From: Prasad J Pandit <p...@fedoraproject.org> Add pcie-msi mmio read method to avoid NULL pointer dereference issue.
Reported-by: Lei Sun <slei.cas...@gmail.com> Reviewed-by: Li Qiang <liq...@gmail.com> Reviewed-by: Peter Maydell <peter.mayd...@linaro.org> Signed-off-by: Prasad J Pandit <p...@fedoraproject.org> --- hw/pci-host/designware.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) Update v4: add explanatory comment and Reviewed-by tag -> https://lists.nongnu.org/archive/html/qemu-devel/2020-07/msg05315.html diff --git a/hw/pci-host/designware.c b/hw/pci-host/designware.c index 8492c18991..db036aac71 100644 --- a/hw/pci-host/designware.c +++ b/hw/pci-host/designware.c @@ -21,6 +21,7 @@ #include "qemu/osdep.h" #include "qapi/error.h" #include "qemu/module.h" +#include "qemu/log.h" #include "hw/pci/msi.h" #include "hw/pci/pci_bridge.h" #include "hw/pci/pci_host.h" @@ -63,6 +64,23 @@ designware_pcie_root_to_host(DesignwarePCIERoot *root) return DESIGNWARE_PCIE_HOST(bus->parent); } +static uint64_t designware_pcie_root_msi_read(void *opaque, hwaddr addr, + unsigned size) +{ + /* + * Attempts to read from the MSI address are undefined in + * the PCI specifications. For this hardware, the datasheet + * specifies that a read from the magic address is simply not + * intercepted by the MSI controller, and will go out to the + * AHB/AXI bus like any other PCI-device-initiated DMA read. + * This is not trivial to implement in QEMU, so since + * well-behaved guests won't ever ask a PCI device to DMA from + * this address we just log the missing functionality. + */ + qemu_log_mask(LOG_UNIMP, "%s not implemented\n", __func__); + return 0; +} + static void designware_pcie_root_msi_write(void *opaque, hwaddr addr, uint64_t val, unsigned len) { @@ -77,6 +95,7 @@ static void designware_pcie_root_msi_write(void *opaque, hwaddr addr, } static const MemoryRegionOps designware_pci_host_msi_ops = { + .read = designware_pcie_root_msi_read, .write = designware_pcie_root_msi_write, .endianness = DEVICE_LITTLE_ENDIAN, .valid = { -- 2.26.2
