From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTP id 4B520DDDF3 for ; Thu, 11 Jan 2007 13:34:05 +1100 (EST) Subject: Re: [PATCH] Urgent: powerpc 2.6.20-rc4 dma broken on non-LPAR pseries From: Benjamin Herrenschmidt To: Linas Vepstas In-Reply-To: <20070111011629.GF6177@austin.ibm.com> References: <20070111011629.GF6177@austin.ibm.com> Content-Type: text/plain Date: Thu, 11 Jan 2007 13:31:51 +1100 Message-Id: <1168482711.22458.384.camel@localhost.localdomain> Mime-Version: 1.0 Cc: linuxppc-dev@ozlabs.org, Paul Mackerras , Anton Blanchard List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2007-01-10 at 19:16 -0600, Linas Vepstas wrote: > Paul, please review, apply and send upstream. > > I marked the subject line as urgent, as I think 2.6.20-rc4 is > broken for all pSeries non-LPAR systems. > > It appears that the iommu table address is never stored, and thus > never found, on non-lpar systems. Thus, for example, during boot: > > <7>[ 93.067916] PCI: Scanning bus 0001:41 > <7>[ 93.068542] PCI: Found 0001:41:01.0 [8086/100f] 000200 00 > <7>[ 93.068550] PCI: Calling quirk c0000000007822e0 for 0001:41:01.0 > <7>[ 93.069815] PCI: Fixups for bus 0001:41 > <4>[ 93.070167] iommu: Device 0001:41:01.0 has no iommu table > <7>[ 93.070251] PCI: Bus scan for 0001:41 returning with max=41 > > No iommu table? How can that be? Well, circa line 471 of > arch/powerpc/platforms/pseries/iommu.c we see the code: > > while (dn && PCI_DN(dn) && PCI_DN(dn)->iommu_table == NULL) > dn = dn->parent; > > and a few lines later is the surprising print statement about > the missing table. Seems that this loop ran unto the end, never > once finding a non-null PCI_DN(dn)->iommu_table. > > The problem can be found a few lines earlier: it sems that the > value of PCI_DN(dn)->iommu_table is never ever set. Thus, the > patch sets it. > > The patch was tested on a Power4 system running in full system > partition mode, which is where I saw the problem. It works; I've > not done any wider testing. Had a breif discussion on this on irc. > > Signed-off-by: Linas Vepstas Acked-by: Benjamin Herrenschmidt > ---- > arch/powerpc/platforms/pseries/iommu.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > Index: linux-2.6.20-rc4/arch/powerpc/platforms/pseries/iommu.c > =================================================================== > --- linux-2.6.20-rc4.orig/arch/powerpc/platforms/pseries/iommu.c 2007-01-10 18:38:37.000000000 -0600 > +++ linux-2.6.20-rc4/arch/powerpc/platforms/pseries/iommu.c 2007-01-10 18:40:14.000000000 -0600 > @@ -459,7 +459,8 @@ static void pci_dma_dev_setup_pSeries(st > tbl = kmalloc_node(sizeof(struct iommu_table), GFP_KERNEL, > phb->node); > iommu_table_setparms(phb, dn, tbl); > - dev->dev.archdata.dma_data = iommu_init_table(tbl, phb->node); > + PCI_DN(dn)->iommu_table = iommu_init_table(tbl, phb->node); > + dev->dev.archdata.dma_data = PCI_DN(dn)->iommu_table; > return; > } >