From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiang Liu Subject: Re: [PATCH 2/2] iommu/vt-d: Work around broken RMRR firmware entries Date: Tue, 07 Oct 2014 08:59:24 +0800 Message-ID: <54333AEC.6000603@linux.intel.com> References: <1412244548-27617-1-git-send-email-joro@8bytes.org> <1412244548-27617-3-git-send-email-joro@8bytes.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1412244548-27617-3-git-send-email-joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Joerg Roedel , iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: jroedel-l3A5Bk7waGM@public.gmane.org, David Woodhouse List-Id: iommu@lists.linux-foundation.org On 2014/10/2 18:09, Joerg Roedel wrote: > From: Joerg Roedel > > The VT-d specification states that an RMRR entry in the DMAR > table needs to specify the full path to the device. This is > also how newer Linux kernels implement it. > > Unfortunatly older drivers just match for the target device > and not the full path to the device, so that BIOS vendors > implement that behavior into their BIOSes to make them work > with older Linux kernels. But those RMRR entries break on > newer Linux kernels. > > Work around this issue by adding a fall-back into the RMRR > matching code to match those old RMRR entries too. > > Signed-off-by: Joerg Roedel > --- > drivers/iommu/dmar.c | 22 +++++++++++++++++++--- > 1 file changed, 19 insertions(+), 3 deletions(-) > > diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c > index 6ba28b0..371ff33 100644 > --- a/drivers/iommu/dmar.c > +++ b/drivers/iommu/dmar.c > @@ -178,17 +178,33 @@ static bool dmar_match_pci_path(struct dmar_pci_notify_info *info, int bus, > int i; > > if (info->bus != bus) > - return false; > + goto fallback; > if (info->level != count) > - return false; > + goto fallback; > > for (i = 0; i < count; i++) { > if (path[i].device != info->path[i].device || > path[i].function != info->path[i].function) > - return false; > + goto fallback; > } > > return true; > + > +fallback: > + > + if (count != 1) > + return false; > + > + i = info->level - 1; > + if (bus == info->path[i].bus && > + path[0].device == info->path[i].device && > + path[0].function == info->path[i].function) { > + pr_info(FW_BUG "RMRR entry for device %02x:%02x.%x is broken - applying workaround\n", > + bus, path[0].device, path[0].function); > + return true; > + } > + > + return false; > } > > /* Return: > 0 if match found, 0 if no match found, < 0 if error happens */ > Hi Joerg, Thanks for fixing this:) Reviewed-by: Jiang Liu Regards! Gerry