Hi Guo Hui,

Thanks a lot for this patch, I got some comments inline.

On 2021/8/12 20:30, Guo Hui wrote:

uniontech inclusion category: bugfix bugzilla: NA CVE: NA

Due to a problem with the IOMMU hardware of Phytium S2500/FT-2500, running the following commands on a Phytium S2500/FT-2500 machine will cause the system to hang "dd if=/dev/zero of=tmp.img bs=1M count=409600" and "I/O error" will be printed in the console.

This patch can solve the problem on Phytium S2500/FT-2500 by passthrough IOMMU.After installing the kernel using this patch, use the following command to check the parameter "iommu.passthrough=on": "cat /proc/cmdline"

I don't think it's a good solution, if we add iommu.passthrough=off or iommu=nopt in boot cmdline, will this be overlapped or replaced?

Signed-off-by: Guo Hui guohui@uniontech.com

arch/arm64/include/asm/cputype.h | 4 ++++ init/main.c | 16 ++++++++++++++++ 2 files changed, 20 insertions(+)

diff --git a/arch/arm64/include/asm/cputype.h b/arch/arm64/include/asm/cputype.h index f33947af79d9..32687e4316fb 100644 --- a/arch/arm64/include/asm/cputype.h +++ b/arch/arm64/include/asm/cputype.h @@ -85,6 +85,8 @@

#define APM_CPU_PART_POTENZA 0x000

+#define PHYTIUM_CPU_PART_2500 0X663

X -> x

• #define CAVIUM_CPU_PART_THUNDERX 0x0A1 #define CAVIUM_CPU_PART_THUNDERX_81XX 0x0A2 #define CAVIUM_CPU_PART_THUNDERX_83XX 0x0A3

@@ -123,6 +125,8 @@ #define MIDR_NVIDIA_CARMEL MIDR_CPU_MODEL(ARM_CPU_IMP_NVIDIA, NVIDIA_CPU_PART_CARMEL) #define MIDR_HISI_TSV110 MIDR_CPU_MODEL(ARM_CPU_IMP_HISI, HISI_CPU_PART_TSV110) #define MIDR_HISI_TSV200 MIDR_CPU_MODEL(ARM_CPU_IMP_HISI, HISI_CPU_PART_TSV200) +#define MIDR_FT_2500 MIDR_CPU_MODEL(ARM_CPU_IMP_PHYTIUM, \

• 	PHYTIUM_CPU_PART_2500)
  

This can be a separate path, and FT-2000 have the same issue, so we can add FT-2000 as well.

#ifndef __ASSEMBLY__

diff --git a/init/main.c b/init/main.c index c149972b46ad..388d6bd3b5b3 100644 --- a/init/main.c +++ b/init/main.c @@ -473,6 +473,22 @@ void __init parse_early_param(void) static int done __initdata; static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata;

+#ifdef CONFIG_ARM_GIC_PHYTIUM_2500

• if ((read_cpuid_id() & MIDR_CPU_MODEL_MASK) == MIDR_FT_2500) {

• char *iommu_cmd = " iommu.passthrough=on";
  

• int  iommu_cmd_len = strlen(iommu_cmd);
  

• int  boot_cmd_line_len = strlen(boot_command_line);
  

• int  last_args_len = COMMAND_LINE_SIZE - boot_cmd_line_len;
  

• if (last_args_len >= (iommu_cmd_len + 1)) {
  

• 	pr_info("FT S2500 iommu type: IOMMU_DOMAIN_IDENTITY");
  

• 	strncat(boot_command_line, iommu_cmd, iommu_cmd_len);
  

• } else {
  

• 	pr_err("FT S2500 boot_cmd_line is too long, add 'iommu.passthrough=on' failed.");
  

• }
  

• }

+#endif

As I said above, I think there is a better way to fix the issue, if it's fine to you, I can help to prepare a patch set for this issue.

Thanks Hanjun