To: <20170414155849.GB5864@bhelgaas-glaptop.roam.corp.google.com> References: <1491825494-19331-1-git-send-email-elohimes@gmail.com> <1491825494-19331-4-git-send-email-elohimes@gmail.com> <20170414155849.GB5864@bhelgaas-glaptop.roam.corp.google.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, 2017-04-14 at 10:58 -0500, Bjorn Helgaas wrote: > On Mon, Apr 10, 2017 at 07:58:13PM +0800, Yongji Xie wrote: > > This overrides pcibios_default_alignment() to set default alignment > > to PAGE_SIZE for all PCI devices on PowerNV platform. Thus sub-page > > BARs would not share a page and could be mapped into guest when > > VFIO > > passthrough them. > > Thanks for doing this.  This looks like a reasonable strategy to me, > but it would be good to get a powerpc ack for it. 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 ? Cheers, Ben. > > Signed-off-by: Yongji Xie > > --- > >  arch/powerpc/include/asm/machdep.h        |    2 ++ > >  arch/powerpc/kernel/pci-common.c          |    8 ++++++++ > >  arch/powerpc/platforms/powernv/pci-ioda.c |    7 +++++++ > >  3 files changed, 17 insertions(+) > > > > diff --git a/arch/powerpc/include/asm/machdep.h > > b/arch/powerpc/include/asm/machdep.h > > index 5011b69..a82c192 100644 > > --- a/arch/powerpc/include/asm/machdep.h > > +++ b/arch/powerpc/include/asm/machdep.h > > @@ -173,6 +173,8 @@ struct machdep_calls { > >   /* Called after scan and before resource survey */ > >   void (*pcibios_fixup_phb)(struct pci_controller *hose); > >   > > + resource_size_t (*pcibios_default_alignment)(struct > > pci_dev *); > > + > >  #ifdef CONFIG_PCI_IOV > >   void (*pcibios_fixup_sriov)(struct pci_dev *pdev); > >   resource_size_t (*pcibios_iov_resource_alignment)(struct > > pci_dev *, int resno); > > diff --git a/arch/powerpc/kernel/pci-common.c > > b/arch/powerpc/kernel/pci-common.c > > index ffda24a..ceda574 100644 > > --- a/arch/powerpc/kernel/pci-common.c > > +++ b/arch/powerpc/kernel/pci-common.c > > @@ -233,6 +233,14 @@ void pcibios_reset_secondary_bus(struct > > pci_dev *dev) > >   pci_reset_secondary_bus(dev); > >  } > >   > > +resource_size_t pcibios_default_alignment(struct pci_dev *pdev) > > +{ > > + if (ppc_md.pcibios_default_alignment) > > + return ppc_md.pcibios_default_alignment(pdev); > > + > > + return 0; > > +} > > + > >  #ifdef CONFIG_PCI_IOV > >  resource_size_t pcibios_iov_resource_alignment(struct pci_dev > > *pdev, int resno) > >  { > > diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c > > b/arch/powerpc/platforms/powernv/pci-ioda.c > > index e367382..354c852 100644 > > --- a/arch/powerpc/platforms/powernv/pci-ioda.c > > +++ b/arch/powerpc/platforms/powernv/pci-ioda.c > > @@ -3297,6 +3297,11 @@ static void pnv_pci_setup_bridge(struct > > pci_bus *bus, unsigned long type) > >   } > >  } > >   > > +static resource_size_t pnv_pci_default_alignment(struct pci_dev > > *pdev) > > +{ > > + return PAGE_SIZE; > > +} > > + > >  #ifdef CONFIG_PCI_IOV > >  static resource_size_t pnv_pci_iov_resource_alignment(struct > > pci_dev *pdev, > >         int resno) > > @@ -3830,6 +3835,8 @@ static void __init > > pnv_pci_init_ioda_phb(struct device_node *np, > >   hose->controller_ops = > > pnv_pci_ioda_controller_ops; > >   } > >   > > + ppc_md.pcibios_default_alignment = > > pnv_pci_default_alignment; > > + > >  #ifdef CONFIG_PCI_IOV > >   ppc_md.pcibios_fixup_sriov = > > pnv_pci_ioda_fixup_iov_resources; > >   ppc_md.pcibios_iov_resource_alignment = > > pnv_pci_iov_resource_alignment; > > --  > > 1.7.9.5 > >