From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46959) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WvPwX-00039H-7i for qemu-devel@nongnu.org; Fri, 13 Jun 2014 07:46:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WvPwP-0005Da-MK for qemu-devel@nongnu.org; Fri, 13 Jun 2014 07:46:49 -0400 Received: from cantor2.suse.de ([195.135.220.15]:53976 helo=mx2.suse.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WvPwP-0005DS-AZ for qemu-devel@nongnu.org; Fri, 13 Jun 2014 07:46:41 -0400 Message-ID: <539AE49F.3000708@suse.de> Date: Fri, 13 Jun 2014 13:46:39 +0200 From: Alexander Graf MIME-Version: 1.0 References: <20140613111703.22108.14322.stgit@bahia.local> <20140613112226.22108.50811.stgit@bahia.local> In-Reply-To: <20140613112226.22108.50811.stgit@bahia.local> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v8 11/20] virtio: add endian-ambivalent support to VirtIODevice List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Greg Kurz , qemu-devel@nongnu.org Cc: Kevin Wolf , Peter Maydell , Stefan Hajnoczi , Juan Quintela , Rusty Russell , "Michael S. Tsirkin" , aneesh.kumar@linux.vnet.ibm.com, Anthony Liguori , Amit Shah , Paolo Bonzini , =?UTF-8?B?QW5kcmVhcyBGw6RyYmVy?= On 13.06.14 13:23, Greg Kurz wrote: > Some CPU families can dynamically change their endianness. This means we > can have little endian ppc or big endian arm guests for example. This has > an impact on legacy virtio data structures since they are target endian. > We hence introduce a new property to track the endianness of each virtio > device. It is reasonnably assumed that endianness won't change while the > device is in use : we hence capture the device endianness when it gets > reset. > > We migrate this property in a subsection, after the device descriptor. This > means the load code must not rely on it until it is restored. As a consequence, > the vring sanity checks had to be moved after the call to vmstate_load_state(). > We enforce paranoia by poisoning the property at the begining of virtio_load(). > > Signed-off-by: Greg Kurz > --- > > Changes since last version (virtio migration RFC): > - endianness cached at device reset time > - reworked migration support > > hw/virtio/virtio-pci.c | 8 ++-- > hw/virtio/virtio.c | 100 +++++++++++++++++++++++++++++++++++++++----- > include/hw/virtio/virtio.h | 12 ++++- > 3 files changed, 102 insertions(+), 18 deletions(-) > > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c > index 390c8d2..2ffceb8 100644 > --- a/hw/virtio/virtio-pci.c > +++ b/hw/virtio/virtio-pci.c > @@ -406,13 +406,13 @@ static uint64_t virtio_pci_config_read(void *opaque, hwaddr addr, > break; > case 2: > val = virtio_config_readw(vdev, addr); > - if (virtio_is_big_endian()) { > + if (virtio_is_big_endian(vdev)) { > val = bswap16(val); > } > break; > case 4: > val = virtio_config_readl(vdev, addr); > - if (virtio_is_big_endian()) { > + if (virtio_is_big_endian(vdev)) { > val = bswap32(val); > } > break; > @@ -440,13 +440,13 @@ static void virtio_pci_config_write(void *opaque, hwaddr addr, > virtio_config_writeb(vdev, addr, val); > break; > case 2: > - if (virtio_is_big_endian()) { > + if (virtio_is_big_endian(vdev)) { > val = bswap16(val); > } > virtio_config_writew(vdev, addr, val); > break; > case 4: > - if (virtio_is_big_endian()) { > + if (virtio_is_big_endian(vdev)) { > val = bswap32(val); > } > virtio_config_writel(vdev, addr, val); > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c > index 16b73d9..6235df8 100644 > --- a/hw/virtio/virtio.c > +++ b/hw/virtio/virtio.c > @@ -545,6 +545,24 @@ void virtio_set_status(VirtIODevice *vdev, uint8_t val) > vdev->status = val; > } > > +static void virtio_set_endian_target_default(VirtIODevice *vdev) > +{ > +#ifdef TARGET_WORDS_BIGENDIAN > + vdev->device_endian = VIRTIO_DEVICE_ENDIAN_BIG; > +#else > + vdev->device_endian = VIRTIO_DEVICE_ENDIAN_LITTLE; > +#endif > +} > + > +static void virtio_set_endian_cpu(VirtIODevice *vdev, CPUState *cpu) > +{ > + if (cpu_virtio_is_big_endian(cpu)) { > + vdev->device_endian = VIRTIO_DEVICE_ENDIAN_BIG; > + } else { > + vdev->device_endian = VIRTIO_DEVICE_ENDIAN_LITTLE; > + } > +} > + > void virtio_reset(void *opaque) > { > VirtIODevice *vdev = opaque; > @@ -552,6 +570,13 @@ void virtio_reset(void *opaque) > int i; > > virtio_set_status(vdev, 0); > + if (current_cpu) { > + /* Guest initiated reset */ > + virtio_set_endian_cpu(vdev, current_cpu); > + } else { > + /* System reset */ > + virtio_set_endian_target_default(vdev); > + } > > if (k->reset) { > k->reset(vdev); > @@ -840,6 +865,28 @@ void virtio_notify_config(VirtIODevice *vdev) > virtio_notify_vector(vdev, vdev->config_vector); > } > > +static bool virtio_device_endian_needed(void *opaque) > +{ > + VirtIODevice *vdev = opaque; > + > + assert(vdev->device_endian != VIRTIO_DEVICE_ENDIAN_UNKNOWN); > +#ifdef TARGET_WORDS_BIGENDIAN > + return vdev->device_endian == VIRTIO_DEVICE_ENDIAN_LITTLE; > +#else > + return vdev->device_endian == VIRTIO_DEVICE_ENDIAN_BIG; > +#endif if (target_words_bigendian()) { return virtio_is_big_endian(); } else { return !virtio_is_big_endian(); } Then we have one less dependency on TARGET_WORDS_BIGENDIAN which means a step towards compiling virtio once ;). Alex