APPLIED: [PATCH][Unstable][SRU Disco] iommu/arm-smmu-v3: Don't disable SMMU in kdump kernel
Kleber Souza
kleber.souza at canonical.com
Mon Jun 3 14:36:12 UTC 2019
On 5/13/19 8:28 PM, dann frazier wrote:
> From: Will Deacon <will.deacon at arm.com>
>
> BugLink: https://bugs.launchpad.net/bugs/1828868
>
> Disabling the SMMU when probing from within a kdump kernel so that all
> incoming transactions are terminated can prevent the core of the crashed
> kernel from being transferred off the machine if all I/O devices are
> behind the SMMU.
>
> Instead, continue to probe the SMMU after it is disabled so that we can
> reinitialise it entirely and re-attach the DMA masters as they are reset.
> Since the kdump kernel may not have drivers for all of the active DMA
> masters, we suppress fault reporting to avoid spamming the console and
> swamping the IRQ threads.
>
> Reported-by: "Leizhen (ThunderTown)" <thunder.leizhen at huawei.com>
> Tested-by: "Leizhen (ThunderTown)" <thunder.leizhen at huawei.com>
> Tested-by: Bhupesh Sharma <bhsharma at redhat.com>
> Signed-off-by: Will Deacon <will.deacon at arm.com>
> (cherry picked from commit 3f54c447df34ff9efac7809a4a80fd3208efc619)
> Signed-off-by: dann frazier <dann.frazier at canonical.com>
> ---
> drivers/iommu/arm-smmu-v3.c | 10 ++++------
> 1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
> index 0d284029dc735..e6baf509bc07d 100644
> --- a/drivers/iommu/arm-smmu-v3.c
> +++ b/drivers/iommu/arm-smmu-v3.c
> @@ -2455,13 +2455,9 @@ static int arm_smmu_device_reset(struct arm_smmu_device *smmu, bool bypass)
> /* Clear CR0 and sync (disables SMMU and queue processing) */
> reg = readl_relaxed(smmu->base + ARM_SMMU_CR0);
> if (reg & CR0_SMMUEN) {
> - if (is_kdump_kernel()) {
> - arm_smmu_update_gbpa(smmu, GBPA_ABORT, 0);
> - arm_smmu_device_disable(smmu);
> - return -EBUSY;
> - }
> -
> dev_warn(smmu->dev, "SMMU currently enabled! Resetting...\n");
> + WARN_ON(is_kdump_kernel() && !disable_bypass);
> + arm_smmu_update_gbpa(smmu, GBPA_ABORT, 0);
> }
>
> ret = arm_smmu_device_disable(smmu);
> @@ -2554,6 +2550,8 @@ static int arm_smmu_device_reset(struct arm_smmu_device *smmu, bool bypass)
> return ret;
> }
>
> + if (is_kdump_kernel())
> + enables &= ~(CR0_EVTQEN | CR0_PRIQEN);
>
> /* Enable the SMMU interface, or ensure bypass */
> if (!bypass || disable_bypass) {
>
Applied to disco/master-next branch.
Thanks,
Kleber
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