From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Goel, Sameer" Subject: Re: [PATCH] iommu/arm-smmu-v3: Set GBPA to abort all transactions Date: Wed, 11 Apr 2018 09:54:49 -0600 Message-ID: <0b58c706-e2f9-83c0-7936-f13de79e2010@codeaurora.org> References: <1522247980-31892-1-git-send-email-timur@codeaurora.org> <20180405112622.GE23485@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180405112622.GE23485@arm.com> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Will Deacon , Timur Tabi Cc: Joerg Roedel , iommu@lists.linux-foundation.org, Robin Murphy , nwatters@codeaurora.org, linux-arm-kernel@lists.infradead.org List-Id: iommu@lists.linux-foundation.org On 4/5/2018 5:26 AM, Will Deacon wrote: > On Wed, Mar 28, 2018 at 09:39:40AM -0500, Timur Tabi wrote: >> From: Sameer Goel >> >> Set SMMU_GBPA to abort all incoming translations during the SMMU reset >> when SMMUEN==0. >> >> This prevents a race condition where a stray DMA from the crashed primary >> kernel can try to access an IOVA address as an invalid PA when SMMU is >> disabled during reset in the crash kernel. >> >> Signed-off-by: Sameer Goel >> --- >> drivers/iommu/arm-smmu-v3.c | 12 ++++++++++++ >> 1 file changed, 12 insertions(+) >> >> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c >> index 3f2f1fc68b52..c04a89310c59 100644 >> --- a/drivers/iommu/arm-smmu-v3.c >> +++ b/drivers/iommu/arm-smmu-v3.c >> @@ -2458,6 +2458,18 @@ static int arm_smmu_device_reset(struct arm_smmu_device *smmu, bool bypass) >> if (reg & CR0_SMMUEN) >> dev_warn(smmu->dev, "SMMU currently enabled! Resetting...\n"); >> >> + /* >> + * Abort all incoming translations. This can happen in a kdump case >> + * where SMMU is initialized when a prior DMA is pending. Just >> + * disabling the SMMU in this case might result in writes to invalid >> + * PAs. >> + */ >> + ret = arm_smmu_update_gbpa(smmu, 1, GBPA_ABORT); >> + if (ret) { >> + dev_err(smmu->dev, "GBPA not responding to update\n"); >> + return ret; >> + } > > This needs to be predicated on the disable_bypass option, otherwise I think > it will cause regressions for systems that rely on passthrough. Ok, I'll make the change. > > Will > -- Qualcomm Datacenter Technologies as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.