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[Qemu-devel] [PATCH] hw/arm/virt: mark the PCIe host controller as DMA c

From: Ard Biesheuvel
Subject: [Qemu-devel] [PATCH] hw/arm/virt: mark the PCIe host controller as DMA coherent in the DT
Date: Tue, 28 Jun 2016 19:14:50 +0200

Since QEMU performs cacheable accesses to guest memory when doing DMA
as part of the implementation of emulated PCI devices, guest drivers
should use cacheable accesses as well when running under KVM. Since this
essentially means that emulated PCI devices are DMA coherent, set the
'dma-coherent' DT property on the PCIe host controller DT node.

Signed-off-by: Ard Biesheuvel <address@hidden>
 hw/arm/virt.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index c5c125e9204a..6e098afd1fe5 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -1021,6 +1021,7 @@ static void create_pcie(const VirtBoardInfo *vbi, 
qemu_irq *pic,
     qemu_fdt_setprop_cell(vbi->fdt, nodename, "#size-cells", 2);
     qemu_fdt_setprop_cells(vbi->fdt, nodename, "bus-range", 0,
                            nr_pcie_buses - 1);
+    qemu_fdt_setprop(vbi->fdt, nodename, "dma-coherent", NULL, 0);
     if (vbi->v2m_phandle) {
         qemu_fdt_setprop_cells(vbi->fdt, nodename, "msi-parent",

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