From ef80a708b57ddc8f605d9982bfaa0536e720ed9f Mon Sep 17 00:00:00 2001 From: Daniel Henrique Barboza Date: Fri, 17 Dec 2021 17:57:13 +0100 Subject: [PATCH] ivshmem.c: change endianness to LITTLE_ENDIAN MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The ivshmem device, as with most PCI devices, uses little endian byte order. However, the endianness of its mmio_ops is marked as DEVICE_NATIVE_ENDIAN. This presents not only the usual problems with big endian hosts but also with PowerPC little endian hosts as well, since the Power architecture in QEMU uses big endian hardware (XIVE controller, PCI Host Bridges, etc) even if the host is in little endian byte order. As it is today, the IVPosition of the device will be byte swapped when running in Power BE and LE. This can be seen by changing the existing qtest 'ivshmem-test' to run in ppc64 hosts and printing the IVPOSITION regs in test_ivshmem_server() right after the VM ids assert. For x86_64 the VM id values read are '0' and '1', for ppc64 (tested in a Power8 RHEL 7.9 BE server) and ppc64le (tested in a Power9 RHEL 8.6 LE server) the ids will be '0' and '0x1000000'. Change this device to LITTLE_ENDIAN fixes the issue for Power hosts of both endianness, and every other big-endian architecture that might use this device, without impacting x86 users. Fixes: cb06608e17f8 ("ivshmem: convert to memory API") Resolves: https://gitlab.com/qemu-project/qemu/-/issues/168 Signed-off-by: Daniel Henrique Barboza Reviewed-by: Philippe Mathieu-Daudé Message-Id: <20211124092948.335389-2-danielhb413@gmail.com> Signed-off-by: Cédric Le Goater --- hw/misc/ivshmem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c index 1ba4a98377..299837e5c1 100644 --- a/hw/misc/ivshmem.c +++ b/hw/misc/ivshmem.c @@ -243,7 +243,7 @@ static uint64_t ivshmem_io_read(void *opaque, hwaddr addr, static const MemoryRegionOps ivshmem_mmio_ops = { .read = ivshmem_io_read, .write = ivshmem_io_write, - .endianness = DEVICE_NATIVE_ENDIAN, + .endianness = DEVICE_LITTLE_ENDIAN, .impl = { .min_access_size = 4, .max_access_size = 4,