linux-kernel - Re: [PATCH v12 5/5] iommu: Remove mode argument from iommu_set_dma

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Message-ID: <b12d96fa-9879-2739-fadd-2ebb02d75918@huawei.com>
Date:   Mon, 14 Jun 2021 18:03:03 +0100
From:   John Garry <john.garry@...wei.com>
To:     Robin Murphy <robin.murphy@....com>, <joro@...tes.org>,
        <will@...nel.org>, <dwmw2@...radead.org>,
        <baolu.lu@...ux.intel.com>
CC:     <linux-kernel@...r.kernel.org>, <iommu@...ts.linux-foundation.org>,
        <linuxarm@...wei.com>, <thunder.leizhen@...wei.com>,
        <chenxiang66@...ilicon.com>
Subject: Re: [PATCH v12 5/5] iommu: Remove mode argument from
 iommu_set_dma_strict()

On 14/06/2021 17:25, Robin Murphy wrote:
> On 2021-06-11 13:20, John Garry wrote:
>> We only ever now set strict mode enabled in iommu_set_dma_strict(), so
>> just remove the argument.
>>
>> Signed-off-by: John Garry <john.garry@...wei.com>
>> ---
>>   drivers/iommu/amd/init.c    | 2 +-
>>   drivers/iommu/intel/iommu.c | 6 +++---
>>   drivers/iommu/iommu.c       | 5 ++---
>>   include/linux/iommu.h       | 2 +-
>>   4 files changed, 7 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
>> index 0e6ae6d68f14..27e9677ec303 100644
>> --- a/drivers/iommu/amd/init.c
>> +++ b/drivers/iommu/amd/init.c
>> @@ -3098,7 +3098,7 @@ static int __init parse_amd_iommu_options(char 
>> *str)
>>   {
>>       for (; *str; ++str) {
>>           if (strncmp(str, "fullflush", 9) == 0)
>> -            iommu_set_dma_strict(true);
>> +            iommu_set_dma_strict();
>>           if (strncmp(str, "force_enable", 12) == 0)
>>               amd_iommu_force_enable = true;
>>           if (strncmp(str, "off", 3) == 0)
>> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
>> index 6763e516362c..e77b8b6e7838 100644
>> --- a/drivers/iommu/intel/iommu.c
>> +++ b/drivers/iommu/intel/iommu.c
>> @@ -452,7 +452,7 @@ static int __init intel_iommu_setup(char *str)
>>               pr_warn("intel_iommu=forcedac deprecated; use 
>> iommu.forcedac instead\n");
>>               iommu_dma_forcedac = true;
>>           } else if (!strncmp(str, "strict", 6)) {
>> -            iommu_set_dma_strict(true);
>> +            iommu_set_dma_strict();
>>           } else if (!strncmp(str, "sp_off", 6)) {
>>               pr_info("Disable supported super page\n");
>>               intel_iommu_superpage = 0;
>> @@ -4392,7 +4392,7 @@ int __init intel_iommu_init(void)
>>            */
>>           if (cap_caching_mode(iommu->cap)) {
>>               pr_warn("IOMMU batching disallowed due to 
>> virtualization\n");
>> -            iommu_set_dma_strict(true);
>> +            iommu_set_dma_strict();
>>           }
>>           iommu_device_sysfs_add(&iommu->iommu, NULL,
>>                          intel_iommu_groups,
>> @@ -5663,7 +5663,7 @@ static void quirk_calpella_no_shadow_gtt(struct 
>> pci_dev *dev)
>>       } else if (dmar_map_gfx) {
>>           /* we have to ensure the gfx device is idle before we flush */
>>           pci_info(dev, "Disabling batched IOTLB flush on Ironlake\n");
>> -        iommu_set_dma_strict(true);
>> +        iommu_set_dma_strict();
>>       }
>>   }
>>   DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0040, 
>> quirk_calpella_no_shadow_gtt);
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index ccbd5d4c1a50..146cb71c7441 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -350,10 +350,9 @@ static int __init iommu_dma_setup(char *str)
>>   }
>>   early_param("iommu.strict", iommu_dma_setup);
>> -void iommu_set_dma_strict(bool strict)
>> +void iommu_set_dma_strict(void)
>>   {
>> -    if (strict || !(iommu_cmd_line & IOMMU_CMD_LINE_STRICT))
> 
> We shouldn't need to keep IOMMU_CMD_LINE_STRICT at all now, since it was 
> only to prevent a driver's "default lazy" setting passed in here from 
> downgrading an explicitly-set strict mode.
> 
> With that cleaned up too,
> 

Patch 1/5 mentions whether the invalidation policy comes from the 
cmdline - similar to the default domain type print - so I was going to 
keep that.

And then maybe we should also set it from the deprecated x86 
driver-specific params.

But if you think that there is not much value in this additional info, 
then I can just drop it.

Cheers,
John