From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36186) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZAD4f-0001cx-Im for qemu-devel@nongnu.org; Wed, 01 Jul 2015 04:08:54 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZAD4c-0003hE-7r for qemu-devel@nongnu.org; Wed, 01 Jul 2015 04:08:53 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37991) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZAD4c-0003h9-2T for qemu-devel@nongnu.org; Wed, 01 Jul 2015 04:08:50 -0400 Date: Wed, 1 Jul 2015 10:08:45 +0200 From: "Michael S. Tsirkin" Message-ID: <20150701100623-mutt-send-email-mst@redhat.com> References: <1435653553-7728-1-git-send-email-kraxel@redhat.com> <1435653553-7728-3-git-send-email-kraxel@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1435653553-7728-3-git-send-email-kraxel@redhat.com> Subject: Re: [Qemu-devel] [PATCH v2 02/22] virtio: run drivers in 32bit mode List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gerd Hoffmann Cc: seabios@seabios.org, qemu-devel@nongnu.org On Tue, Jun 30, 2015 at 10:38:53AM +0200, Gerd Hoffmann wrote: > virtio version 1.0 registers can (and actually do in the qemu > implementation) live in mmio space. So we must run the blk and > scsi virtio drivers in 32bit mode, otherwise we can't access them. > > This also allows to drop a bunch of GET_LOWFLAT calls from the virtio > code in the following patches. > > Signed-off-by: Gerd Hoffmann Is there an advantage to running them in a 16 bit mode? If yes - it's actually possible to access virtio in 16 bit mode because all virtio devices have a special capability which maps memory into pci config space. So you can poke memory (slowly) through the cf8/cfc registers. It's missing in QEMU but that's a clear spec violation: spec says it's mandatory. I'll code it up and send an RFC shortly. > --- > src/block.c | 8 +++++--- > src/hw/virtio-blk.c | 2 +- > 2 files changed, 6 insertions(+), 4 deletions(-) > > diff --git a/src/block.c b/src/block.c > index 3f7ecb1..a9b9851 100644 > --- a/src/block.c > +++ b/src/block.c > @@ -503,8 +503,10 @@ process_op(struct disk_op_s *op) > case DTYPE_CDEMU: > ret = process_cdemu_op(op); > break; > - case DTYPE_VIRTIO_BLK: > - ret = process_virtio_blk_op(op); > + case DTYPE_VIRTIO_BLK: ; > + extern void _cfunc32flat_process_virtio_blk_op(void); > + ret = call32(_cfunc32flat_process_virtio_blk_op > + , (u32)MAKE_FLATPTR(GET_SEG(SS), op), DISK_RET_EPARAM); > break; > case DTYPE_AHCI: ; > extern void _cfunc32flat_process_ahci_op(void); > @@ -526,7 +528,6 @@ process_op(struct disk_op_s *op) > break; > case DTYPE_USB: > case DTYPE_UAS: > - case DTYPE_VIRTIO_SCSI: > case DTYPE_LSI_SCSI: > case DTYPE_ESP_SCSI: > case DTYPE_MEGASAS: > @@ -534,6 +535,7 @@ process_op(struct disk_op_s *op) > break; > case DTYPE_USB_32: > case DTYPE_UAS_32: > + case DTYPE_VIRTIO_SCSI: > case DTYPE_PVSCSI: ; > extern void _cfunc32flat_scsi_process_op(void); > ret = call32(_cfunc32flat_scsi_process_op > diff --git a/src/hw/virtio-blk.c b/src/hw/virtio-blk.c > index e2dbd3c..15ac171 100644 > --- a/src/hw/virtio-blk.c > +++ b/src/hw/virtio-blk.c > @@ -77,7 +77,7 @@ virtio_blk_op(struct disk_op_s *op, int write) > return status == VIRTIO_BLK_S_OK ? DISK_RET_SUCCESS : DISK_RET_EBADTRACK; > } > > -int > +int VISIBLE32FLAT > process_virtio_blk_op(struct disk_op_s *op) > { > if (! CONFIG_VIRTIO_BLK) > -- > 1.8.3.1