[PATCH v10 3/4] powerpc/powernv: Override pcibios_default_alignment() to force PCI devices to be page aligned

From: Yongji Xie <elohimes@gmail.com>
To: bhelgaas@google.com
Cc: linux-pci@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	alex.williamson@redhat.com, gwshan@linux.vnet.ibm.com,
	aik@ozlabs.ru, benh@kernel.crashing.org, mpe@ellerman.id.au,
	paulus@samba.org, zhong@linux.vnet.ibm.com
Subject: [PATCH v10 3/4] powerpc/powernv: Override pcibios_default_alignment() to force PCI devices to be page aligned
Date: Mon, 10 Apr 2017 19:58:13 +0800	[thread overview]
Message-ID: <1491825494-19331-4-git-send-email-elohimes@gmail.com> (raw)
In-Reply-To: <1491825494-19331-1-git-send-email-elohimes@gmail.com>

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.

Signed-off-by: Yongji Xie <elohimes@gmail.com>
---
 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
