Re: [PATCH 1/7] iommu/vt-d: Support size of the register set in DRHD

["Liang, Kan" <kan.liang@linux.intel.com>]

On 2023-01-12 7:42 a.m., Baolu Lu wrote:
> On 2023/1/12 4:24, kan.liang@linux.intel.com wrote:
>> From: Kan Liang <kan.liang@linux.intel.com>
>>
>> A new field, which indicates the size of the remapping hardware register
>> set for this remapping unit, is introduced in the DMA-remapping hardware
>> unit definition (DRHD) structure with the VT-d Spec 4.0.
>> With the information, SW doesn't need to 'guess' the size of the
>> register set anymore.
>>
>> Update the struct acpi_dmar_hardware_unit to reflect the field.
>>
>> Store the size of the register set in struct dmar_drhd_unit for each
>> dmar device.
>>
>> The 'size' information is ResvZ for the old BIOS and platforms. Fall
>> back to the old guessing method. There is nothing changed.
>>
>> Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
>> ---
>>   drivers/iommu/intel/dmar.c | 25 ++++++++++++++++++-------
>>   include/acpi/actbl1.h      |  2 +-
>>   include/linux/dmar.h       |  1 +
>>   3 files changed, 20 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
>> index b00a0ceb2d13..6a411d964474 100644
>> --- a/drivers/iommu/intel/dmar.c
>> +++ b/drivers/iommu/intel/dmar.c
>> @@ -399,6 +399,13 @@ dmar_find_dmaru(struct acpi_dmar_hardware_unit
>> *drhd)
>>       return NULL;
>>   }
>>   +/* The size of the register set is 2 ^ N 4 KB pages. */
>> +static unsigned long
>> +dmar_get_drhd_reg_size(u8 npages)
> 
> No need to divide it into two lines. Or put this line of code directly
> where it is called?
> 
>> +{
>> +    return 1UL << (npages + 12);
>> +}
>> +
>>   /*
>>    * dmar_parse_one_drhd - parses exactly one DMA remapping hardware
>> definition
>>    * structure which uniquely represent one DMA remapping hardware unit
>> @@ -427,6 +434,7 @@ static int dmar_parse_one_drhd(struct
>> acpi_dmar_header *header, void *arg)
>>       memcpy(dmaru->hdr, header, header->length);
>>       dmaru->reg_base_addr = drhd->address;
>>       dmaru->segment = drhd->segment;
>> +    dmaru->reg_size = dmar_get_drhd_reg_size(drhd->size);
>>       dmaru->include_all = drhd->flags & 0x1; /* BIT0: INCLUDE_ALL */
>>       dmaru->devices = dmar_alloc_dev_scope((void *)(drhd + 1),
>>                             ((void *)drhd) + drhd->header.length,
>> @@ -880,6 +888,7 @@ dmar_validate_one_drhd(struct acpi_dmar_header
>> *entry, void *arg)
>>       struct acpi_dmar_hardware_unit *drhd;
>>       void __iomem *addr;
>>       u64 cap, ecap;
>> +    unsigned long size;
>>         drhd = (void *)entry;
>>       if (!drhd->address) {
>> @@ -887,10 +896,11 @@ dmar_validate_one_drhd(struct acpi_dmar_header
>> *entry, void *arg)
>>           return -EINVAL;
>>       }
>>   +    size = dmar_get_drhd_reg_size(drhd->size);
>>       if (arg)
>> -        addr = ioremap(drhd->address, VTD_PAGE_SIZE);
>> +        addr = ioremap(drhd->address, size);
>>       else
>> -        addr = early_ioremap(drhd->address, VTD_PAGE_SIZE);
>> +        addr = early_ioremap(drhd->address, size);
>>       if (!addr) {
>>           pr_warn("Can't validate DRHD address: %llx\n", drhd->address);
>>           return -EINVAL;
>> @@ -902,7 +912,7 @@ dmar_validate_one_drhd(struct acpi_dmar_header
>> *entry, void *arg)
>>       if (arg)
>>           iounmap(addr);
>>       else
>> -        early_iounmap(addr, VTD_PAGE_SIZE);
>> +        early_iounmap(addr, size);
>>         if (cap == (uint64_t)-1 && ecap == (uint64_t)-1) {
>>           warn_invalid_dmar(drhd->address, " returns all ones");
> 
> The cap and ecap registers are always in the first page. Just map one
> 4K page is enough. There is no need to change it?

Right, one page should be enough for cap and ecap.

The perf cap will be checked in the alloc_iommu_pmu() of patch 2. If it
fails, it should not impact the existing features. No need to change
here. I will update it in V2.

After the change, there will be only one place which invokes
dmar_get_drhd_reg_size(). I will move it to the place as well.

> 
>> @@ -956,17 +966,18 @@ static void unmap_iommu(struct intel_iommu *iommu)
>>   /**
>>    * map_iommu: map the iommu's registers
>>    * @iommu: the iommu to map
>> - * @phys_addr: the physical address of the base resgister
>> + * @drhd: DMA remapping hardware definition structure
>>    *
>>    * Memory map the iommu's registers.  Start w/ a single page, and
>>    * possibly expand if that turns out to be insufficent.
>>    */
>> -static int map_iommu(struct intel_iommu *iommu, u64 phys_addr)
>> +static int map_iommu(struct intel_iommu *iommu, struct dmar_drhd_unit
>> *drhd)
>>   {
>> +    u64 phys_addr = drhd->reg_base_addr;
>>       int map_size, err=0;
>>         iommu->reg_phys = phys_addr;
>> -    iommu->reg_size = VTD_PAGE_SIZE;
>> +    iommu->reg_size = drhd->reg_size;
>>         if (!request_mem_region(iommu->reg_phys, iommu->reg_size,
>> iommu->name)) {
>>           pr_err("Can't reserve memory\n");
>> @@ -1050,7 +1061,7 @@ static int alloc_iommu(struct dmar_drhd_unit *drhd)
>>       }
>>       sprintf(iommu->name, "dmar%d", iommu->seq_id);
>>   -    err = map_iommu(iommu, drhd->reg_base_addr);
>> +    err = map_iommu(iommu, drhd);
>>       if (err) {
>>           pr_err("Failed to map %s\n", iommu->name);
>>           goto error_free_seq_id;
>> diff --git a/include/acpi/actbl1.h b/include/acpi/actbl1.h
>> index 4175dce3967c..bdded0ac46eb 100644
>> --- a/include/acpi/actbl1.h
>> +++ b/include/acpi/actbl1.h
>> @@ -802,7 +802,7 @@ struct acpi_dmar_pci_path {
>>   struct acpi_dmar_hardware_unit {
>>       struct acpi_dmar_header header;
>>       u8 flags;
>> -    u8 reserved;
>> +    u8 size;        /* Size of the register set */
>>       u16 segment;
>>       u64 address;        /* Register Base Address */
>>   };
>> diff --git a/include/linux/dmar.h b/include/linux/dmar.h
>> index d81a51978d01..51d498f0a02b 100644
>> --- a/include/linux/dmar.h
>> +++ b/include/linux/dmar.h
>> @@ -46,6 +46,7 @@ struct dmar_drhd_unit {
>>       u8    include_all:1;
>>       u8    gfx_dedicated:1;    /* graphic dedicated    */
>>       struct intel_iommu *iommu;
>> +    unsigned long reg_size;        /* size of register set */
> 
> Move it up and pair it with reg_base_addr.

Sure.

Thanks,
Kan
> 
>>   };
>>     struct dmar_pci_path {
> 
> -- 
> Best regards,
> baolu