From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39351) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eHoK3-0007Xx-EI for qemu-devel@nongnu.org; Thu, 23 Nov 2017 05:01:32 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eHoK0-0006Um-D7 for qemu-devel@nongnu.org; Thu, 23 Nov 2017 05:01:31 -0500 References: <1511388334-16347-1-git-send-email-pmorel@linux.vnet.ibm.com> <1511388334-16347-2-git-send-email-pmorel@linux.vnet.ibm.com> <3acc6fdb-5638-97b2-2dc7-bce34d22cd1f@redhat.com> <20171123104903.24424b40.cohuck@redhat.com> From: Thomas Huth Message-ID: Date: Thu, 23 Nov 2017 11:01:23 +0100 MIME-Version: 1.0 In-Reply-To: <20171123104903.24424b40.cohuck@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v3 1/7] s390x/pci: factor out endianess conversion List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Cornelia Huck Cc: Pierre Morel , qemu-devel@nongnu.org, borntraeger@de.ibm.com, pasic@linux.vnet.ibm.com, zyimin@linux.vnet.ibm.com, agraf@suse.de, Qemu-s390x list On 23.11.2017 10:49, Cornelia Huck wrote: > On Thu, 23 Nov 2017 09:48:41 +0100 > Thomas Huth wrote: > >> On 22.11.2017 23:05, Pierre Morel wrote: >>> There are two places where the same endianness conversion >>> is done. >>> Let's factor this out into a static function. >>> >>> Signed-off-by: Pierre Morel >>> Reviewed-by: Yi Min Zhao >>> --- >>> hw/s390x/s390-pci-inst.c | 59 +++++++++++++++++++++++++++--------------------- >>> 1 file changed, 33 insertions(+), 26 deletions(-) >>> >>> diff --git a/hw/s390x/s390-pci-inst.c b/hw/s390x/s390-pci-inst.c >>> index 8e088f3..3e1f1a0 100644 >>> --- a/hw/s390x/s390-pci-inst.c >>> +++ b/hw/s390x/s390-pci-inst.c >>> @@ -314,6 +314,36 @@ out: >>> return 0; >>> } >>> >>> +/** >>> + * Swap data contained in s390x big endian registers to little endian >>> + * PCI bars. >>> + * >>> + * @ptr: a pointer to a uint64_t data field >>> + * @len: the length of the valid data, must be 1,2,4 or 8 >>> + */ >>> +static int zpci_endian_swap(uint64_t *ptr, uint8_t len) >>> +{ >>> + uint64_t data = *ptr; >>> + >>> + switch (len) { >>> + case 1: >>> + break; >>> + case 2: >>> + data = bswap16(data); >>> + break; >>> + case 4: >>> + data = bswap32(data); >>> + break; >>> + case 8: >>> + data = bswap64(data); >>> + break; >>> + default: >>> + return -EINVAL; >>> + } >>> + *ptr = data; >>> + return 0; >>> +} >> >> While you're at it, I think that should rather be leXX_to_cpu() instead >> of bswapXX() here, > > I don't think that's correct, as this is supposed to swap BE registers > to LE PCI bars. Yes, but for the CPU emulation, the registers are stored in the host's endianness in the CPUS390XState structure. Or why do we byte-swap them again with cpu_to_be64() during s390_store_status(), for example? Thomas