hw/arm/virt: mark the PCIe host controller as DMA coherent in the DT

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.

This brings the DT description into line with the ACPI description,
which already marks the PCI bridge as cache coherent (see commit
bc64b96c984abf).

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Message-id: 1467134090-5099-1-git-send-email-ard.biesheuvel@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index c5c125e9204a0d752717b3ef04b07b34d7778462..6e098afd1fe5b6ffe2dcfbc0f4cb1506739e6655 100644 (file)
--- 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",