| Message ID | 20201217080802.29023-1-peng.fan@oss.nxp.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: Kconfig: select ZONE_DMA | expand |
Hi Peng, sorry for the inconvenience, this is most probably related to these changes: https://lore.kernel.org/linux-arm-kernel/20201119175400.9995-1-nsaenzjulienne@suse.de/ On Thu, 2020-12-17 at 16:08 +0800, Peng Fan (OSS) wrote: > From: Peng Fan <peng.fan@nxp.com> > > ZONE_DMA should not be disabled, otherwise arm64_dma_phys_limit is > left uninitialized and cause swiotlb have IO TLB above 4GB which > might crash some platforms > > Signed-off-by: Peng Fan <peng.fan@nxp.com> > --- > > Not sure whether need to address code to initialize the variables or > force select ZONE_DMA What is the cause for the swiotlb related crashes? I assume it's DMA into an address too high for the bus, but it might be something else. I figure you have a setup with ZONE_DMA32, ZONE_NORMAL and !ZONE_DMA. First of all, I'd suggest you try arm64's defaults (all zones enabled), the series I mention above should fix most of the issues we've had with ZONE_DMA/ZONE_DMA32 in the past. We now parse DT/ACPI and only create two distinct DMA zones if really needed. Otherwise ZONE_DMA spans the whole 32 bit address space. That said, IMO we're not doing the right thing in the !ZONE_DMA && ZONE_DMA32 case, and this should fix it (I didn't test it): - #define ARCH_LOW_ADDRESS_LIMIT (arm64_dma_phys_limit - 1) + #define ARCH_LOW_ADDRESS_LIMIT (arm64_dma_phys_limit ? : arm64_dma32_phys_limit) Regards, Nicolas
On Thu, Dec 17, 2020 at 09:44:31AM +0100, Nicolas Saenz Julienne wrote: > On Thu, 2020-12-17 at 16:08 +0800, Peng Fan (OSS) wrote: > > From: Peng Fan <peng.fan@nxp.com> > > > > ZONE_DMA should not be disabled, otherwise arm64_dma_phys_limit is > > left uninitialized and cause swiotlb have IO TLB above 4GB which > > might crash some platforms Actually, arm64_dma_phys_limit would be zero-initialised. The ARCH_LOW_ADDRESS_LIMIT becomes ~0UL, hence it covers the whole address space. > > Signed-off-by: Peng Fan <peng.fan@nxp.com> > > --- > > > > Not sure whether need to address code to initialize the variables or > > force select ZONE_DMA > > What is the cause for the swiotlb related crashes? I assume it's DMA into an > address too high for the bus, but it might be something else. I think that's the case, swiotlb is not within the low 32-bit of the address space. > I figure you have a setup with ZONE_DMA32, ZONE_NORMAL and !ZONE_DMA. > > First of all, I'd suggest you try arm64's defaults (all zones enabled), the > series I mention above should fix most of the issues we've had with > ZONE_DMA/ZONE_DMA32 in the past. We now parse DT/ACPI and only create two > distinct DMA zones if really needed. Otherwise ZONE_DMA spans the whole 32 bit > address space. > > That said, IMO we're not doing the right thing in the !ZONE_DMA && ZONE_DMA32 > case, and this should fix it (I didn't test it): > > - #define ARCH_LOW_ADDRESS_LIMIT (arm64_dma_phys_limit - 1) > + #define ARCH_LOW_ADDRESS_LIMIT (arm64_dma_phys_limit ? : arm64_dma32_phys_limit) Does this limit need to be inclusive?
On Thu, 2020-12-17 at 12:43 +0000, Catalin Marinas wrote: > On Thu, Dec 17, 2020 at 09:44:31AM +0100, Nicolas Saenz Julienne wrote: > > On Thu, 2020-12-17 at 16:08 +0800, Peng Fan (OSS) wrote: > > > From: Peng Fan <peng.fan@nxp.com> > > > > > > ZONE_DMA should not be disabled, otherwise arm64_dma_phys_limit is > > > left uninitialized and cause swiotlb have IO TLB above 4GB which > > > might crash some platforms > > Actually, arm64_dma_phys_limit would be zero-initialised. The > ARCH_LOW_ADDRESS_LIMIT becomes ~0UL, hence it covers the whole address > space. > > > > Signed-off-by: Peng Fan <peng.fan@nxp.com> > > > --- > > > > > > Not sure whether need to address code to initialize the variables or > > > force select ZONE_DMA > > > > What is the cause for the swiotlb related crashes? I assume it's DMA into an > > address too high for the bus, but it might be something else. > > I think that's the case, swiotlb is not within the low 32-bit of the > address space. > > > I figure you have a setup with ZONE_DMA32, ZONE_NORMAL and !ZONE_DMA. > > > > First of all, I'd suggest you try arm64's defaults (all zones enabled), the > > series I mention above should fix most of the issues we've had with > > ZONE_DMA/ZONE_DMA32 in the past. We now parse DT/ACPI and only create two > > distinct DMA zones if really needed. Otherwise ZONE_DMA spans the whole 32 bit > > address space. > > > > That said, IMO we're not doing the right thing in the !ZONE_DMA && ZONE_DMA32 > > case, and this should fix it (I didn't test it): > > > > - #define ARCH_LOW_ADDRESS_LIMIT (arm64_dma_phys_limit - 1) > > + #define ARCH_LOW_ADDRESS_LIMIT (arm64_dma_phys_limit ? : arm64_dma32_phys_limit) > > Does this limit need to be inclusive? Yes, I'm missing a '- 1'. I'll send a fix if there is no further push back/comments. Regards, Nicolas
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 33446269f692..377b391a41d6 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -206,6 +206,7 @@ config ARM64 select SWIOTLB select SYSCTL_EXCEPTION_TRACE select THREAD_INFO_IN_TASK + select ZONE_DMA help ARM 64-bit (AArch64) Linux support.