Hi Will,
On Thu, May 21, 2020 at 2:53 PM Will Deacon <[email protected]> wrote: > > On Tue, May 19, 2020 at 08:24:21AM +0530, Prabhakar Kushwaha wrote: > > On Mon, May 18, 2020 at 9:25 PM Will Deacon <[email protected]> wrote: > > > On Mon, May 11, 2020 at 07:46:06PM -0700, Prabhakar Kushwaha wrote: > > > > @@ -3272,6 +3281,23 @@ static int arm_smmu_init_l1_strtab(struct > > > > arm_smmu_device *smmu) > > > > return 0; > > > > } > > > > > > > > +static void arm_smmu_copy_table(struct arm_smmu_device *smmu, > > > > + struct arm_smmu_strtab_cfg *cfg, u32 size) > > > > +{ > > > > + struct arm_smmu_strtab_cfg rdcfg; > > > > + > > > > + rdcfg.strtab_dma = readq_relaxed(smmu->base + > > > > ARM_SMMU_STRTAB_BASE); > > > > + rdcfg.strtab_base_cfg = readq_relaxed(smmu->base > > > > + + ARM_SMMU_STRTAB_BASE_CFG); > > > > + > > > > + rdcfg.strtab_dma &= STRTAB_BASE_ADDR_MASK; > > > > + rdcfg.strtab = memremap(rdcfg.strtab_dma, size, MEMREMAP_WB); > > > > + > > > > + memcpy_fromio(cfg->strtab, rdcfg.strtab, size); > > > > + > > > > this need a fix. It should be memcpy. > > > > > > + cfg->strtab_base_cfg = rdcfg.strtab_base_cfg; > > > > > > Sorry, but this is unacceptable. These things were allocated by the DMA > > > API > > > so you can't just memcpy them around and hope for the best. > > > > > > > I was referring copy_context_table() in drivers/iommu/intel-iommu.c. > > here i see usage of memremap and memcpy to copy older iommu table. > > did I take wrong reference? > > > > What kind of issue you are foreseeing in using memcpy(). May be we can > > try to find a solution. > > Well the thing might not be cache-coherent to start with... > Thanks for telling possible issue area. Let me try to explain why this should not be an issue. kdump kernel runs from reserved memory space defined during the boot of first kernel. kdump does not touch memory of the previous kernel. So no page has been created in kdump kernel and there should not be any data/attribute/coherency issue from MMU point of view . During SMMU probe functions, dmem_alloc_coherent() will be used allocate new memory (part of existing flow). This patch copy STE or first level descriptor to *this* memory, after mapping physical address using memremap(). It just copy everything so there should not be any issue related to attribute/content. Yes, copying done after mapping it as MEMREMAP_WB. if you want I can use it as MEMREMAP_WT In both scenario and also considering intel driver is doing similar things. I feel there should not be an issue. Please let me know if you have any other view to solve this problem. I will be more than happy to explore it. thanks --pk _______________________________________________ kexec mailing list [email protected] http://lists.infradead.org/mailman/listinfo/kexec
