From mboxrd@z Thu Jan 1 00:00:00 1970 From: yang.shi@linaro.org (Shi, Yang) Date: Fri, 15 Apr 2016 10:53:47 -0700 Subject: [PATCH] iommu/arm-smmu: Fix stream-match conflict with IOMMU_DOMAIN_DMA In-Reply-To: <5711043C.5040308@linaro.org> References: <1459527597-10740-1-git-send-email-will.deacon@arm.com> <5711043C.5040308@linaro.org> Message-ID: <57112AAB.6050209@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 4/15/2016 8:09 AM, Eric Auger wrote: > Hi Will, > On 04/01/2016 06:19 PM, Will Deacon wrote: >> Commit cbf8277ef456 ("iommu/arm-smmu: Treat IOMMU_DOMAIN_DMA as bypass >> for now") ignores requests to attach a device to the default domain >> since, without IOMMU-basked DMA ops available everywhere, the default >> domain will just lead to unexpected transaction faults being reported. >> >> Unfortunately, the way this was implemented on SMMUv2 causes a >> regression with VFIO PCI device passthrough under KVM on AMD Seattle. >> On this system, the host controller device is associated with both a >> pci_dev *and* a platform_device, and can therefore end up with duplicate >> SMR entries, resulting in a stream-match conflict at runtime. >> >> This patch amends the original fix so that attaching to IOMMU_DOMAIN_DMA >> is rejected even before configuring the SMRs. This restores the old >> behaviour for now, but we'll need to look at handing host controllers >> specially when we come to supporting the default domain fully. >> > Tested-by: Eric Auger Tested on my LS2085A board too. Tested-by: Yang Shi Regards, Yang > > Best Regards > > Eric >> Reported-by: Eric Auger >> Signed-off-by: Will Deacon >> --- >> drivers/iommu/arm-smmu.c | 14 ++++++++------ >> 1 file changed, 8 insertions(+), 6 deletions(-) >> >> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c >> index e933679a3266..2f186d22477f 100644 >> --- a/drivers/iommu/arm-smmu.c >> +++ b/drivers/iommu/arm-smmu.c >> @@ -1098,18 +1098,20 @@ static int arm_smmu_domain_add_master(struct arm_smmu_domain *smmu_domain, >> struct arm_smmu_device *smmu = smmu_domain->smmu; >> void __iomem *gr0_base = ARM_SMMU_GR0(smmu); >> >> - /* Devices in an IOMMU group may already be configured */ >> - ret = arm_smmu_master_configure_smrs(smmu, cfg); >> - if (ret) >> - return ret == -EEXIST ? 0 : ret; >> - >> /* >> * FIXME: This won't be needed once we have IOMMU-backed DMA ops >> - * for all devices behind the SMMU. >> + * for all devices behind the SMMU. Note that we need to take >> + * care configuring SMRs for devices both a platform_device and >> + * and a PCI device (i.e. a PCI host controller) >> */ >> if (smmu_domain->domain.type == IOMMU_DOMAIN_DMA) >> return 0; >> >> + /* Devices in an IOMMU group may already be configured */ >> + ret = arm_smmu_master_configure_smrs(smmu, cfg); >> + if (ret) >> + return ret == -EEXIST ? 0 : ret; >> + >> for (i = 0; i < cfg->num_streamids; ++i) { >> u32 idx, s2cr; >> >> > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel at lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >